Degradation of Host MicroRNAs by Poxvirus Poly(A) Polymerase Reveals Terminal RNA Methylation as a Protective Antiviral Mechanism
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.