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 in an exonuclease-dependent manner. May also play additional roles in the maturation of snRNAs and rRNAs, and in ribosome biogenesis (By similarity). 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 (By similarity). Induced by interferons alpha and beta. Weaker induction was seen with interferon gamma. Increased expression was seen at the transcriptional level (By similarity). Belongs to the exonuclease superfamily.