The Capicua and ATXN1L repressor complex binds an eight-nucleotide motif at interferon and interferon-stimulated gene loci to hold them repressed during homeostasis in human and mouse cells, and is degraded through EGFR-MAPK signaling early in respiratory viral entry, which relieves that repression.
Escape of a microRNA-targeted Sendai virus from engineered antiviral RNA interference comes not from the virus but from host ADAR1, whose adenosine to inosine editing destroys the target sites, and human ADAR1 also suppresses endogenous silencing in a plant.
Archaeal members of the L30 protein family, but not their orthologues from any other domain of life, block production of the spliced influenza A virus, influenza B virus and isavirus transcripts without measurably disturbing host splicing, identifying a shared and apparently noncanonical feature of orthomyxovirus splicing.
In golden hamsters, productive SARS-CoV-2 replication in the airways generates circulating type I and III interferon that primes every organ against infection, and blunting or bypassing that airway response permits viremia and productive infection of liver, kidney, spleen and brain.
An iterative, scarless and biallelic method for overwriting large mammalian genomic segments in mouse embryonic stem cells, used to build a recoded Trp53 locus and mice carrying the human ACE2 and TMPRSS2 loci in place of their mouse counterparts.
Intranasal SARS-CoV-2 infection of golden hamsters deposits viral RNA without infectious virus in dorsal root ganglia and spinal cord, producing a milder but longer-lasting mechanical hypersensitivity than influenza A virus and a neuropathic dorsal root ganglion transcriptome at 31 days, from which ILF3 emerges as an analgesic target validated in mouse pain models.
Stress granules restrain rather than amplify double-stranded RNA sensing, and cells lacking the granule nucleators G3BP1 and G3BP2, UBAP2L or PKR respond to double-stranded RNA with excessive RIG-I-like receptor, PKR and OAS activation and MAVS-dependent apoptosis.
Comparison of young and older golden hamsters infected with SARS-CoV-2 shows that age reduces the magnitude and duration of the innate response and of tissue repair, expands suppressor T cells and IL-17-driven neutrophil recruitment, and lowers germinal centre B cell frequency and neutralizing antibody potency without raising lung virus titres.
Kinase substrate specificity profiling assigns the phosphorylation cluster in the SARS-CoV-2 nucleocapsid SR-rich domain to a cascade initiated by SRPK1 and SRPK2 and extended by GSK-3 and casein kinase 1, whose inhibition suppresses coronavirus replication.
SARS-CoV-2 infection of the olfactory epithelium reorganizes the nuclear architecture of uninfected olfactory sensory neurons, dissipating the interchromosomal compartments that hold olfactory receptor genes and suppressing receptor and signal transduction transcription in both hamsters and human autopsy tissue.
Benchmarked against pandemic influenza in golden hamsters, SARS-CoV-2 uniquely sustains interferon signaling, chemokine production and myeloid activation in olfactory bulb and epithelium a month after clearance, alongside altered behavior and matching signatures in recovered human olfactory tissue.
Uncoupling the two steps of influenza A virus genome replication with viral promoter mutations shows that ANP32A is required for synthesis of both the complementary RNA intermediate and progeny genomic RNA, and that it acts on the actively replicating polymerase rather than the encapsidating one.
In golden hamsters, influenza A virus infection reduces SARS-CoV-2 replication during coinfection, after preinfection, and even one to two weeks after influenza has been cleared, while SARS-CoV-2 leaves influenza replication in vivo unchanged.
A microfluidic bronchial airway chip lined with differentiated human airway epithelium and pulmonary endothelium reproduces strain-dependent influenza virulence, cytokine output and neutrophil recruitment, and when drugs are delivered at clinically achievable blood concentrations under flow it separates candidates that work in cell lines from those that also work in hamsters challenged with SARS-CoV-2.
Targeted ancient DNA capture applied to skeletal remains from a Colonial hospital and chapel in Mexico City recovers three human parvovirus B19 genomes and one hepatitis B virus genome whose closest relatives are African strains, in hosts whose genetic ancestry and strontium isotope signatures point to African birth, giving direct molecular evidence that these viruses reached New Spain during the transatlantic slave trade.
A genome-scale CRISPR loss-of-function screen in ACE2-expressing human alveolar epithelial cells ranks every protein-coding gene by the effect of its loss on SARS-CoV-2 infection, converging on endosomal machinery, and links several top hits to increased cholesterol biosynthesis and, for RAB7A, to intracellular sequestration of ACE2.
Longitudinal tracking of antigen-specific lymphocytes in golden hamsters shows that memory from the founder strain of SARS-CoV-2 clears a beta variant rechallenge and that transferred memory T cells alone lower viral load, yet protected animals still infected every cohoused naive partner.
Longitudinal transcriptional and histological profiling of SARS-CoV-2 infected golden hamsters maps a wave of inflammation that reaches tissues with little or no productive replication, and shows that intranasal type I interferon given before or after challenge lowers viral load and disease burden.
Restricting nucleoprotein availability in negative-sense RNA virus infections both blocks full-length genome replication and increases production of aberrant replication products that are sensed through RIG-I and MAVS, so a strong interferon response accompanies rather than follows successful infection.
Human ocular surface tissue carries SARS-CoV-2 entry machinery and supports productive replication, with the limbus most permissive in both adult donor cells and stem cell derived whole-eye cultures, where infection drives NF-kB chemokine induction and blunted interferon signaling.
SARS-CoV-2 infection of human lung epithelial cells engages NF-κB at chromatin, transcriptional, protein and post-translational levels without engaging the type I interferon transcription factors, and loss of p65 or p50 abolishes viral replication in a manner rescued by reconstituting RelA transcriptional activity.
Isolating the SARS-CoV-2 Spike D614G substitution from the ORF1b P314L variant it travels with, through pseudotyped lentiviral particles and a trans-complementation assay with replication-competent virus, shows that the single Spike change raises entry efficiency across human lung, liver and colon cell lines without altering S1 affinity for ACE2.
A panel of eight human pluripotent stem cell derivatives spanning all three germ layers, together with adult primary islets and liver organoids, identifies pancreatic alpha and beta cells, hepatocytes, cholangiocytes, cardiomyocytes and dopaminergic neurons as permissive to SARS-CoV-2 and shows that permissiveness does not track ACE2 expression alone.
Across cell lines, primary bronchial epithelium, ferrets and patient material, SARS-CoV-2 infection produces a transcriptional response distinguishable from that to other respiratory viruses, combining low type I and type III interferon induction with a moderate interferon-stimulated gene response and strong chemokine and IL-6 expression.
A library of 135 barcoded coxsackievirus B3 clones shows that orally inoculated virus reaches systemic tissues within 20 minutes and replicates as a diverse population, after which fewer than three variants come to dominate every tissue in the animal without any detectable adaptive mutation.
A time-resolved phosphoproteomic survey of SARS-CoV-2-infected cells showing that infection acts mainly through signalling rather than protein abundance, activating casein kinase II and the p38 cascade while shutting down mitotic kinases, and converting that kinase profile into inhibitors with antiviral activity.
2019 · Cold Spring Harbor Perspectives in Medicine · lab-led
Frames influenza A virus as a compact genetic circuit whose modules can be disrupted, tagged or replaced, and organizes two decades of virus engineering into a design vocabulary of tracking, override, positioning and silencing modules that turns virus construction into a method of inquiry.
2019 · Proceedings of the National Academy of Sciences · lab-led
Forcing an interferon-stimulated gene program in human induced pluripotent stem cells with a constitutively active IRF7 produces lasting transcriptional change and impaired germ layer differentiation, supporting the proposal that the canonical type I interferon system and pluripotency are difficult to hold simultaneously.
A library of 107 barcoded influenza A viruses differing only in their NS1 sequence, competed in dog cells, human cells, chicken eggs and mice, resolves NS1-driven fitness as a set of divergent and partly convergent evolutionary trajectories rather than a single ordered adaptation gradient.
A survival-based genome-wide CRISPR knockout screen in human lung epithelial cells selected with an avian H5N1 isolate recovers sialic acid biosynthesis and transport as the dominant requirement for influenza entry, with the CMP-sialic acid transporter SLC35A1 as the top hit, and identifies the transcriptional repressor capicua as a negative regulator of cell-intrinsic immunity.
2018 · Proceedings of the National Academy of Sciences · lab-led
Applying one uniform small RNA-based selective pressure to four virus families in vertebrate cells shows that the ability to escape it tracks with the capacity for polymerase template switching rather than with genome polarity as such, since positive-strand viruses excise the targeted sequence while negative-strand viruses are cleared and a recombination-defective poliovirus cannot escape.
2018 · Proceedings of the National Academy of Sciences · lab-led
A one-step recombineering strategy that inserts hematopoietic-specific miR-142 target sites into the untranslated region of the human cytomegalovirus IE2 transcript permits virus rescue in fibroblasts while silencing IE2 selectively in myeloid cells, revealing that IE2 loss raises rather than abolishes replication in macrophages.
RNase III nucleases, including human Drosha and homologues from bacteria, archaea, yeast and a urochordate, restrict positive-strand RNA viruses by recognizing unbranched RNA stem loops and impairing the viral polymerase, separably from microRNA biogenesis, catalysis and interferon.
SARS-CoV generates three discrete small viral RNAs during infection of mouse lung, and blocking the one derived from the nucleocapsid gene with a locked nucleic acid antagomir reduces pulmonary inflammation, tissue damage and proinflammatory cytokine expression without measurably lowering lung virus titres.
A synthesis arguing that antiviral defenses across the three domains of life reuse a small set of designs, antisense recognition joined to nuclease activity and later to transcriptional and secreted responses, and proposing that chordates lost RNA interference through incompatibility with interferon.
Recreating a small RNA antiviral response in mice, using either host microRNAs repurposed as virus-specific guides or a virus-encoded artificial small interfering RNA, attenuates influenza A virus by more than five logs and prevents disease without any requirement for type I interferon signaling.
An attenuated influenza A virus engineered to deliver individual artificial small interfering RNAs enables a fitness-based loss-of-function screen inside an infected mouse, and that screen identifies MDA5 as a contributor to the antiviral response to influenza A virus despite the established role of RIG-I as the sensor that induces interferon beta.
Rapid vector-delivered destruction of the entire cellular microRNA population shows that post-transcriptional silencing makes no measurable contribution to the acute transcriptional response to double-stranded RNA or to type I interferon, while sustained loss of microRNAs derepresses a broad set of chemokines and proinflammatory cytokines in fibroblasts and in mouse lung.
Replication-incompetent influenza-based vectors carrying no DNA intermediate deliver coding messages and functional small RNAs together to primary human and mouse cells and to mouse lung, with output and cytotoxicity tuned by microRNA target sites in the nucleoprotein segment.
2014 · Proceedings of the National Academy of Sciences · lab-led
Loss of the nuclear RNase III enzyme Drosha, but not of Dicer, increases RNA virus replication in mammalian fibroblasts, and diverse RNA viruses drive Drosha into the cytoplasm by CRM1-dependent export in a manner that does not require new protein synthesis, RIG-I, TBK1 or type I interferon signaling.
Genetically barcoded influenza A virus libraries tracked through cell culture, embryonated eggs, guinea pigs, ferrets and mice show that transmission bottlenecks differ by route and recipient, with airborne transmission reducing a diverse inoculum to as few as two founder clones.
A Cre recombinase-expressing influenza A virus combined with Cre-responsive reporter and ablation mouse strains showed that a subpopulation of directly infected lung cells, predominantly club cells, survives productive infection, sustains elevated interferon-stimulated gene and chemokine expression, and contributes to bronchiolar epithelial damage after virus is cleared.
Sustained IRF7 activity induces the kinase MAP3K8, which phosphorylates the proline-rich hinge of IRF3 and redirects it from homodimers into IRF3 and IRF7 heterodimers, broadening the antiviral transcriptome and scaling the cellular response to the persistence of the viral threat.
Engineering vesicular stomatitis virus to eliminate RISC-loaded small RNAs attenuates rather than enhances replication in mice, and confers no replication advantage even when interferon signaling is removed, arguing that small RNA silencing does not contribute to mammalian antiviral defense.
Replication-competent Sindbis viruses, each encoding an artificial microRNA against one murine open reading frame, turn viral fitness in infected mice into a selection-based screen for host restriction factors, identifying the transcription factors Zfx and Mga as maintainers of antiviral capacity.
The inefficient 5 prime splice site of influenza A virus segment 8 functions as a timing device, causing the nuclear export protein to accumulate slowly as a minor product of abundant NS1 transcription, with both raising and lowering that rate attenuating the virus through mistimed ribonucleoprotein export.
A critical appraisal of the evidence for antiviral RNA interference in mammals, accepting that mouse embryonic stem cells generate virus-derived small interfering RNAs while finding the somatic cell case unproven, because the viral proteins invoked also antagonize interferon.
Engineering target sites for miR-192, a microRNA abundant in human and mouse respiratory tissue but absent from the ferret respiratory tract, into the influenza A virus hemagglutinin segment attenuates the virus in mice while leaving replication and transmission in ferrets intact, providing a genetic layer of biocontainment for transmission studies.
Argues that chordates, unlike plants, nematodes and arthropods, do not use small RNAs as antiviral defence, and that this absence of interplay between host microRNAs and RNA viruses is what leaves the microRNA machinery available for engineering viral tropism and small RNA delivery.
Influenza A virus small viral RNAs are shown to be synthesized from the complementary RNA intermediate, to load into the RNA binding cleft of the polymerase PA subunit, and to act there as segment-specific allosteric enhancers of full-length genome synthesis.
Poxviruses degrade host microRNAs through the catalytic subunit of their own poly(A) polymerase, VP55, which adds short nontemplated adenosine tails to argonaute-loaded guide strands and thereby marks them for cellular decay, while small RNAs carrying a 3 prime terminal 2 prime O-methyl group are spared.
Primary microRNA transcripts generated in the cytoplasm by a recombinant Sindbis virus are cleaved without any nuclear involvement yet still require Drosha, which relocalises from nucleus to cytoplasm on infection while the endogenous microRNA profile of the cell remains largely unchanged.
2012 · Proceedings of the National Academy of Sciences · lab-led
Influenza A virus engineered to be silenced by the hematopoietic microRNA miR-142 shows that replication inside antigen presenting cells is dispensable for CD8 T cell priming and clearance but required for much of the RIG-I-dependent type I interferon response in vivo.
A negative-sense cytoplasmic RNA virus, vesicular stomatitis virus, can be engineered to produce mature Dicer-dependent miR-124 that loads into Argonaute 2, silences targets, reaches many tissues in mice, and persists after the vector itself is cleared.
Inserting hematopoietic-specific miR-142 target sites into the dengue virus 3-prime untranslated region excludes replication from macrophages and dendritic cells in vivo and abolishes spread to other tissues, identifying hematopoietic cells as the dominant amplification compartment.
2011 · Proceedings of the National Academy of Sciences · co-led
Phosphorylation of STAT1 serine 708 by IKKε blocks formation of the STAT1 homodimer that constitutes GAF while leaving the STAT1 and STAT2 heterodimer of ISGF3 intact, biasing the shared STAT1 pool and the interferon-stimulated transcriptome toward the type I response.
2010 · Proceedings of the National Academy of Sciences · lab-led
Influenza A virus can be engineered to encode a cellular pri-microRNA inside an artificial intron of segment 8 and to produce mature, silencing-competent miR-124 during infection without measurable loss of replication or genome stability.
2010 · Proceedings of the National Academy of Sciences · lab-led
Influenza A virus produces a family of 22 to 27 nucleotide small viral RNAs corresponding to the 5 prime end of each genomic segment, which accumulate as the polymerase shifts toward genome synthesis and whose inhibition selectively depletes genomic RNA without comparably affecting messenger or complementary RNA.
Insertion of a primary microRNA locus into the exclusively cytoplasmic Sindbis virus genome yields mature, functional miR-124 through a Dicer-dependent but microprocessor- and Exportin-5-independent route, defining a cytoplasmic hairpin-processing activity in vertebrate cells that the authors term a virtron.
IRF7 and ISGF3 engage overlapping interferon-stimulated response elements and drive largely overlapping antiviral transcriptomes, so that a substantial interferon-like gene program is still induced when type I and type III interferon signaling are both absent.
Engineering microRNA response elements for a mammalian-ubiquitous microRNA directly into the influenza A virus nucleoprotein coding sequence attenuates the virus in mice while leaving growth in embryonated chicken eggs intact, yielding live attenuated vaccine candidates for H1N1 and H5N1.
Mice lacking IKKε produce normal interferon-β but fail to induce roughly a third of interferon-stimulated genes, because interferon activates IKKε, which phosphorylates STAT1 at Ser708 and thereby determines whether ISGF3 occupies a subset of response elements.
The IKK-related kinases IKKepsilon and TBK1 are identified as components of the virus-activated kinase activity that phosphorylates the C-terminal serine cluster of IRF-3 and IRF-7, linking pathogen sensing to type I interferon gene induction and to establishment of an antiviral state.