Studies on the role of the 2'-5'-oligoadenylate synthetase-RNase L pathway in beta interferon-mediated inhibition of encephalomyocarditis virus replication

Abstract

Interferons inhibit the replication of vesicular stomatitis virus (VSV), but not of encephalomyocarditis virus (EMCV), in mouse JLSV-11 cells. We report the isolation of clonal derivatives from this cell line in which the replication of both viruses is impaired by interferons. These clones were selected from the parental line by virtue of their rescue by interferon treatment from the cytopathic effects of EMCV infection. In one such clone, RK8, the replication of VSV and EMCV and the production of resident murine leukemia virus were inhibited by interferon. On the other hand, in clone RK6, which was isolated without any selection, the replication of VSV, but not of EMCV, was impaired by interferons. The levels of 2'-5'-oligoadenylate synthetase mRNA and enzyme activity were similarly elevated upon interferon treatment in the two clones. However, the level of RNase L, as determined by binding and cross-linking of a radiolabeled 2'-5'-oligoadenylate derivative, was much lower in RK6 cells than in RK8 cells. In accord with this observation, the introduction of 2'-5'oligoadenylates into cells inhibited protein synthesis much less strongly in RK6 cells than in RK8 cells. These results are consistent with the notion that the 2'-5'-oligoadenylate-dependent RNase L may be a mediator of the inhibition of EMCV replication by interferons.

RNase L Mediates the Antiviral Effect of Interferon through a Selective Reduction in Viral RNA during Encephalomyocarditis Virus Infection

“…LS1 cells did not extend the range of viruses sensitive to 2-5A pathway antiviral activity to include VSV, confirming previous studies which demonstrated that multiple mechanisms are responsible for the full range of IFN's antiviral effects (31,36).…”

“…Introduction of 2-5A into cells has been shown to reduce the cytopathic effects of several viruses, including vesicular stomatitis virus (VSV), EMCV, poliovirus, and Semliki Forest virus (1), whereas a 2-5A analog inhibitor of RNase L has reduced the anti-EMCV activity of IFN in intact cells (51). Further, in cell lines in which 2-5A pathway activity is defective, EMCV replication is resistant to the inhibitory effects of IFN (31). The cloning of cDNAs encoding 2-5A synthetase (35,43) and RNase L (56) has provided a means of definitively addressing the antiviral function of the 2-5A system in cells.…”

Replication of lymphocytic choriomeningitis virus is restricted in terminally differentiated neurons

“…In addition, 2-5A-dependent RNase levels have been reported to be elevated during cell differentiation (33). Because several investigations have implicated the 2-5A system in the mechanism by which interferon inhibits the replication of picornaviruses (9,35,56), it is conceivable that the 2-5A system contributes to the restricted LCMV replication in NGF-treated PC12 cells. Nonetheless, after exposure to gamma interferon (100 U/ml for 24 h), BHK-21 cells had levels of 2-5A synthetase higher than that found in NGF-treated PC12 cells but only a very modest (5to 10-fold) concomitant decrease in LCMV production (data not shown), suggesting that it is very unlikely the 2-5A system is responsible for the 1,000-fold reduction in LCMV yield found in NGF-treated PC12 cells.…”

Wanderings in Biochemistry

“…Slattery et al (45) established that removal of 2-5A from RNase L restored its latency. The 2-5A RNase L system is a mediator of the inhibition of encephalomyocarditis virus replication by IFN (54).…”