Interferon-induced antiviral exoribonuclease that acts on single-stranded RNA and also has minor activity towards single-stranded DNA. Exhibits antiviral activity against RNA viruses including hepatitis C virus (HCV), hepatitis A virus (HAV) and yellow fever virus (YFV) in an exonuclease-dependent manner. May also play additional roles in the maturation of snRNAs and rRNAs, and in ribosome biogenesis. Exonucleolytic cleavage in the 3'- to 5'-direction to yield nucleoside 5'-phosphates. Binds 2 manganese ions per subunit. Optimum pH is 7.0. Associates with PML and SP100 in the PML NB complex. Associates with survival motor neuron protein (SMN)-containing macromolecular nuclear complexes and U1 and U2 snRNAs and U3 snoRNA. Highly expressed in peripheral blood leukocytes, spleen, thymus, colon and lung. Up regulated by E2 in estrogen receptor-positive breast cancer lines. Induced by interferons alpha and beta. Weaker induction was seen with interferon gamma. Increased expression was seen at the transcriptional level. Belongs to the exonuclease superfamily.