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

Abstract

To screen for cells with different sensitivities to interferon (IFN), NIH 3T3 mouse fibroblasts were subcloned and examined for their response to IFN treatment. Of 30 clones tested, 2 appeared to be relatively resistant to IFN, since the replication of both vesicular stomatitis virus and mengovirus was not inhibited, even in the presence of 1,000 U of IFN per ml. One resistant (A10) and one sensitive (A5) clone were further analyzed. In both clones, murine leukemia virus replication was equally inhibited by IFN, indicating the presence of functional receptors for IFN in the resistant clone. Using the (2'-5')oligoadenylate (2-5A) radiobinding assay, we could demonstrate that both clones contained the RNase L protein. Furthermore, this enzyme appears to be active, since a similar reduction in the rate of protein synthesis was evident after the introduction of exogenous 2-5A to the cells. We also analyzed the activity of another enzyme in the 2-5A pathway, namely, 2-5A synthetase. In the sensitive cells (AS), the induction of enzyme activity was proportional to the IFN concentration used, reaching a maximum of more than a 10-fold increase over the background of untreated cells. However, little if any induction over the basal activity was observed in the resistant cells (A10) when similar doses of IFN were used. It is thus probable that the lack of induction of 2-5A synthetase activity by IFN in A10 cells is at least partly responsible for their relative resistance to IFN treatment.

RETRACTED: Loss of (2'-5')oligoadenylate synthetase activity by production of antisense RNA results in lack of protection by interferon from viral infections.

“…This and other observations show that the small RNA antagonizes the antiviral activity of IFN by preventing activation of PKd, (15,16). Murine cell variants defective in the induction of 2-5A synthetase have been reported (17). IFN does not inhibit replication of vesicular stomatitis virus and mengovirus in these cells, but it is not known whether it induces the PKdS It is often difficult to establish whether cell variants are defective in the synthesis of a single IFN-induced protein.…”

Type I and Type II Interferons Inhibit the Translation of Murine Norovirus Proteins

“…MNV-1.CW1 displayed various degrees of sensitivity to rIFN-␤ pretreatment in other M cell lines (Fig. 1C), suggesting that certain murine M cell lines (i.e., IC-21) may be deficient in their ability to respond to IFN, a common phenomenon in immortalized cell lines (43). Type I IFN pretreatment also inhibited MNV-1 virion production in primary BMMs and BMDCs in a dose-dependent manner (Fig.…”

Viral Aspects of Protein Phosphorylation

“…Nilsen et al, 1982;Miyamoto et al, 1983 ;De Benedetti et al, 1985), whereas others favour the oligo(A) system (e.g. Salzberg et al, 1983;Jacobsen et al, 1983). It seems most likely that the type of both the interferon and the cell governs the relative contribution of these two inhibitory systems (Nilsen et al, 1982;Romeo et al, 1985;Kitajewski et al, 1986b).…”