Studies on interferon-sensitive cells derived from the interferon-resistant NIH 3T3 clone 1 line

From the NIH 3T3 clone 1 line which is normally unprotected by interferon (IFN) against lytic virus infection we have selected subclones which show high sensitivity to IFN. The selection procedure was based on encephalomyocarditis virus (EMCV) as selection agent. In the IFN-sensitive subclones thus obtained EMCV replication was inhibited by IFN to a similar degree as observed in L929 cells. Like in the original NIH 3T3 clone 1 line, however, replication of vesicular stomatitis virus (VSV) and cell multiplication were only marginally affected by IFN. We measured the levels of known IFN-induced enzymes (2-5A-synthetase, dsRNA protein kinase and 2-5A-dependent RNase) in a number of subclones and found no consistent differences to the original population. Thus, the newly acquired IFN-dependent protection against EMCV may be mediated by a different antiviral mechanism.