Inducible expression of the 2-5A synthetase/RNase L system results in inhibition of vaccinia virus replication.
Studies of interferon (IFN)-treated virus-infected animal cells have revealed the 2-5A system (2-5A synthetase/RNase L enzymes) as being responsible for virus inhibition only in the case of picornaviridae. To investigate whether those IFN-induced enzymes could be responsible for inhibition of poxvirus replication, we have generated recombinant vaccinia viruses (VV) containing the corresponding genes (VV-2-5AS and VV-RL, respectively). RNase L produced in cells infected with VV-RL leads to rRNA degradation and inhibition of virus protein synthesis, which correlates with about 92% reduction in virus yields by 48 hr after infection. Combined expression of this enzyme with 2-5A-synthetase further inhibits virus yields. The pattern of rRNA fragments produced by infection with viruses VV-RL and/or VV-2-5AS is the characteristic for activation of the 2-5A pathway by IFN treatment. Combined infection of VV-RL together with vesicular stomatitis virus (VSV) demonstrates this inhibition to be specific for VV and not due to a general effect. Breakdown of rRNA is largely due to the recombinant vector-derived enzyme, since a C-terminal deletion mutant of RNase L is inactive and the extent of rRNA degradation induced by infection with VV-RL is similar in cells treated or not with IFN. Moreover, the anti-VV effects of RNase L is also observed in a cell line lacking the endogenous ds RNA-dependent protein kinase (PKR). Thus, our findings provide direct evidence for antiviral activity of the 2-5A system on poxviruses.
Díaz-Guerra
M
M
CSIC, Campus Universidad Autónoma, Madrid, 28049, Spain.
Rivas
C
C
Esteban
M
M
D015088:2',5'-Oligoadenylate Synthetase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000998:Antiviral Agents / Q000096:biosynthesis / Q000378:metabolism; D002460:Cell Line; D004722:Endoribonucleases / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D004790:Enzyme Induction; D004926:Escherichia coli; D006801:Humans; D007372:Interferons / Q000494:pharmacology; D051379:Mice; D011817:Rabbits; D011995:Recombination, Genetic; D014616:Vaccinia virus / Q000235:genetics / Q000502:physiology*; D014779:Virus Replication
D000998:Antiviral Agents; D007372:Interferons; D015088:2',5'-Oligoadenylate Synthetase; D004722:Endoribonucleases; C031956:2-5A-dependent ribonuclease