A Mouse Cell Line, which Is Unprotected by Interferon against Lytic Virus Infection, Lacks Ribonuclease F Activity

Abstract

A mouse cell line, N I H 3T3, does not respond to some of the activities of interferon. Even after treatment with high concentrations of interferon the replication of lytic viruses, such as encephalomyocarditis virus (EMCV) and vesicular stomatitis virus (VSV) is not inhibited in these cells. In contrast, interferon treatment of these same cells results in the inhibition of Moloney murine leukemia virus (MMuLV) production. We have analyzed enzymatic pathways which are induced by interferon in these cells. After interferon treatment, the level of the (2'-5')oligoadenylate [(2'-5')A,] synthetase activity and the phosphorylation of the 67000-dalton protein (PI) are enhanced in NIH 3T3 cells to approximately the same level as interferon-sensitive mouse L-cells. Moreover, NIH 3T3 and L-cells contain approximately the same levels of enzymcs which inactivate (2'-5')A,. Both exogenously added (2'-5')Aj or double-stranded RNA (ds RNA) failed to inhibit protein synthesis in NIH 3T3 extracts even though they were potent inhibitors of L-cell extract-directed protein synthesis. Direct measurements of the (2'-S')A,-dependent ribonuclease F (RNase F) failed to detect such activity in NIH 3T3 cells. Our results, therefore, suggest that the presence of RNase F activity is necessary for the interferon-induced antiviral activity against EMCV and against VSV. The induction of protein kinase activity by interferon treatment of NIH 3T3 cells appears to have no direct effect on EMCV and VSV replication.

Inhibition by Interferon of Herpes Simplex Virus Thymidine Kinase and DNA Polymerase in Infected and Biochemically Transformed Cells

“…The inhibition of RNA viruses, such as EMC and reovirus, in IFN-treated cells has been shown to be dependent on a factor (dsRNA) provided by the replicating virus for the activation of the (2',5')oligoadenylate synthetaseRNase F pathway (Knight et al, 1980;Nilsen et al, 1982). It should be noted here that induction of these two enzyme pathways in the L-cells used in this work required relatively low concentrations of IFN (25 units/ml) (Epstein et al, 1981). These concentrations of IFN which inhibited EMC virus had no effect on HSV-1 replication.…”

“…The LTK + cell line was received from R. Stein and H. Cedar of the Hebrew University, Jerusalem. LB mouse cells have been previously described (Epstein et al, 1981). The HSV-I wild-type, NIH strain and HSV-I TK-mutants, derived from the NIH strain (Becker et al, 1982), were obtained from Y. Shtram and Y. Becker of the Hebrew University, Jerusalem.…”

Isolation and characterization of an interferon-resistant cell line deficient in the induction of (2'-5')oligoadenylate synthetase activity.

“…Several studies (7,20) suggest that the presence of RNase L activity is necessary for the development of the IFN-induced resistance against lytic RNA viruses. A10 cells appear to contain RNase L; moreover, the enzyme could be activated in the presence of exogenous 2-5A to inhibit protein synthesis in these cells.…”

“…A correlation between the biological effects of IFN and the induction of the 2-5A synthetase pathway has been suggested by some investigators (3,7,16,17); others (25) have claimed that such a correlation has not been established. One way of resolving this problem would be to isolate cell variants lacking the enzymes involved in the 2-5A system.…”

The Interferon-induced Hyporesponsive State in Variant and Parental L Cells: A Requirement for Cell Division

“…For example, while some lines are resistant to the antiviral effect and CGI by the type I IFNs, they remain sensitive to these cellular effects of type II IFN (DeMaeyer-Guignard et al, 1980b;Ankel et al, 1980). Another line selected for resistance to IFN has a high basal level of the enzymes induced by IFN but increased enzymic activities are not induced in this line by IFN (Verhaegen et al, 1980), A naturally occurring variant, which is resistant to the antiviral effect of IFN when challenged by encephalomyocarditis virus and resistant to CGI by IFN, remains sensitive to the antiviral effect when challenged by a murine leukaemia virus (Czamiecki et al, 1981;Epstein et al, 1981).…”