[
  {
    "id": "claim-01",
    "statement": "Influenza A virus reassigns its own polymerase toward genome synthesis using a small RNA copied from its genome termini",
    "status": "lab-led",
    "research_areas": [
      "influenza-genome-regulation"
    ],
    "substantiated_by": [
      {
        "slug": "2010-perez-influenza-a-virus-generated-small-",
        "contributes": "identifies the species, establishes that it is made across subtypes and hosts, and shows segment-specific loss of genome synthesis when it is blocked"
      },
      {
        "slug": "2012-perez-a-small-rna-enhancer-of-viral-poly",
        "contributes": "establishes the template, the polymerase binding site and a non-priming mechanism in a reconstituted reaction, and carries the priority claim"
      }
    ],
    "url": "/discoveries/influenza-small-viral-rnas/",
    "narrative_markdown": "**Status** lab-led\n**Areas** influenza-genome-regulation\n\nOne heterotrimeric polymerase performs two incompatible reactions on the same eight templates. Messenger RNA synthesis requires the enzyme to stay bound in cis to the 5 prime template end, which is also what forces the stuttering that builds the poly(A) tail, while genome synthesis is primer independent and requires the enzyme to read through that same end. Perez 2010 states the paradox directly and records that the models then available did not reconcile it. The field had correlates for the transition, including stabilisation of the complementary RNA intermediate, nucleotide concentration and the soluble pools of nucleoprotein and polymerase, but no molecular event that reassigned the enzyme.\n\nDeep sequencing of the sub-40 nucleotide RNA fraction of infected lung epithelial cells found a discrete species of 22 to 27 nucleotides matching the 5 prime terminus of each of the eight genomic segments, distributed as a terminal hotspot rather than as breakdown product, produced by H1N1, H3N2 and H5N1 and across human, canine, murine and avian systems, and not induced by an unrelated virus or by type I interferon (Perez 2010). Locked nucleic acid inhibition directed at one segment's species depleted that segment's genomic RNA while sparing messenger and complementary RNA and the other seven segments. Perez 2012 then placed the species on the complementary RNA intermediate as template, showed it stays nuclear and is largely excluded from virions, mapped binding to the PB1 and PA heterodimer with the basic residue R566 of PA most important, and reproduced the effect in a cell-free reaction with purified trimer where synthetic small viral RNA promoted full-length synthesis even with its 3 prime hydroxyl blocked, which excludes priming, with the first 13 nucleotides sufficient. A recombinant virus unable to generate the species from the neuraminidase segment lost genome synthesis for that segment alone while retaining neuraminidase messenger RNA. Perez 2012 states in its own discussion that this is the first example of a small RNA controlling RNA-dependent RNA polymerase activity, and that priority claim belongs to the paper rather than to this document.\n\nWhat is now known is that the influenza polymerase carries a ligand, made as a product of copying its own genome, whose presence shifts its output toward full-length genome synthesis for the segment it came from. What is not known is how the species is made, whether it causes the transition rather than accompanying it, or whether each segment truly carries its own loaded replicase and whether that is how the eight segments are held in balance. No polymerase occupancy measurement and no structure of the complex exists in either paper, and Perez 2012 cautions that the promiscuity of a short synthetic mimetic in vitro may not reflect what the virus uses in a cell. The line did not continue as a dedicated program. Its clearest later appearance is as a distinct band alongside mini-viral RNA in Nilsson-Payant 2021.\n\n**Substantiated by**\n- 2010-perez-influenza-a-virus-generated-small-, identifies the species, establishes that it is made across subtypes and hosts, and shows segment-specific loss of genome synthesis when it is blocked\n- 2012-perez-a-small-rna-enhancer-of-viral-poly, establishes the template, the polymerase binding site and a non-priming mechanism in a reconstituted reaction, and carries the priority claim",
    "supporting_publications": [
      {
        "id": "2010-perez-influenza-a-virus-generated-small-",
        "url": "https://tenoeverlab.us/publications/2010-perez-influenza-a-virus-generated-small-/",
        "evidence": "identifies the species, establishes that it is made across subtypes and hosts, and shows segment-specific loss of genome synthesis when it is blocked"
      },
      {
        "id": "2012-perez-a-small-rna-enhancer-of-viral-poly",
        "url": "https://tenoeverlab.us/publications/2012-perez-a-small-rna-enhancer-of-viral-poly/",
        "evidence": "establishes the template, the polymerase binding site and a non-priming mechanism in a reconstituted reaction, and carries the priority claim"
      }
    ]
  },
  {
    "id": "claim-02",
    "statement": "An inefficient splice site paces influenza gene expression, and the same processing step is a vulnerability across the orthomyxovirus family",
    "status": "lab-led",
    "research_areas": [
      "influenza-genome-regulation"
    ],
    "substantiated_by": [
      {
        "slug": "2013-chua-influenza-a-virus-utilizes-subopti",
        "contributes": "establishes the splice site as a rate-setting timer and that most NS1 is dispensable for antagonism"
      },
      {
        "slug": "2023-oishi-archaeal-kink-turn-binding-protein",
        "contributes": "separates orthomyxovirus splicing from host splicing with a heterologous protein and extends the vulnerability across three genera"
      }
    ],
    "url": "/discoveries/influenza-splicing-timer/",
    "narrative_markdown": "**Status** lab-led\n**Areas** influenza-genome-regulation\n\nInfluenza A virus drives its eight segments from comparable promoters and has no transcription factors, so it cannot delay a protein by transcribing its segment later. Segment 8 is bicistronic, with the unspliced transcript encoding the interferon antagonist NS1 and a 5 prime splice site used only ten to fifteen percent of the time yielding the nuclear export protein required for export of nucleoprotein-associated genomes. Whether that inefficiency was functional or incidental was open, and the mechanism executing influenza splicing was unidentified, having never been reconstituted in vitro.\n\nChua 2013 moved each product in both directions. Silencing NS1 by more than ninety percent, using perfect microRNA target sites in the intergenic region of a modified NS vector, left titres and interferon-regulated gene induction close to control in lung epithelial cells, primary lung fibroblasts, bone marrow-derived macrophages and mice, in both interferon-competent and signalling-deficient animals, whereas a virus deleted for NS1 was heavily impaired. Lowering the export protein by a 2A recoding arrangement or by small interfering RNA cost titre, and raising it by an extra gene copy or by optimising the splice site cost about two logs in culture and nearly abolished replication in mice, with nucleoprotein reaching the cytoplasm as early as five hours in the splice-optimised virus. Two conclusions follow. Most NS1 is dispensable for antagonism in the settings tested, and the abundance of the NS1 transcript is load-bearing for the timing of its own minor spliced product rather than for antagonism.\n\nA decade later the archaeal kink-turn binding protein L7Ae was found to eliminate the spliced M2 and NS2 products while the unspliced M1 and NS1 accumulate, with no measurable effect on host splicing, on the host transcriptome and proteome, or on an intron-containing reporter (Oishi 2023). The effect required nuclear L7Ae, occurred without infection or viral polymerase, and disappeared against the splicing-independent 2A virus built in the Chua work, which is the decisive genetic test that the target is splicing. Sensitivity mapped to roughly twenty nucleotides of intron upstream of the 3 prime splice acceptor plus about nine nucleotides of coding sequence in both segment 7 and segment 8. The protein cost influenza A virus two to three logs and influenza B virus one to two logs and blocked splice product formation in infectious salmon anemia virus, while leaving vesicular stomatitis virus untouched. Twenty passages under selection produced no true escape, only a segment 8 variant that raises splicing efficiency at a severe fitness cost and is outcompeted by wild type within two passages once the inhibitor is removed.\n\nRead together the two papers make splice site suboptimality the mechanism by which the virus schedules its cycle and make that arrangement a family-level property, which is synthesis across the pair rather than a claim in either. What is not established is the structure L7Ae engages, since no canonical kink turn was found, crosslinking produced no footprint, and the mapping data are equally consistent with an indirect effect. The step at which mistimed export becomes lethal is not identified, and no experiment restores correct timing to rescue the titre defect. Readers should note the declared conflict in Oishi 2023, since tenOever is a co-founder of Archean Biologics and an author on a patent covering commercialisation of L7Ae.\n\n**Substantiated by**\n- 2013-chua-influenza-a-virus-utilizes-subopti, establishes the splice site as a rate-setting timer and that most NS1 is dispensable for antagonism\n- 2023-oishi-archaeal-kink-turn-binding-protein, separates orthomyxovirus splicing from host splicing with a heterologous protein and extends the vulnerability across three genera",
    "supporting_publications": [
      {
        "id": "2013-chua-influenza-a-virus-utilizes-subopti",
        "url": "https://tenoeverlab.us/publications/2013-chua-influenza-a-virus-utilizes-subopti/",
        "evidence": "establishes the splice site as a rate-setting timer and that most NS1 is dispensable for antagonism"
      },
      {
        "id": "2023-oishi-archaeal-kink-turn-binding-protein",
        "url": "https://tenoeverlab.us/publications/2023-oishi-archaeal-kink-turn-binding-protein/",
        "evidence": "separates orthomyxovirus splicing from host splicing with a heterologous protein and extends the vulnerability across three genera"
      }
    ]
  },
  {
    "id": "claim-03",
    "statement": "Nucleoprotein availability couples influenza replication competence to immune invisibility, so less replication can yield more interferon",
    "status": "lab-led",
    "research_areas": [
      "influenza-genome-regulation",
      "innate-immune-signaling"
    ],
    "substantiated_by": [
      {
        "slug": "2021-nilsson-payant-reduced-nucleoprotein-availability",
        "contributes": "separates protein supply from genome supply during infection and identifies the short products that RIG-I detects when nucleoprotein is scarce"
      }
    ],
    "url": "/discoveries/nucleoprotein-and-immune-sensing/",
    "narrative_markdown": "**Status** lab-led\n**Areas** influenza-genome-regulation, innate-immune-signaling\n\nNucleoprotein acts as an elongation factor, dispensable on templates up to about 76 nucleotides and supporting only diminished synthesis to about 125, which had been read as a way of prioritising viral protein synthesis before genome replication. It also shields viral RNA from host nucleases. Whether the amount of nucleoprotein governs host detection independently of its role in supporting replication had not been tested, because infection does not allow protein supply and genome supply to be separated.\n\nNilsson-Payant 2021 separated them by placing microRNA target sites downstream of the nucleoprotein open reading frame in recombinant influenza A and Sendai viruses, so nucleoprotein messenger RNA is degraded while the genomic RNA the polymerase copies is untouched, with matched nonfunctional-target viruses as controls. Silencing abolished detectable viral protein and full-length replication and yet strongly raised interferon-stimulated gene induction relative to the viral material present. Sequencing showed reduced coverage with enrichment at segment termini and increased noncanonical junction reads, and Northern blotting against the conserved 5 prime promoter showed mini-viral RNA accumulating from three hours and tracking with interferon beta induction. Titrating nucleoprotein against fixed polymerase in a reconstituted complex containing no NS1 reproduced the inverse relationship between full-length product and mini-viral RNA, and reporter cells placed the response through RIG-I and MAVS rather than MDA5. The same pairing of lost replication with IFIT1 induction held across seven negative-sense viruses in six families.\n\nThe claim this establishes is that a single viral protein sets a point where replication competence and immune invisibility cannot be traded independently, and that a perturbation lowering it buys reduced replication at the cost of a stronger response. A practical corollary is that the choice of drug target decides whether an antiviral also engages host defence, since nucleozin induced IFIT1 where the polymerase inhibitor baloxavir marboxil did not. The authors offer bystander priming as an extrapolation from two compounds in cell culture, and it should be read that way.\n\nBoundaries are specific. The relative contribution of mini-viral RNA against longer defective genomes is left unresolved by the authors, and junction-read counting substantially undercounts defective genomes. Knockdown of the SARS-CoV-2 nucleocapsid transcript reduced replication without inducing interferon, a contrast the paper does not resolve. All of the work is in cell lines, with no animal arm, so what nucleoprotein scarcity does in tissue is untested. The related finding that the host factor ANP32A is required at both steps of genome replication and acts on the actively synthesising rather than the encapsidating polymerase comes from Nilsson-Payant 2022, a collaborative study led by the te Velthuis laboratory at Princeton with the first author based in this laboratory, and it is that laboratory's result rather than this program's.\n\n**Substantiated by**\n- 2021-nilsson-payant-reduced-nucleoprotein-availability, separates protein supply from genome supply during infection and identifies the short products that RIG-I detects when nucleoprotein is scarce",
    "supporting_publications": [
      {
        "id": "2021-nilsson-payant-reduced-nucleoprotein-availability",
        "url": "https://tenoeverlab.us/publications/2021-nilsson-payant-reduced-nucleoprotein-availability/",
        "evidence": "separates protein supply from genome supply during infection and identifies the short products that RIG-I detects when nucleoprotein is scarce"
      }
    ]
  },
  {
    "id": "claim-04",
    "statement": "Much of the antiviral transcriptome can be induced without interferon, and which genes come on is decided by competition for shared transcription factor subunits",
    "status": "lab-led for Schmid 2010 and Schmid 2014, co-led with the Maniatis laboratory for Ng 2011, and training period for tenOever 2007, which was carried out with the Maniatis and García-Sastre laboratories and is not the independent program's work",
    "research_areas": [
      "innate-immune-signaling"
    ],
    "substantiated_by": [
      {
        "slug": "2007-tenoever-multiple-functions-of-the-ikk-rela",
        "contributes": "training-period work dividing interferon-stimulated response elements into kinase-dependent and kinase-independent classes and naming STAT1 Ser708"
      },
      {
        "slug": "2011-ng-i-b-kinase-ikk-regulates-the-balan",
        "contributes": "explains that phosphosite as a block on STAT1 homodimerisation that reallocates a shared subunit between two complexes"
      },
      {
        "slug": "2010-schmid-transcription-factor-redundancy-en",
        "contributes": "shows that much of the antiviral transcriptome is inducible without interferon and gives sequence criteria sorting promoters by the factor that reads them"
      },
      {
        "slug": "2014-schmid-mitogen-activated-protein-kinase-m",
        "contributes": "identifies a feedback kinase that changes which IRF dimer forms and therefore which promoters the response reaches"
      }
    ],
    "url": "/discoveries/interferon-transcriptional-selectivity/",
    "narrative_markdown": "**Status** lab-led for Schmid 2010 and Schmid 2014, co-led with the Maniatis laboratory for Ng 2011, and training period for tenOever 2007, which was carried out with the Maniatis and García-Sastre laboratories and is not the independent program's work\n**Areas** innate-immune-signaling\n\nThe interferon response had been described as a switch in which detection yields interferon, interferon signals, and a few hundred interferon-stimulated genes come on. That account cannot explain why the induced set differs between infections, cell types and host genotypes, and it treats a gene annotated as interferon-stimulated as though its induction required interferon. The training-period observation that framed the problem is that mice lacking IKKepsilon made normal interferon beta yet failed to induce roughly a third of interferon-stimulated genes, that the defect persisted when interferon was supplied from outside the cell, and that the substrate separating responsive from unresponsive promoters was STAT1 Ser708 (tenOever 2007).\n\nTwo mechanisms of allocation were then established. Ng 2011 placed Ser708 in the homodimer interface of the published tyrosine-phosphorylated STAT1 structure and showed that phosphorylation there blocks the activated homodimer while leaving the STAT1 and STAT2 interaction intact, so a limiting STAT1 pool is driven into ISGF3 and away from GAF. Loss of IKKepsilon lowered ISGF3 assembly and element binding while raising GAF assembly, and adenoviral IKKepsilon produced the mirror-image shift. Schmid 2014 found the same logic among the interferon regulatory factors, where the IRF7-selective kinase MAP3K8 drives phosphorylation in the proline-rich hinge of IRF3 and redirects it from homodimers into IRF3 and IRF7 heterodimers, with fibroblasts lacking MAP3K8 supporting more vesicular stomatitis virus and failing to induce roughly seventy genes.\n\nThe DNA side supplied the other half. Mice lacking both the type I and type III interferon receptors still induced a large block of interferon-stimulated genes after infection with an NS1-deficient influenza A virus, so those genes do not require interferon signalling, and systematic mutagenesis of the ISG15 element separated positions conferring IRF7 specificity, ISGF3 specificity or both, with ISGF3 requiring contacts beyond the consensus core and IRF7 tolerating more variation (Schmid 2010). Activating IRF7 in interferon-unresponsive cells reproduced about eighty percent of the set induced in infected knockout lung, and individual promoters sorted as predicted, with MxA restricted to ISGF3 and CXCL10 to IRF7.\n\nWhat is now known is that the interferon-stimulated gene set is a structured and divisible output, that a large part of it is inducible with no interferon signalling at all, and that composition is set by which complex assembles and which element it can read. The reading that one design principle appears twice, a kinase acting at or near a dimer interface to allocate a shared subunit, is synthesis across Ng 2011 and Schmid 2014 and is asserted by neither. The structural chemistry is unresolved, since Ng 2011 states that the consequences of Ser708 phosphorylation within ISGF3 are unknown and Schmid 2014 does not establish MAP3K8 as a direct kinase for IRF3 or identify the modified hinge residues. The consensus sequences in Schmid 2010 are generalisations from derivatives of one element, and the thread did not continue as a mechanistic program after 2014.\n\n**Substantiated by**\n- 2007-tenoever-multiple-functions-of-the-ikk-rela, training-period work dividing interferon-stimulated response elements into kinase-dependent and kinase-independent classes and naming STAT1 Ser708\n- 2011-ng-i-b-kinase-ikk-regulates-the-balan, explains that phosphosite as a block on STAT1 homodimerisation that reallocates a shared subunit between two complexes\n- 2010-schmid-transcription-factor-redundancy-en, shows that much of the antiviral transcriptome is inducible without interferon and gives sequence criteria sorting promoters by the factor that reads them\n- 2014-schmid-mitogen-activated-protein-kinase-m, identifies a feedback kinase that changes which IRF dimer forms and therefore which promoters the response reaches",
    "supporting_publications": [
      {
        "id": "2007-tenoever-multiple-functions-of-the-ikk-rela",
        "url": "https://tenoeverlab.us/publications/2007-tenoever-multiple-functions-of-the-ikk-rela/",
        "evidence": "training-period work dividing interferon-stimulated response elements into kinase-dependent and kinase-independent classes and naming STAT1 Ser708"
      },
      {
        "id": "2011-ng-i-b-kinase-ikk-regulates-the-balan",
        "url": "https://tenoeverlab.us/publications/2011-ng-i-b-kinase-ikk-regulates-the-balan/",
        "evidence": "explains that phosphosite as a block on STAT1 homodimerisation that reallocates a shared subunit between two complexes"
      },
      {
        "id": "2010-schmid-transcription-factor-redundancy-en",
        "url": "https://tenoeverlab.us/publications/2010-schmid-transcription-factor-redundancy-en/",
        "evidence": "shows that much of the antiviral transcriptome is inducible without interferon and gives sequence criteria sorting promoters by the factor that reads them"
      },
      {
        "id": "2014-schmid-mitogen-activated-protein-kinase-m",
        "url": "https://tenoeverlab.us/publications/2014-schmid-mitogen-activated-protein-kinase-m/",
        "evidence": "identifies a feedback kinase that changes which IRF dimer forms and therefore which promoters the response reaches"
      }
    ]
  },
  {
    "id": "claim-05",
    "statement": "Interferon and interferon-stimulated gene loci are held off during homeostasis by a DNA-binding repressor complex that virus entry destroys within minutes",
    "status": "collaborative, led by the Manicassamy laboratory, with Han 2018 published from the University of Chicago with Balaji Manicassamy as corresponding author and Manivasagam 2025 with Priya Issuree and Balaji Manicassamy as corresponding authors. The discovery belongs to those groups. The tenOever contribution is recorded as one author in the Han 2018 list and as investigation in Manivasagam 2025",
    "research_areas": [
      "innate-immune-signaling"
    ],
    "substantiated_by": [
      {
        "slug": "2018-han-genome-wide-crispr-cas9-screen-ide",
        "contributes": "identifies capicua as a repressor whose loss raises the antiviral set point across four virus families"
      },
      {
        "slug": "2025-manivasagam-transcriptional-repressor-capicua-",
        "contributes": "places the repressor complex at motif-dependent loci during homeostasis and identifies the receptor-to-proteasome route that removes it"
      }
    ],
    "url": "/discoveries/homeostatic-repression/",
    "narrative_markdown": "**Status** collaborative, led by the Manicassamy laboratory, with Han 2018 published from the University of Chicago with Balaji Manicassamy as corresponding author and Manivasagam 2025 with Priya Issuree and Balaji Manicassamy as corresponding authors. The discovery belongs to those groups. The tenOever contribution is recorded as one author in the Han 2018 list and as investigation in Manivasagam 2025\n**Areas** innate-immune-signaling\n\nSafeguards against spontaneous antiviral activation had been described almost entirely upstream of transcription, acting on sensing and signalling through suppression of receptor components, post-translational modification, or editing of endogenous double-stranded RNA by ADAR1 so that MDA5 is not engaged. Interferon and interferon-stimulated gene promoters themselves were treated as sitting in a default off state awaiting an activated interferon regulatory factor or ISGF3, with FOXO3 repression of the Irf7 promoter as the noted exception. That leaves unexplained why basal expression is as low as it is in cells continuously generating host-derived double-stranded RNA.\n\nHan 2018 recovered capicua, a conserved HMG-box repressor previously studied in development, cancer and neurodegeneration, from a survival-based genome-wide CRISPR screen whose dominant signal was sialic acid biosynthesis and transport. Loss of capicua restricted influenza A virus and also vesicular stomatitis, Zika and encephalomyocarditis viruses, raised antiviral gene expression under mock and infected conditions, and capicua protein fell between forty and sixty minutes after infection. Manivasagam 2025 converted that into a mechanism. Knockouts of capicua and of its obligate partner ATXN1L raised interferon and interferon-stimulated gene transcripts and restricted influenza A virus, reproduced by knockdown in primary human airway basal cells and by conditional knockout in mice. The basal signal required MAVS, which the authors read as tonic RIG-I-like receptor engagement by host-derived ligands. Chromatin accessibility rose at matching loci, reporter work with native and mutated binding-site motifs and a synthetic capicua carrying VP16 repeats established motif dependence in both directions, and the complex is degraded by the proteasome within forty minutes of synchronised infection, before genome replication, through EGFR-MAPK signalling, reproduced by recombinant hemagglutinin or by EGF alone and blocked by MEK or ERK inhibition. Capicua knockout mice lost less weight and carried 5 to 50-fold lower lung viral burden.\n\nThe consequence for the rest of this corpus is that a promoter's behaviour reflects both which activators are available and whether a repressor has been removed, which read against Schmid 2010 completes the picture from the repressive side. That combined reading is synthesis and is drawn in neither paper. Direct occupancy of endogenous loci was not measured in either study, the motif is the Drosophila consensus and is carried by 93 percent of the differentially accessible genes, the functional motif evidence comes from transfected reporters rather than native chromatin, and no ubiquitin ligase or ERK substrate site is identified. The line runs from an unexplained screen hit in 2018 to a characterised repressor in 2025 with a seven-year gap and no intervening publication in this corpus.\n\n**Substantiated by**\n- 2018-han-genome-wide-crispr-cas9-screen-ide, identifies capicua as a repressor whose loss raises the antiviral set point across four virus families\n- 2025-manivasagam-transcriptional-repressor-capicua-, places the repressor complex at motif-dependent loci during homeostasis and identifies the receptor-to-proteasome route that removes it",
    "supporting_publications": [
      {
        "id": "2018-han-genome-wide-crispr-cas9-screen-ide",
        "url": "https://tenoeverlab.us/publications/2018-han-genome-wide-crispr-cas9-screen-ide/",
        "evidence": "identifies capicua as a repressor whose loss raises the antiviral set point across four virus families"
      },
      {
        "id": "2025-manivasagam-transcriptional-repressor-capicua-",
        "url": "https://tenoeverlab.us/publications/2025-manivasagam-transcriptional-repressor-capicua-/",
        "evidence": "places the repressor complex at motif-dependent loci during homeostasis and identifies the receptor-to-proteasome route that removes it"
      }
    ]
  },
  {
    "id": "claim-06",
    "statement": "Engaging the interferon program carries costs that constrain where it can be run, and detection has to be buffered as well as triggered",
    "status": "lab-led for Eggenberger 2019 and for the tenOever 2016 Perspective, which is single-authored and synthesises work largely belonging to other groups. Paget 2023 is collaborative and was led by the Hur laboratory at Harvard with Sun Hur as sole corresponding author, and the tenOever contribution there is recorded as provision of reagents, so that discovery is not this program's",
    "research_areas": [
      "innate-immune-signaling",
      "small-rna-antiviral-defense"
    ],
    "substantiated_by": [
      {
        "slug": "2019-eggenberger-type-i-interferon-response-impairs",
        "contributes": "forces the program into cells that cannot otherwise run it and measures lasting transcriptional change and compromised germ layer potential"
      },
      {
        "slug": "2023-paget-stress-granules-are-shock-absorber",
        "contributes": "led by the Hur laboratory, reverses the reading of stress granules and shows that unbuffered double-stranded RNA sensing kills through MAVS"
      },
      {
        "slug": "2016-tenoever-the-evolution-of-antiviral-defense",
        "contributes": "single-author Perspective supplying the framework in which two antiviral systems can be mutually incompatible"
      }
    ],
    "url": "/discoveries/costs-of-antiviral-defense/",
    "narrative_markdown": "**Status** lab-led for Eggenberger 2019 and for the tenOever 2016 Perspective, which is single-authored and synthesises work largely belonging to other groups. Paget 2023 is collaborative and was led by the Hur laboratory at Harvard with Sun Hur as sole corresponding author, and the tenOever contribution there is recorded as provision of reagents, so that discovery is not this program's\n**Areas** innate-immune-signaling, small-rna-antiviral-defense\n\nPluripotent cells were the standing exception to the claim that the type I interferon system is available to any vertebrate cell, and the explanations offered had all addressed how the response is absent rather than why the system is unused. Reframing the question as compatibility changes what must be measured, from what blocks the response to what engaging it would cost.\n\nEggenberger 2019 built an internal comparison by reprogramming human primary fibroblasts to induced pluripotent cells and redifferentiating them, so that two states of one genetic background could be set side by side. Only the pluripotent state failed to respond to 5 prime triphosphate RNA, to interferon beta or to influenza A virus lacking NS1, and redifferentiation restored responsiveness, which excludes clonal selection. Mouse embryonic stem cells behaved the same way. Co-expression of OCT4, SOX2 or KLF4 with a constitutively active IRF7 in competent cells repressed IFIT1 and ISG15 induction, with KLF4 most potent. The consequence side is the substantive result. A forty-eight hour pulse of a truncated IRF7 that bypasses kinase activation left roughly 2,000 genes differentially expressed five days later, after IRF7 and its direct targets had returned to baseline, with NANOG and IDO1 dysregulated and subsequent differentiation compromised for ectoderm and endoderm and distorted within mesoderm.\n\nThe restraint side of the same argument comes from work led elsewhere. Paget 2023 tested the prevailing reading that stress granules are signalling platforms for RIG-I-like receptors and found the opposite, using three genetically distinct routes to granule deficiency. All three showed stronger signalling to a defined double-stranded RNA at the level of transcriptome, cytokine messenger RNA and protein, IRF3 activation and cell-free MAVS signalling potential, and granule-deficient cells underwent caspase-dependent apoptosis largely rescued by deleting MAVS but not IRF3. Restoring granules in PKR-deficient cells suppressed signalling, and the protection extended to endogenous double-stranded RNA accumulating after ADAR1 knockdown.\n\nWhat is now known is that the antiviral transcriptional program is not cost-free and is not compatible with every cell state, and that unbuffered detection of double-stranded RNA is lethal through MAVS independently of interferon. What is not known is whether the program is incompatible with pluripotency in a developing organism, since all of Eggenberger 2019 is in vitro with an artificial driving construct at one dose and duration, and how granules suppress signalling, which the authors of Paget 2023 state is unresolved. The broader proposal that chordates lost RNA silencing through incompatibility with interferon rather than through redundancy is labelled an attractive hypothesis by tenOever 2016, whose supporting evidence is correlative and largely other laboratories' work, and no later publication in this corpus returns to pluripotency.\n\n**Substantiated by**\n- 2019-eggenberger-type-i-interferon-response-impairs, forces the program into cells that cannot otherwise run it and measures lasting transcriptional change and compromised germ layer potential\n- 2023-paget-stress-granules-are-shock-absorber, led by the Hur laboratory, reverses the reading of stress granules and shows that unbuffered double-stranded RNA sensing kills through MAVS\n- 2016-tenoever-the-evolution-of-antiviral-defense, single-author Perspective supplying the framework in which two antiviral systems can be mutually incompatible",
    "supporting_publications": [
      {
        "id": "2019-eggenberger-type-i-interferon-response-impairs",
        "url": "https://tenoeverlab.us/publications/2019-eggenberger-type-i-interferon-response-impairs/",
        "evidence": "forces the program into cells that cannot otherwise run it and measures lasting transcriptional change and compromised germ layer potential"
      },
      {
        "id": "2023-paget-stress-granules-are-shock-absorber",
        "url": "https://tenoeverlab.us/publications/2023-paget-stress-granules-are-shock-absorber/",
        "evidence": "led by the Hur laboratory, reverses the reading of stress granules and shows that unbuffered double-stranded RNA sensing kills through MAVS"
      },
      {
        "id": "2016-tenoever-the-evolution-of-antiviral-defense",
        "url": "https://tenoeverlab.us/publications/2016-tenoever-the-evolution-of-antiviral-defense/",
        "evidence": "single-author Perspective supplying the framework in which two antiviral systems can be mutually incompatible"
      }
    ]
  },
  {
    "id": "claim-07",
    "statement": "Drosha acts in the cytoplasm during infection and restricts positive-strand RNA viruses by binding structured RNA rather than by producing small interfering RNAs",
    "status": "lab-led",
    "research_areas": [
      "small-rna-antiviral-defense"
    ],
    "substantiated_by": [
      {
        "slug": "2010-shapiro-noncanonical-cytoplasmic-processin",
        "contributes": "establishes that a cytoplasmic virus can yield mature microRNA and reports the processing requirement as microprocessor independent"
      },
      {
        "slug": "2012-shapiro-evidence-for-a-cytoplasmic-micropr",
        "contributes": "corrects that reading by conditional deletion and shows Drosha relocalising to the cytoplasm in response to infection"
      },
      {
        "slug": "2014-shapiro-drosha-as-an-interferon-independen",
        "contributes": "shows Drosha but not Dicer restricting two RNA viruses without any small interfering RNA signature, independently of three sensing lesions"
      },
      {
        "slug": "2017-aguado-rnase-iii-nucleases-from-diverse-k",
        "contributes": "shows that RNA binding without catalysis suffices, identifies unbranched hairpins as the recognised structure, and reproduces the activity with RNase III proteins from three domains of life"
      }
    ],
    "url": "/discoveries/drosha-antiviral-restriction/",
    "narrative_markdown": "**Status** lab-led\n**Areas** small-rna-antiviral-defense\n\nThe dispute over mammalian antiviral silencing had been conducted in terms of products, over whether virus-derived small interfering RNAs of the right size and Dicer dependence could be found in infected cells. That framing assumes the only antiviral use of the silencing machinery is to make small RNAs. Two observations from the laboratory's own engineering work pointed elsewhere. Cytoplasmic processing of a primary microRNA transcript carried by an alphavirus was initially reported as microprocessor independent in Shapiro 2010, and Shapiro 2012 in RNA, using conditional deletion rather than inference, found Drosha absolutely required and Dicer needed only at the second cleavage, revising that earlier reading. The same study found endogenous Drosha redistributing from nucleus to cytoplasm after infection with parental as well as microRNA-expressing virus, so relocalisation responds to infection rather than to the presence of a substrate.\n\nShapiro 2014 separated the two RNase III enzymes genetically in primary fibroblasts. Loss of Drosha raised Sindbis and vesicular stomatitis virus titres and capsid protein while loss of Dicer had no significant effect. Infection with positive-sense, negative-sense and segmented nuclear RNA viruses, and transfection of double-stranded RNA alone, drove Drosha into the cytoplasm within six hours by CRM1-dependent export, without new protein synthesis and in cells lacking RIG-I, TBK1 or the type I interferon receptor, which is the basis for calling the activity interferon independent. A variant with serines 300 and 302 replaced by alanine was constitutively cytoplasmic and restricted Sindbis virus by more than two logs against about one log for wild type. The decisive negative result sits in the same paper, since more than 675,000 small RNA reads across the Sindbis genome showed no enrichment of the 21 nucleotide species, and loss of Drosha raised total viral small RNA reads without changing their profile.\n\nAguado 2017 established what the enzyme recognises. In cells lacking both Drosha and Dicer, and therefore any mature microRNA, Sindbis, Ross River and Langat viruses replicated better while influenza A and Sendai viruses did not, so enhancement tracked with positive genome polarity, reproduced in primary conditional Drosha mouse lung fibroblasts. Among six variants unable to process primary microRNAs, an RNA-binding mutant that is catalytically inactive and does not associate with DGCR8 still suppressed the virus, so the activity requires RNA binding and requires neither catalysis, nor DGCR8, nor microRNA processing. SELEX enriched RNAs with no conserved sequence that fold into unbranched hairpins, and the same protein bound a hairpin in the first 200 nucleotides of the Sindbis genome. Replicon work localised the defect to RNA synthesis, and a reconstituted minus-strand replicase assay showed polymerase output reduced by nearly half in fractions containing Drosha. RNase III proteins from bacteria, archaea, yeast and the urochordate Ciona intestinalis conferred the same activity against positive-strand viruses, which converts a Drosha observation into a statement about a protein fold.\n\nThis is a position neither side of the 2013 antiviral silencing dispute occupied. A component of the silencing machinery does contribute to antiviral defence in mammalian somatic cells, and it does so without the small interfering RNA products the dispute was about. The clamp model the authors use for steric occlusion is their interpretation, with no structural or single-molecule evidence, and the study does not test why encapsidated negative-strand genomes escape. The activity that converts a cytoplasmic primary transcript into a precursor was never identified in this corpus, the phosphatase implied by the serine data was not found, and both papers are bounded to cultured cells with no mammalian animal infection.\n\n**Substantiated by**\n- 2010-shapiro-noncanonical-cytoplasmic-processin, establishes that a cytoplasmic virus can yield mature microRNA and reports the processing requirement as microprocessor independent\n- 2012-shapiro-evidence-for-a-cytoplasmic-micropr, corrects that reading by conditional deletion and shows Drosha relocalising to the cytoplasm in response to infection\n- 2014-shapiro-drosha-as-an-interferon-independen, shows Drosha but not Dicer restricting two RNA viruses without any small interfering RNA signature, independently of three sensing lesions\n- 2017-aguado-rnase-iii-nucleases-from-diverse-k, shows that RNA binding without catalysis suffices, identifies unbranched hairpins as the recognised structure, and reproduces the activity with RNase III proteins from three domains of life",
    "supporting_publications": [
      {
        "id": "2010-shapiro-noncanonical-cytoplasmic-processin",
        "url": "https://tenoeverlab.us/publications/2010-shapiro-noncanonical-cytoplasmic-processin/",
        "evidence": "establishes that a cytoplasmic virus can yield mature microRNA and reports the processing requirement as microprocessor independent"
      },
      {
        "id": "2012-shapiro-evidence-for-a-cytoplasmic-micropr",
        "url": "https://tenoeverlab.us/publications/2012-shapiro-evidence-for-a-cytoplasmic-micropr/",
        "evidence": "corrects that reading by conditional deletion and shows Drosha relocalising to the cytoplasm in response to infection"
      },
      {
        "id": "2014-shapiro-drosha-as-an-interferon-independen",
        "url": "https://tenoeverlab.us/publications/2014-shapiro-drosha-as-an-interferon-independen/",
        "evidence": "shows Drosha but not Dicer restricting two RNA viruses without any small interfering RNA signature, independently of three sensing lesions"
      },
      {
        "id": "2017-aguado-rnase-iii-nucleases-from-diverse-k",
        "url": "https://tenoeverlab.us/publications/2017-aguado-rnase-iii-nucleases-from-diverse-k/",
        "evidence": "shows that RNA binding without catalysis suffices, identifies unbranched hairpins as the recognised structure, and reproduces the activity with RNase III proteins from three domains of life"
      }
    ]
  },
  {
    "id": "claim-08",
    "statement": "Vertebrate somatic cells do not rely on small RNA silencing against viruses, and the reason is not that such a defence would fail in a mammalian cell",
    "status": "lab-led for Backes 2014, Benitez 2015 on engineered RNA interference, Aguado 2015 and the tenOever 2013 review, co-led with the Cherry laboratory for Backes 2012, and collaborative for Cullen 2013, a Minireview led by Bryan Cullen with Sara Cherry and tenOever",
    "research_areas": [
      "small-rna-antiviral-defense"
    ],
    "substantiated_by": [
      {
        "slug": "2012-backes-degradation-of-host-micrornas-by-p",
        "contributes": "identifies VP55 as sufficient to tail and destroy RISC-loaded microRNAs and supplies the reagent the rest of the argument depends on"
      },
      {
        "slug": "2014-backes-the-mammalian-response-to-virus-in",
        "contributes": "shows that destroying host microRNAs gives a virus no fitness benefit, including in animals lacking both interferon receptors"
      },
      {
        "slug": "2015-aguado-microrna-function-is-limited-to-cy",
        "contributes": "shows that removing microRNAs leaves the intrinsic antiviral program intact and derepresses chemokines and cytokines instead"
      },
      {
        "slug": "2015-benitez-engineered-mammalian-rnai-can-elic",
        "contributes": "shows that a reconstructed slicing defence protects mice with no contribution from type I interferon signalling"
      },
      {
        "slug": "2013-tenoever-rna-viruses-and-the-host-microrna-",
        "contributes": "argues from copy number, silencing capacity and kinetics that chordate microRNAs cannot be antiviral"
      },
      {
        "slug": "2013-cullen-is-rna-interference-a-physiologica",
        "contributes": "led by Bryan Cullen, sets the evidentiary criteria and states why the positive claims then available did not meet them"
      }
    ],
    "url": "/discoveries/reconstructing-antiviral-rnai/",
    "narrative_markdown": "**Status** lab-led for Backes 2014, Benitez 2015 on engineered RNA interference, Aguado 2015 and the tenOever 2013 review, co-led with the Cherry laboratory for Backes 2012, and collaborative for Cullen 2013, a Minireview led by Bryan Cullen with Sara Cherry and tenOever\n**Areas** small-rna-antiviral-defense\n\nPlants, nematodes and arthropods process viral double-stranded RNA into small interfering RNAs that guide cleavage of viral transcripts, and their viruses encode suppressors of the pathway. Vertebrates detect the same double-stranded RNA and answer it transcriptionally while retaining most of the silencing machinery. Whether they also retain a functioning antiviral arm was genuinely open, and the question was reopened in 2013 by reports from the Voinnet and Ding groups. Cullen 2013 accepts the mouse embryonic stem cell evidence, declines to settle the somatic case, and names the reason the positive claims are not decisive, which is that the viral proteins they rest on bind double-stranded RNA and also antagonise interferon, so the two explanations have not been separated.\n\nThe negative half of the answer was obtained as a fitness experiment rather than by removing host components. Backes 2014 armed vesicular stomatitis virus with vaccinia VP55, the poly(A) polymerase subunit that Backes 2012 had identified as tailing RISC-loaded small RNAs for host-supplied decay, and compared it with a virus carrying influenza NS1 as a positive control for disabling a real antiviral system. The armed virus destroyed host microRNAs efficiently in fibroblasts, primary bone marrow-derived macrophages and mouse lung and gained no replication advantage in any of them. In wild-type mice it was attenuated by about a log, attributed by messenger RNA sequencing to derepression of interferon-stimulated transcripts normally held down by microRNAs, and in mice lacking both type I and type III interferon receptors all three viruses reached comparable titres, which removes the objection that a silencing contribution might be hidden beneath interferon. The authors state that absence of an activity is difficult to prove and treat the result as a strong argument rather than a demonstration.\n\nAguado 2015 then established what microRNAs do during the response. Delivering VP55 from a replication-incompetent adenovirus removed roughly ninety percent of abundant microRNAs from primary human fibroblasts within a day without inducing interferon-stimulated genes. Only 12 of 1,548 genes induced by double-stranded RNA changed, and 12 of 179 induced by six hours of interferon beta, while nine days of depletion changed more than 1,700 transcripts dominated by chemokines and cytokines, with IFIH1, IRF3, IRF7, RELA, RELB, IFNB, IFNAR1, STAT2 and IRF9 unchanged even then. MicroRNA function during infection is therefore confined to cytokine output rather than to the intrinsic antiviral program, and conflicting reports are reconciled by a timescale argument, since assays run over hours will find nothing even where real targets exist.\n\nThe complementary positive result is what makes the negative one interpretable. Benitez 2015 inserted perfectly complementary target sites for host microRNAs into influenza A virus, converting resident microRNAs into cleaving guides, and separately had the virus encode a small interfering RNA against its own nucleoprotein segment. A five-site virus grew in embryonated eggs but produced no plaques and no detectable nucleoprotein in mammalian cells and caused no morbidity in mice at 25,000 plaque-forming units, including in animals lacking the type I interferon receptor, a dose the authors note is more than 2,500 times the lethal dose 50 in that background. Protection there cannot be attributed to interferon, so the simplest explanation for the historical substitution is removed. The authors frame this as a possibility claim, that chordates could have used RNA interference in place of interferon, and state explicitly that the paper does not explain why they did not. Neither half of the pair supports a conclusion on its own, and the reconstructed system departs from an endogenous one in that guides are present before the virus arrives and targets are concentrated at one internal site. The evolutionary explanation remains a hypothesis by the explicit statement of tenOever 2016, and Backes 2014 lists the absence of stem cell work among its own limitations.\n\n**Substantiated by**\n- 2012-backes-degradation-of-host-micrornas-by-p, identifies VP55 as sufficient to tail and destroy RISC-loaded microRNAs and supplies the reagent the rest of the argument depends on\n- 2014-backes-the-mammalian-response-to-virus-in, shows that destroying host microRNAs gives a virus no fitness benefit, including in animals lacking both interferon receptors\n- 2015-aguado-microrna-function-is-limited-to-cy, shows that removing microRNAs leaves the intrinsic antiviral program intact and derepresses chemokines and cytokines instead\n- 2015-benitez-engineered-mammalian-rnai-can-elic, shows that a reconstructed slicing defence protects mice with no contribution from type I interferon signalling\n- 2013-tenoever-rna-viruses-and-the-host-microrna-, argues from copy number, silencing capacity and kinetics that chordate microRNAs cannot be antiviral\n- 2013-cullen-is-rna-interference-a-physiologica, led by Bryan Cullen, sets the evidentiary criteria and states why the positive claims then available did not meet them",
    "supporting_publications": [
      {
        "id": "2012-backes-degradation-of-host-micrornas-by-p",
        "url": "https://tenoeverlab.us/publications/2012-backes-degradation-of-host-micrornas-by-p/",
        "evidence": "identifies VP55 as sufficient to tail and destroy RISC-loaded microRNAs and supplies the reagent the rest of the argument depends on"
      },
      {
        "id": "2014-backes-the-mammalian-response-to-virus-in",
        "url": "https://tenoeverlab.us/publications/2014-backes-the-mammalian-response-to-virus-in/",
        "evidence": "shows that destroying host microRNAs gives a virus no fitness benefit, including in animals lacking both interferon receptors"
      },
      {
        "id": "2015-aguado-microrna-function-is-limited-to-cy",
        "url": "https://tenoeverlab.us/publications/2015-aguado-microrna-function-is-limited-to-cy/",
        "evidence": "shows that removing microRNAs leaves the intrinsic antiviral program intact and derepresses chemokines and cytokines instead"
      },
      {
        "id": "2015-benitez-engineered-mammalian-rnai-can-elic",
        "url": "https://tenoeverlab.us/publications/2015-benitez-engineered-mammalian-rnai-can-elic/",
        "evidence": "shows that a reconstructed slicing defence protects mice with no contribution from type I interferon signalling"
      },
      {
        "id": "2013-tenoever-rna-viruses-and-the-host-microrna-",
        "url": "https://tenoeverlab.us/publications/2013-tenoever-rna-viruses-and-the-host-microrna-/",
        "evidence": "argues from copy number, silencing capacity and kinetics that chordate microRNAs cannot be antiviral"
      },
      {
        "id": "2013-cullen-is-rna-interference-a-physiologica",
        "url": "https://tenoeverlab.us/publications/2013-cullen-is-rna-interference-a-physiologica/",
        "evidence": "led by Bryan Cullen, sets the evidentiary criteria and states why the positive claims then available did not meet them"
      }
    ]
  },
  {
    "id": "claim-09",
    "statement": "Escape from RNA-guided targeting is set by whether a virus can recombine, and where it cannot, a host editing enzyme can supply the escape",
    "status": "lab-led",
    "research_areas": [
      "viral-populations-evolution",
      "small-rna-antiviral-defense"
    ],
    "substantiated_by": [
      {
        "slug": "2015-benitez-engineered-mammalian-rnai-can-elic",
        "contributes": "fixes the design parameters and establishes that escape occurs on the guide side rather than at the target"
      },
      {
        "slug": "2018-aguado-homologous-recombination-is-an-int",
        "contributes": "makes the pressure comparative across four families and identifies template switching as the escape requirement with a single polymerase substitution"
      },
      {
        "slug": "2023-uhl-adar1-biology-can-hinder-effective",
        "contributes": "shows a host editing enzyme supplying escape to a virus that cannot recombine"
      },
      {
        "slug": "2012-pham-replication-in-cells-of-hematopoie",
        "contributes": "shows total cassette excision under sustained pressure in an animal"
      }
    ],
    "url": "/discoveries/recombination-and-rna-editing/",
    "narrative_markdown": "**Status** lab-led\n**Areas** viral-populations-evolution, small-rna-antiviral-defense\n\nWhether a virus survives a defence is normally studied one virus and one defence at a time, and the answer is usually an encoded antagonist. That leaves a prior question unasked. Given a pressure no virus in the comparison has evolved to antagonise, which feature of a replication strategy decides whether escape is available at all. Vertebrate cells make the experiment possible, because a vertebrate virus has no reason to carry a suppressor of silencing while the machinery is still present.\n\nBenitez 2015 supplied the pressure and the first escape result, which is negative and set up everything after it. Across several designs, including one carrying a single target site, escape arose only by destroying guide production through deletion or excision of the hairpin, and no virus was recovered that had mutated the target sequence itself. Aguado 2018 made the pressure comparative, placing a cassette of perfectly complementary sites for five ubiquitous microRNAs in an essential transcript of six viruses from four families, with a reverse-orientation cassette of identical composition as the sequence-matched control and RNase III deficient fibroblasts as the silencing-off condition. A genome-wide CRISPR screen confirmed that the pressure runs through the microRNA machinery alone, recovering Drosha, Dicer, DGCR8, Argonaute 2, XPO5, TP53 and miR-21 and implicating no interferon genes. Sendai virus and influenza A virus lost more than five logs and were cleared, while Sindbis virus, a Semliki Forest virus chimera and poliovirus were suppressed and then recovered by precise excision. Poliovirus escaped despite making all its proteins from one RNA, so a multi-transcript genome organisation is not the requirement. The causal test is a single polymerase substitution, since poliovirus carrying D79H grew normally without the pressure, could not excise the cassette, and was undetectable by passage four. Template switching rather than polarity is therefore the requirement.\n\nUhl 2023 returned to the case Aguado 2018 had left as a dead end, on the argument that negative-sense RNA viruses do exist in hosts with functional antiviral silencing. Holding infections without passage so rare events are not diluted, and reading escape in 96-well format, a five-target Sendai virus escaped at six to eight days in roughly eight percent of wells. The signature was neither excision nor scattered point mutation but dense adenosine to guanosine changes confined to the target sites. Knockout of ADAR1 in a STAT1 deficient background abolished escape in all 96 wells and adenoviral reconstitution restored it, so the selective pressure is relieved by a host enzyme and the escape is not a viral adaptation at all. The same occurred with the cassette moved to the phosphoprotein gene, with editing on the antigenome, and in canine and mouse cells.\n\nThe practical consequence is that any design relying on microRNA targeting erodes in ways that differ by virus class, which Uhl 2023 states directly for vector design. Pham 2012 shows the same erosion in an animal, where dengue virus recovered from spleen carried no intact targeted genomes, only variants that had excised the whole cassette. What is not established is how ADAR1 comes to edit those particular sequences, with a duplex substrate model and a direct recruitment model both left open and the rarity of escape putting biochemistry out of reach. The route does not generalise, since a five-target influenza A virus under the same regime showed neither editing nor escape, which is unexplained. The proposal in Aguado 2018 that inefficient recombination explains the lower representation of negative-strand viruses across the tree of life is flagged as speculation by its authors, and the attribution of poor recombination to encapsidation is cited reasoning rather than a result.\n\n**Substantiated by**\n- 2015-benitez-engineered-mammalian-rnai-can-elic, fixes the design parameters and establishes that escape occurs on the guide side rather than at the target\n- 2018-aguado-homologous-recombination-is-an-int, makes the pressure comparative across four families and identifies template switching as the escape requirement with a single polymerase substitution\n- 2023-uhl-adar1-biology-can-hinder-effective, shows a host editing enzyme supplying escape to a virus that cannot recombine\n- 2012-pham-replication-in-cells-of-hematopoie, shows total cassette excision under sustained pressure in an animal",
    "supporting_publications": [
      {
        "id": "2015-benitez-engineered-mammalian-rnai-can-elic",
        "url": "https://tenoeverlab.us/publications/2015-benitez-engineered-mammalian-rnai-can-elic/",
        "evidence": "fixes the design parameters and establishes that escape occurs on the guide side rather than at the target"
      },
      {
        "id": "2018-aguado-homologous-recombination-is-an-int",
        "url": "https://tenoeverlab.us/publications/2018-aguado-homologous-recombination-is-an-int/",
        "evidence": "makes the pressure comparative across four families and identifies template switching as the escape requirement with a single polymerase substitution"
      },
      {
        "id": "2023-uhl-adar1-biology-can-hinder-effective",
        "url": "https://tenoeverlab.us/publications/2023-uhl-adar1-biology-can-hinder-effective/",
        "evidence": "shows a host editing enzyme supplying escape to a virus that cannot recombine"
      },
      {
        "id": "2012-pham-replication-in-cells-of-hematopoie",
        "url": "https://tenoeverlab.us/publications/2012-pham-replication-in-cells-of-hematopoie/",
        "evidence": "shows total cassette excision under sustained pressure in an animal"
      }
    ]
  },
  {
    "id": "claim-10",
    "statement": "Encoding a perturbation in a virus makes tropism, host restriction and viral output experimental variables inside an intact animal",
    "status": "lab-led for Perez 2009, Varble 2010, Langlois 2012 in PNAS, Langlois 2012 in Molecular Therapy, Pham 2012, Varble 2013, Schmid 2014, Benitez 2015 on in vivo screening, Møller 2018 and the tenOever 2019 review, and co-led for Langlois 2013, whose ferret transmission work sits with the Perez and García-Sastre groups. Daniloski 2021 in Cell is co-led with the Sanjana laboratory",
    "research_areas": [
      "programmable-virology",
      "innate-immune-signaling"
    ],
    "substantiated_by": [
      {
        "slug": "2009-perez-microrna-mediated-species-specific",
        "contributes": "founds the design and the control set, and shows that infection leaves the silencing machinery available"
      },
      {
        "slug": "2012-langlois-hematopoietic-specific-targeting-o",
        "contributes": "converts attenuation into an instrument and locates much of the in vivo interferon response in a numerically minor compartment"
      },
      {
        "slug": "2012-pham-replication-in-cells-of-hematopoie",
        "contributes": "applies the subtraction to dengue dissemination and shows what escape looks like in an animal"
      },
      {
        "slug": "2013-langlois-microrna-based-strategy-to-mitigat",
        "contributes": "moves the element into engineered noncoding space and demonstrates a host-conditional containment layer at no measurable fitness cost"
      },
      {
        "slug": "2018-m-ller-mirna-mediated-targeting-of-human-",
        "contributes": "extends the element to a large DNA virus and turns it into lineage-restricted conditional genetics"
      },
      {
        "slug": "2010-varble-engineered-rna-viral-synthesis-of-",
        "contributes": "removes the prohibition on an RNA virus encoding a microRNA and creates the segment 8 insertion space the later work occupies"
      },
      {
        "slug": "2012-langlois-in-vivo-delivery-of-cytoplasmic-rn",
        "contributes": "delivers a functional microRNA to five organs and contains the proposal that becomes the screening platform"
      },
      {
        "slug": "2014-schmid-a-versatile-rna-vector-for-deliver",
        "contributes": "makes the vector replication-incompetent and its output adjustable by the host silencing machinery"
      },
      {
        "slug": "2013-varble-an-in-vivo-rnai-screening-approach",
        "contributes": "implements selection inside an animal as the assay and supplies the neutral drift control that makes it interpretable"
      },
      {
        "slug": "2015-benitez-in-vivo-rnai-screening-identifies-",
        "contributes": "recovers MDA5 and shows that a sensor can be required for restriction without being required for interferon beta induction"
      },
      {
        "slug": "2019-tenoever-synthetic-virology-building-viruse",
        "contributes": "states the premise and sorts the designs by what each can ask and whether it preserves viral fitness"
      },
      {
        "slug": "2021-daniloski-identification-of-required-host-fa",
        "contributes": "co-led with the Sanjana laboratory, applies survival as selection at genome scale in culture and converges on endosomal machinery"
      }
    ],
    "url": "/discoveries/viruses-as-experimental-tools/",
    "narrative_markdown": "**Status** lab-led for Perez 2009, Varble 2010, Langlois 2012 in PNAS, Langlois 2012 in Molecular Therapy, Pham 2012, Varble 2013, Schmid 2014, Benitez 2015 on in vivo screening, Møller 2018 and the tenOever 2019 review, and co-led for Langlois 2013, whose ferret transmission work sits with the Perez and García-Sastre groups. Daniloski 2021 in Cell is co-led with the Sanjana laboratory\n**Areas** programmable-virology, innate-immune-signaling\n\nAsking what one cell type contributes to an infection is normally done by removing that cell type or a gene it needs, and both perturbations remove far more than the infection. A depleted compartment is not an animal in which the compartment is present but uninfected. Screens for host factors had converged on cultured transformed cells with surrogate readouts, and meta-analyses of nine genome-wide influenza screens found little overlap beyond the vacuolar ATPase subunits. The move that answers both problems is to put the perturbation in the pathogen, where it travels with the infection, reaches whatever cells the pathogen reaches, and is subject to the same selection.\n\nThe enabling element is a fully complementary target site for a host microRNA placed in a viral transcript, which turns a resident microRNA into a virus-specific silencing guide. Perez 2009 built such sites into the influenza nucleoprotein open reading frame at positions preserving the side chain class of the encoded amino acid, using miR-93 because published profiles place it in mouse and human and not chicken, and obtained a virus attenuated by more than two logs in mice while reaching roughly 10^8 plaque-forming units per millilitre in eggs. Its control set, a pairing-disrupted parental strain, Dicer-deficient cells and an antimiR rescue, defines what such a virus must show before any phenotype can be read, and its report that neither influenza infection nor NS1 disturbs microRNA biogenesis or silencing in mammalian cells is the licensing observation for everything after it. Langlois 2012 in PNAS turned the design into an instrument, silencing influenza only in hematopoietic cells and finding that mice cleared the virus and made normal nucleoprotein- and polymerase acidic-specific CD8 T cell responses while whole lung interferon beta and IRF-7 induction fell, a deficit its authors state they cannot explain from the size of the compartment silenced. Pham 2012 ran the same subtraction against dengue dissemination. Langlois 2013 moved the sites into a duplicated packaging region so the safety layer costs no fitness and selected miR-192 from small RNA sequencing of the exact tissues that mattered, giving a virus causing no disease in mice at ten times a lethal dose while an H3N2 version transmitted in ferrets indistinguishably from controls. Møller 2018 made an essential cytomegalovirus gene conditionally dispensable, so IE2 could be studied in macrophages despite being required in the fibroblasts used for rescue, and found that essentiality determined in fibroblasts does not transfer to the myeloid lineage.\n\nThe reciprocal line had the virus produce small RNAs rather than respond to them. Varble 2010 removed the assumed prohibition on an RNA virus encoding a microRNA by splitting the overlapping NS1 and NEP reading frames of segment 8, so the hairpin is excised in the spliced lariat rather than from the genome, and mature miR-124 appeared within four hours at levels comparable to abundant endogenous microRNAs with growth matching wild type. Langlois 2012 in Molecular Therapy carried that to a cytoplasmic negative-sense vector, reaching an estimated 25,000 to 35,000 copies per cell and five organs after intravenous delivery, and Schmid 2014 made the vector replication-incompetent and its output adjustable by installing the miR-93-targeted nucleoprotein segment from Perez 2009. The screening format follows from the same space. Varble 2013 passaged roughly 10,000 hairpin-encoding viruses through mice with a matched barcode library quantifying how much apparent reproducibility a bottlenecked passage generates on its own, and recovered Zfx and Mga as transcriptional maintenance factors. Benitez 2015 changed the selective pressure to an NS1 mutant crippled by the host response itself, so silencing a gene that contributes to that response restores fitness directly, and recovered Ifih1 with more than fiftyfold enrichment in four independent screens, lost in Ifih1 knockout mice and absent in canine cells. That result revises something two prior studies had treated as settled, since interferon beta induction during influenza infection requires RIG-I and not MDA5, which Benitez 2015 confirms, and yet MDA5 is required for full induction of Irf7, OAS isoforms, Ifit1, Stat1 and Isg15 and its loss relieves restriction. An interferon-induction readout can miss a sensor's contribution.\n\nBoundaries are substantial and mostly stated by the papers themselves. MicroRNA silencing is potent but incomplete, so a lineage-restricted phenotype is a strong knockdown and not a null, and because miR-142 is expressed across hematopoietic lineages none of the compartment papers can assign a phenotype to one subset. Escape is bounded rather than excluded, since Perez 2009 and Langlois 2013 recovered no revertants within their sampling while Pham 2012 shows total excision under pressure. The screens are cell-autonomous, cannot report on constitutively abundant restriction factors, which the papers demonstrate with RIG-I itself, and their target assignment in Varble 2013 is computational. The delivery line reached intranasal delivery in Schmid 2014 with in vivo silencing left to future studies and no later paper here demonstrates it, the biocontainment proposal to generalise to filoviruses, coronaviruses and henipaviruses was not taken up, and tenOever 2019 records that only the screening application became a sustained program. The two CRISPR screens in this area, Han 2018 led by the Manicassamy laboratory and Daniloski 2021 co-led with the Sanjana laboratory, share the logic of fitness as readout but sit in cell culture, which is the constraint the animal platform was built to escape, so their relation to this work is convergence rather than descent.\n\n**Substantiated by**\n- 2009-perez-microrna-mediated-species-specific, founds the design and the control set, and shows that infection leaves the silencing machinery available\n- 2012-langlois-hematopoietic-specific-targeting-o, converts attenuation into an instrument and locates much of the in vivo interferon response in a numerically minor compartment\n- 2012-pham-replication-in-cells-of-hematopoie, applies the subtraction to dengue dissemination and shows what escape looks like in an animal\n- 2013-langlois-microrna-based-strategy-to-mitigat, moves the element into engineered noncoding space and demonstrates a host-conditional containment layer at no measurable fitness cost\n- 2018-m-ller-mirna-mediated-targeting-of-human-, extends the element to a large DNA virus and turns it into lineage-restricted conditional genetics\n- 2010-varble-engineered-rna-viral-synthesis-of-, removes the prohibition on an RNA virus encoding a microRNA and creates the segment 8 insertion space the later work occupies\n- 2012-langlois-in-vivo-delivery-of-cytoplasmic-rn, delivers a functional microRNA to five organs and contains the proposal that becomes the screening platform\n- 2014-schmid-a-versatile-rna-vector-for-deliver, makes the vector replication-incompetent and its output adjustable by the host silencing machinery\n- 2013-varble-an-in-vivo-rnai-screening-approach, implements selection inside an animal as the assay and supplies the neutral drift control that makes it interpretable\n- 2015-benitez-in-vivo-rnai-screening-identifies-, recovers MDA5 and shows that a sensor can be required for restriction without being required for interferon beta induction\n- 2019-tenoever-synthetic-virology-building-viruse, states the premise and sorts the designs by what each can ask and whether it preserves viral fitness\n- 2021-daniloski-identification-of-required-host-fa, co-led with the Sanjana laboratory, applies survival as selection at genome scale in culture and converges on endosomal machinery",
    "supporting_publications": [
      {
        "id": "2009-perez-microrna-mediated-species-specific",
        "url": "https://tenoeverlab.us/publications/2009-perez-microrna-mediated-species-specific/",
        "evidence": "founds the design and the control set, and shows that infection leaves the silencing machinery available"
      },
      {
        "id": "2012-langlois-hematopoietic-specific-targeting-o",
        "url": "https://tenoeverlab.us/publications/2012-langlois-hematopoietic-specific-targeting-o/",
        "evidence": "converts attenuation into an instrument and locates much of the in vivo interferon response in a numerically minor compartment"
      },
      {
        "id": "2012-pham-replication-in-cells-of-hematopoie",
        "url": "https://tenoeverlab.us/publications/2012-pham-replication-in-cells-of-hematopoie/",
        "evidence": "applies the subtraction to dengue dissemination and shows what escape looks like in an animal"
      },
      {
        "id": "2013-langlois-microrna-based-strategy-to-mitigat",
        "url": "https://tenoeverlab.us/publications/2013-langlois-microrna-based-strategy-to-mitigat/",
        "evidence": "moves the element into engineered noncoding space and demonstrates a host-conditional containment layer at no measurable fitness cost"
      },
      {
        "id": "2018-m-ller-mirna-mediated-targeting-of-human-",
        "url": "https://tenoeverlab.us/publications/2018-m-ller-mirna-mediated-targeting-of-human-/",
        "evidence": "extends the element to a large DNA virus and turns it into lineage-restricted conditional genetics"
      },
      {
        "id": "2010-varble-engineered-rna-viral-synthesis-of-",
        "url": "https://tenoeverlab.us/publications/2010-varble-engineered-rna-viral-synthesis-of-/",
        "evidence": "removes the prohibition on an RNA virus encoding a microRNA and creates the segment 8 insertion space the later work occupies"
      },
      {
        "id": "2012-langlois-in-vivo-delivery-of-cytoplasmic-rn",
        "url": "https://tenoeverlab.us/publications/2012-langlois-in-vivo-delivery-of-cytoplasmic-rn/",
        "evidence": "delivers a functional microRNA to five organs and contains the proposal that becomes the screening platform"
      },
      {
        "id": "2014-schmid-a-versatile-rna-vector-for-deliver",
        "url": "https://tenoeverlab.us/publications/2014-schmid-a-versatile-rna-vector-for-deliver/",
        "evidence": "makes the vector replication-incompetent and its output adjustable by the host silencing machinery"
      },
      {
        "id": "2013-varble-an-in-vivo-rnai-screening-approach",
        "url": "https://tenoeverlab.us/publications/2013-varble-an-in-vivo-rnai-screening-approach/",
        "evidence": "implements selection inside an animal as the assay and supplies the neutral drift control that makes it interpretable"
      },
      {
        "id": "2015-benitez-in-vivo-rnai-screening-identifies-",
        "url": "https://tenoeverlab.us/publications/2015-benitez-in-vivo-rnai-screening-identifies-/",
        "evidence": "recovers MDA5 and shows that a sensor can be required for restriction without being required for interferon beta induction"
      },
      {
        "id": "2019-tenoever-synthetic-virology-building-viruse",
        "url": "https://tenoeverlab.us/publications/2019-tenoever-synthetic-virology-building-viruse/",
        "evidence": "states the premise and sorts the designs by what each can ask and whether it preserves viral fitness"
      },
      {
        "id": "2021-daniloski-identification-of-required-host-fa",
        "url": "https://tenoeverlab.us/publications/2021-daniloski-identification-of-required-host-fa/",
        "evidence": "co-led with the Sanjana laboratory, applies survival as selection at genome scale in culture and converges on endosomal machinery"
      }
    ]
  },
  {
    "id": "claim-11",
    "statement": "Mammalian transmission of influenza founds a new infection from very few genomes, and the restriction lies in the recipient rather than in the virus",
    "status": "lab-led for Varble 2014. McCune 2020 is collaborative and led by the Pfeiffer laboratory at the University of Texas Southwestern, where all mouse work was done, and Muñoz-Moreno 2019 is collaborative and led by the García-Sastre laboratory, with the tenOever contribution in both being the barcoded library method and supervision",
    "research_areas": [
      "viral-populations-evolution",
      "influenza-genome-regulation"
    ],
    "substantiated_by": [
      {
        "slug": "2014-varble-influenza-a-virus-transmission-bot",
        "contributes": "measures bottleneck size across routes and recipients and locates the restriction in the recipient rather than in viral genetics"
      },
      {
        "slug": "2020-mccune-rapid-dissemination-and-monopoliza",
        "contributes": "led by the Pfeiffer laboratory, shows that diversity in an enteric infection collapses after replication rather than at the barrier"
      },
      {
        "slug": "2019-munoz-moreno-viral-fitness-landscapes-in-divers",
        "contributes": "led by the García-Sastre laboratory, shows that phylogenetic proximity predicts NS1 phenotype poorly and places the selective filter in innate signalling"
      }
    ],
    "url": "/discoveries/influenza-transmission-bottlenecks/",
    "narrative_markdown": "**Status** lab-led for Varble 2014. McCune 2020 is collaborative and led by the Pfeiffer laboratory at the University of Texas Southwestern, where all mouse work was done, and Muñoz-Moreno 2019 is collaborative and led by the García-Sastre laboratory, with the tenOever contribution in both being the barcoded library method and supervision\n**Areas** viral-populations-evolution, influenza-genome-regulation\n\nBottleneck size had mostly been inferred from consensus sequence divergence or from surveys of natural infection, which cannot separate a restriction on which genomes enter from one acting later, and cannot say whether survivors survive because of what they encode or by chance. Varble 2014 solved the measurement problem by building more than one hundred influenza A viruses differing only by a 22 nucleotide barcode carried in the engineered intergenic region of a split NS segment, and by testing the neutrality assumption against wild type growth curves, individually amplified clones and duplicate sequencing before drawing conclusions from it.\n\nPassing that library through a graded series of settings gave directly comparable numbers. Canine and human cell monolayers imposed no detectable bottleneck. Embryonated eggs collapsed the library to between five and thirteen clones. Guinea pig recipients infected across cages carried two to five clones, ferret contact recipients carried seven to twenty four against seventy one to one hundred in donors, and airborne transmission reduced the recovered population to as few as two barcodes. Two further results carry more weight than the counts. Egg passage was accompanied by convergent hemagglutinin change at residues associated with avian receptor specificity while mammalian transmission showed no such convergence, which separates genetically driven selection during host adaptation from sequence-independent sampling. And three guinea pigs cocaged with one donor all became infected and all carried different barcode sets despite identical exposure, which places the restriction at the recipient. Transmission probability correlated with a clone's abundance in donor nasal wash and not in donor bronchus.\n\nThe consequence for risk assessment is stated in the paper. If airborne transmission can be founded by as few as two genomes, a phenotype requiring several mutations and present at low frequency in a donor is unlikely to be carried intact into a new host, which Varble 2014 connects to why an airborne transmissible H5N1 has not emerged despite repeated human infections. Two extensions were led elsewhere. McCune 2020 recovered all 135 barcodes of a coxsackievirus B3 library from the upper gastrointestinal tract at 7.5 and 19 hours and found three or fewer barcodes dominating every tissue by 48 to 72 hours, using neutral red labelling to show that diverse members had genuinely replicated first, so the loss of diversity in that system is a post-replication event rather than a gate at the barrier. Muñoz-Moreno 2019 competed 107 barcoded viruses carrying 56 natural NS1 sequences in a common backbone across dog cells, human cells, eggs and mice and found allele B overrepresented in every substrate, clusters sharing fitness profiles despite substantial amino acid divergence, and Stat1 deficiency flattening much of the spread where Rag1 deficiency did not, so phylogenetic position predicts phenotype poorly for this gene and the selective filter sits in early innate signalling.\n\nWhat is not established is the barrier in the recipient that performs the sampling, which no publication in this corpus identifies, and Varble 2014 leaves open whether an additional selection step occurs at secretion. How fitness is maintained across repeated severe bottlenecks is unresolved. Muñoz-Moreno 2019 establishes no molecular mechanism for any individual fitness difference. Every measurement rests on engineered viruses carrying inserted sequence in cultured cells and animal models, so generalisation to unmodified viruses in natural infection is an extrapolation. Within this laboratory the transmission bottleneck work was not returned to, and the honest description is that the method travelled further than the question did.\n\n**Substantiated by**\n- 2014-varble-influenza-a-virus-transmission-bot, measures bottleneck size across routes and recipients and locates the restriction in the recipient rather than in viral genetics\n- 2020-mccune-rapid-dissemination-and-monopoliza, led by the Pfeiffer laboratory, shows that diversity in an enteric infection collapses after replication rather than at the barrier\n- 2019-munoz-moreno-viral-fitness-landscapes-in-divers, led by the García-Sastre laboratory, shows that phylogenetic proximity predicts NS1 phenotype poorly and places the selective filter in innate signalling",
    "supporting_publications": [
      {
        "id": "2014-varble-influenza-a-virus-transmission-bot",
        "url": "https://tenoeverlab.us/publications/2014-varble-influenza-a-virus-transmission-bot/",
        "evidence": "measures bottleneck size across routes and recipients and locates the restriction in the recipient rather than in viral genetics"
      },
      {
        "id": "2020-mccune-rapid-dissemination-and-monopoliza",
        "url": "https://tenoeverlab.us/publications/2020-mccune-rapid-dissemination-and-monopoliza/",
        "evidence": "led by the Pfeiffer laboratory, shows that diversity in an enteric infection collapses after replication rather than at the barrier"
      },
      {
        "id": "2019-munoz-moreno-viral-fitness-landscapes-in-divers",
        "url": "https://tenoeverlab.us/publications/2019-munoz-moreno-viral-fitness-landscapes-in-divers/",
        "evidence": "led by the García-Sastre laboratory, shows that phylogenetic proximity predicts NS1 phenotype poorly and places the selective filter in innate signalling"
      }
    ]
  },
  {
    "id": "claim-12",
    "statement": "The inflammatory character of SARS-CoV-2 infection is something the virus requires rather than something it fails to suppress",
    "status": "lab-led",
    "research_areas": [
      "pandemic-host-response",
      "innate-immune-signaling"
    ],
    "substantiated_by": [
      {
        "slug": "2020-blanco-melo-imbalanced-host-response-to-sars-c",
        "contributes": "establishes the imbalanced response across six viruses and four levels of system and separates the interferon and chemokine arms experimentally"
      },
      {
        "slug": "2021-nilsson-payant-the-nf-b-transcriptional-footprint",
        "contributes": "shows that infection engages NF-kappa B and not the interferon factors and that NF-kappa B-driven transcription is required for replication"
      }
    ],
    "url": "/discoveries/sars-cov-2-inflammatory-dependency/",
    "narrative_markdown": "**Status** lab-led\n**Areas** pandemic-host-response, innate-immune-signaling\n\nIn the first weeks of 2020 there was no matched description of what SARS-CoV-2 does to a host cell. Blanco-Melo 2020 placed the virus alongside SARS-CoV-1, MERS-CoV, influenza A virus, human parainfluenza virus 3 and respiratory syncytial virus in the same systems and repeated the question at four levels of biological system. The recurring pattern was low type I and type III interferon with only a subset of interferon-stimulated genes induced, alongside pronounced chemokine and interleukin 6 expression, reproduced in cell lines, primary bronchial epithelium, ferrets, post-mortem lung and patient serum. Ruxolitinib abolished interferon-stimulated gene induction while leaving chemokine induction largely intact, which is the direct evidence that the inflammatory arm does not require interferon signalling, and interferon beta pretreatment restricted the virus, so the low output is not resistance.\n\nReading that imbalance as a failure of viral control assumes the virus would suppress the cytokine arm if it could. Nilsson-Payant 2021 on the NF-kappa B footprint tested the opposite. The dominant early signature in ACE2-expressing A549 cells was tumour necrosis factor alpha signalling through NF-kappa B, with no interferon signature and no STAT1 or IRF3 phosphorylation, concentrated by single-cell sequencing in infected rather than bystander cells, with chromatin accessibility opening at sites enriched for REL, RELA and NFKB1 motifs at distal regulatory elements. Silencing RelA reduced and silencing NF-kappa B1 abolished nucleocapsid protein, and RELA knockout cells were rescued by a chimeric RelA DNA-binding domain fused to a VPR activator while the equivalent IRF3 construct restricted the virus, which places the requirement at the level of NF-kappa B-driven transcription rather than the protein itself. Four chemically distinct inhibitors reduced infection in vitro.\n\nWhat is now known is that the inflammatory arm of this infection is a viral dependency, which makes replication and inflammation potentially the same target rather than opposing ones. What is not known is which NF-kappa B target genes the virus requires, and whether the dependency holds in an animal, since the authors state they could not reproduce the inhibitor effect in their hamster model and note the absence of approved NF-kappa B inhibitors. No viral product responsible for the low interferon phenotype is identified anywhere in this corpus, and Blanco-Melo 2020 declines to adjudicate between an antagonist overcome at high multiplicity and high multiplicity generating patterns that may not form physiologically. Its human tissue analysis rests on two post-mortem COVID-19 lungs against two healthy lungs and its serum study on 24 cases and 24 controls, comparison viruses were run at differing multiplicities and durations, and the claim that this pattern drives COVID-19 pathology is an interpretation of correlated observations rather than a demonstrated causal chain.\n\n**Substantiated by**\n- 2020-blanco-melo-imbalanced-host-response-to-sars-c, establishes the imbalanced response across six viruses and four levels of system and separates the interferon and chemokine arms experimentally\n- 2021-nilsson-payant-the-nf-b-transcriptional-footprint, shows that infection engages NF-kappa B and not the interferon factors and that NF-kappa B-driven transcription is required for replication",
    "supporting_publications": [
      {
        "id": "2020-blanco-melo-imbalanced-host-response-to-sars-c",
        "url": "https://tenoeverlab.us/publications/2020-blanco-melo-imbalanced-host-response-to-sars-c/",
        "evidence": "establishes the imbalanced response across six viruses and four levels of system and separates the interferon and chemokine arms experimentally"
      },
      {
        "id": "2021-nilsson-payant-the-nf-b-transcriptional-footprint",
        "url": "https://tenoeverlab.us/publications/2021-nilsson-payant-the-nf-b-transcriptional-footprint/",
        "evidence": "shows that infection engages NF-kappa B and not the interferon factors and that NF-kappa B-driven transcription is required for replication"
      }
    ]
  },
  {
    "id": "claim-13",
    "statement": "Interferon generated by airway replication circulates, primes distal organs and is what keeps SARS-CoV-2 respiratory",
    "status": "lab-led",
    "research_areas": [
      "pandemic-host-response",
      "innate-immune-signaling"
    ],
    "substantiated_by": [
      {
        "slug": "2021-hoagland-leveraging-the-antiviral-type-i-in",
        "contributes": "delivers the longitudinal multi-tissue atlas with an annotated Ifnb1 and shows local interferon lowering virus, pathology and transmission"
      },
      {
        "slug": "2023-carrau-delayed-engagement-of-host-defense",
        "contributes": "shows by three independent manipulations that airway-derived circulating interferon primes distal organs and restricts tropism"
      }
    ],
    "url": "/discoveries/airway-interferon-and-systemic-protection/",
    "narrative_markdown": "**Status** lab-led\n**Areas** pandemic-host-response, innate-immune-signaling\n\nIf the defining feature of this infection is a muted interferon response, the obvious inference is to supply the missing arm, and several lines of evidence made that attractive. Testing it required the full course of infection across tissues in a host where an unmodified clinical isolate causes progressive lower respiratory disease. It also required deciding what antiviral transcription away from the airway means, since it could report local infection or a signal arriving from elsewhere, and those readings imply different interventions.\n\nHoagland 2021 built the platform and the intervention together in golden hamsters, which are permissive without host genetic modification. Because Ifnb1 was unannotated in that genome, the authors assembled, cloned and functionally validated a candidate transcript, which is what made interferon biology readable in the species. Ten plaque-forming units sufficed to seed the lower respiratory tract and raising the inoculum a thousandfold did not increase replication, inflammation moved from upper to lower airway over several days, and olfactory bulb, brain and small intestine showed strong antiviral transcription at viral reads orders of magnitude below respiratory levels. Intranasal universal interferon alpha A/D, given before challenge or one day after, lowered infectious virus and proinflammatory transcripts, shifted the infiltrate away from neutrophils and prevented transmission in three of five exposed animals, with a double-stranded RNA mimetic giving comparable activity. The paper attributed the distal antiviral state speculatively to disseminated viral RNA.\n\nCarrau 2023 tested that attribution and reported for the alternative. Whole blood carried an interferon-stimulated gene signature with no interferon transcripts of its own, and a fibroblast bioassay detected roughly sixty units per millilitre of circulating interferon at one day. Three independent manipulations pointed the same way. Dexamethasone delayed airway induction without changing early lung titres and permitted infectious virus in liver, spleen, olfactory bulb and gastrointestinal tract with transient viremia. Intravenous inoculation bypassed the airway and produced productive infection of kidney, liver, spleen, heart and gastrointestinal tract. Prior airway infection before intravenous challenge reduced distal loads. Circulating interferon was detected only in animals with lung titres, whatever the route.\n\nTwo things are now known. Extrapulmonary interferon signalling is a protective output of the lung rather than evidence of distal infection, and how fast the airway engages determines where the virus can establish. This is also a recorded internal correction, since Hoagland 2021 proposed disseminated viral material and Carrau 2023 from the same laboratory found for circulating interferon. What is not established is any molecular mechanism. Circulating interferon was read by bioassay rather than measured directly, because hamster reagents were unavailable, and type I and type III were not separated. Dexamethasone is a broad suppressor and direct effects on distal organs cannot be excluded, the intravenous arm used a thousandfold higher dose so route and dose are not independent, and viremia was detectable only after amplification. Young animals that clear the virus represent neither age nor lethal disease, the intranasal interferon result carries no human dosing implication, and extension of the model to severe human COVID-19 or to Long Covid is offered by the authors as speculation.\n\n**Substantiated by**\n- 2021-hoagland-leveraging-the-antiviral-type-i-in, delivers the longitudinal multi-tissue atlas with an annotated Ifnb1 and shows local interferon lowering virus, pathology and transmission\n- 2023-carrau-delayed-engagement-of-host-defense, shows by three independent manipulations that airway-derived circulating interferon primes distal organs and restricts tropism",
    "supporting_publications": [
      {
        "id": "2021-hoagland-leveraging-the-antiviral-type-i-in",
        "url": "https://tenoeverlab.us/publications/2021-hoagland-leveraging-the-antiviral-type-i-in/",
        "evidence": "delivers the longitudinal multi-tissue atlas with an annotated Ifnb1 and shows local interferon lowering virus, pathology and transmission"
      },
      {
        "id": "2023-carrau-delayed-engagement-of-host-defense",
        "url": "https://tenoeverlab.us/publications/2023-carrau-delayed-engagement-of-host-defense/",
        "evidence": "shows by three independent manipulations that airway-derived circulating interferon primes distal organs and restricts tropism"
      }
    ]
  },
  {
    "id": "claim-14",
    "statement": "Respiratory infection leaves a persistent inflammatory program in tissues where no virus remains, and olfactory loss is produced in cells the virus never enters",
    "status": "co-led. Frere 2022 and Serafini 2023 are co-corresponding with the Zachariou laboratory, Zazhytska 2022 was led with the Lomvardas and Overdevest groups, and Heaton 2014 is co-led with Peter Palese and tenOever as joint senior and corresponding authors",
    "research_areas": [
      "pandemic-host-response",
      "innate-immune-signaling",
      "programmable-virology"
    ],
    "substantiated_by": [
      {
        "slug": "2014-heaton-long-term-survival-of-influenza-vi",
        "contributes": "shows that some airway cells survive productive influenza infection and remain inflammatory after clearance, and that removing them reduces damage"
      },
      {
        "slug": "2022-frere-sars-cov-2-infection-in-hamsters-a",
        "contributes": "benchmarks against pandemic influenza and isolates what persists in the olfactory bulb at 31 days with no detectable virus"
      },
      {
        "slug": "2022-zazhytska-non-cell-autonomous-disruption-of-",
        "contributes": "shows nuclear architecture holding olfactory receptor genes dissipating in neurons the virus does not enter, reproducible with virus-free serum"
      },
      {
        "slug": "2023-serafini-sars-cov-2-airway-infection-result",
        "contributes": "extends the pattern to sensory ganglia and couples a late neuropathic transcriptome to returning hypersensitivity"
      }
    ],
    "url": "/discoveries/persistent-inflammation-and-olfactory-loss/",
    "narrative_markdown": "**Status** co-led. Frere 2022 and Serafini 2023 are co-corresponding with the Zachariou laboratory, Zazhytska 2022 was led with the Lomvardas and Overdevest groups, and Heaton 2014 is co-led with Peter Palese and tenOever as joint senior and corresponding authors\n**Areas** pandemic-host-response, innate-immune-signaling, programmable-virology\n\nPersistent symptoms after COVID-19 were well documented clinically with no biological account and no small animal system. Two things were needed. A comparator, because an inflammatory change a month after a severe respiratory infection means nothing until it is known whether another respiratory virus leaves the same mark, and a way to ask how a tissue the virus barely enters changes what it does. The problem had a precedent in influenza. Every label for an infected cell reports on a viral product and therefore decays, so whether any cell survives a productive infection and what it then does could not be asked until Heaton 2014 put Cre recombinase on the PB2 segment and marked infected cells permanently in reporter mice. Marked cells persisted at 10 and 21 days after infectious virus was undetectable, were confined to the epithelium of larger airways, retained Cc10 as their only lineage marker, carried an amplified interferon-stimulated gene signature with elevated Cxcl10, Ccl20 and Ccl5, and their ablation reduced bronchiolar epithelial necrosis.\n\nFrere 2022 made the comparator a requirement, infecting hamsters with SARS-CoV-2 or 2009 pandemic H1N1 influenza at doses matched for peak titre and profiling lung, heart, kidney and six nervous system regions at peak, one week after clearance and at 31 days. The discipline of that design is that several findings which would have read as specific to SARS-CoV-2 turn out to be shared with influenza, including the acute interferon response across tissues, peribronchiolar metaplasia, renal tubular atrophy and loss of olfactory receptor transcripts. What survived was narrower. At 31 days the olfactory bulb of influenza animals had returned to baseline while SARS-CoV-2 animals retained interferon signatures, elevated CXCL10 and CCL5 and microglial and myeloid activation, with no viral RNA detectable and no difference in apoptotic nuclei, alongside altered behaviour at 26 days and correlated inflammatory programs in tissue from recovered human donors. Serafini 2023 found the same shape in the peripheral sensory nervous system, with viral nucleocapsid transcripts and Isg15 rising in dorsal root ganglia and spinal cord within a day while no infectious virus was recoverable from any neural tissue, followed at 31 days by 1065 differentially expressed genes of neuropathic character and returning mechanical hypersensitivity in both sexes.\n\nZazhytska 2022 supplied a route by which an infection reaches cells it does not enter. The virus infected sustentacular cells, which were transiently depleted and restored, while neuronal representation stayed constant. Uninfected olfactory sensory neurons nonetheless mounted an antiviral response and then lost expression of olfactory receptor genes and of the signal transduction machinery for odour detection, still absent ten days after clearance. In situ Hi-C showed that the long-range contacts among receptor gene clusters, which normally converge into specialised interchromosomal compartments, were reduced from one day and remained reduced at ten days, and ultraviolet-inactivated serum from infected animals given intranasally to naive animals for 12.5 hours reproduced the loss of contacts with no viral genome transferred. Human autopsy tissue showed the same receptor downregulation and, in sorted neuronal nuclei, the same loss of contacts.\n\nTaken together the corpus supports a general statement that much of the damage attributed to this virus is done by the host response rather than by infection of the damaged cells, and that statement is synthesis across these papers rather than a claim any one makes. What none of them establishes is causality. Frere 2022 does not link persistent brain inflammation to the behavioural change, offers residual defective genomes and barrier breach as untested alternatives, and notes that absence of virus at 31 days is a limit of its assays. Zazhytska 2022 did not identify the circulating molecule or the receiving neuronal pathway, did not test smell in either species, and states its nuclear memory proposal as a hypothesis, with human data resting on two control and four infected autopsies. Serafini 2023 describes the association between viral material and persistent hypersensitivity as correlative, and its nominated target ILF3 was validated in mouse pain models and never tested in infected animals. Heaton 2014 states that the link between the interferon-stimulated gene signature of surviving club cells and their survival is correlative, and its ablation removes all marked survivors rather than club cells specifically.\n\n**Substantiated by**\n- 2014-heaton-long-term-survival-of-influenza-vi, shows that some airway cells survive productive influenza infection and remain inflammatory after clearance, and that removing them reduces damage\n- 2022-frere-sars-cov-2-infection-in-hamsters-a, benchmarks against pandemic influenza and isolates what persists in the olfactory bulb at 31 days with no detectable virus\n- 2022-zazhytska-non-cell-autonomous-disruption-of-, shows nuclear architecture holding olfactory receptor genes dissipating in neurons the virus does not enter, reproducible with virus-free serum\n- 2023-serafini-sars-cov-2-airway-infection-result, extends the pattern to sensory ganglia and couples a late neuropathic transcriptome to returning hypersensitivity",
    "supporting_publications": [
      {
        "id": "2014-heaton-long-term-survival-of-influenza-vi",
        "url": "https://tenoeverlab.us/publications/2014-heaton-long-term-survival-of-influenza-vi/",
        "evidence": "shows that some airway cells survive productive influenza infection and remain inflammatory after clearance, and that removing them reduces damage"
      },
      {
        "id": "2022-frere-sars-cov-2-infection-in-hamsters-a",
        "url": "https://tenoeverlab.us/publications/2022-frere-sars-cov-2-infection-in-hamsters-a/",
        "evidence": "benchmarks against pandemic influenza and isolates what persists in the olfactory bulb at 31 days with no detectable virus"
      },
      {
        "id": "2022-zazhytska-non-cell-autonomous-disruption-of-",
        "url": "https://tenoeverlab.us/publications/2022-zazhytska-non-cell-autonomous-disruption-of-/",
        "evidence": "shows nuclear architecture holding olfactory receptor genes dissipating in neurons the virus does not enter, reproducible with virus-free serum"
      },
      {
        "id": "2023-serafini-sars-cov-2-airway-infection-result",
        "url": "https://tenoeverlab.us/publications/2023-serafini-sars-cov-2-airway-infection-result/",
        "evidence": "extends the pattern to sensory ganglia and couples a late neuropathic transcriptome to returning hypersensitivity"
      }
    ]
  }
]