CONDITIONAL LETHAL MUTANTS OF VESICULAR STOMATITIS-VIRUS .4. RNA SPECIES DETECTED IN NON-PERMISSIVE CELLS INFECTED WITH HOST-RESTRICTED MUTANTS

Host-restricted (hr) mutants of vesicular stomatitis virus were previously isolated and found to be defective for virus-specific RNA synthesis based on impaired uptake of RNA precursors by nonpermissive human cells [Simpson, R. W., and Obijeski, J. F. (1974). Virology 57, 357-368.]. This study has allowed a further classification of some of these mutants according to the RNA species detected by electrophoretic analysis of total cytoplasmic RNA extracted from infected, actinomycin-treated cells. In HeLa/M cells, the mutants examined produced either no detectable RNA or all expected size classes (12-18 S, 30 S, 42 S). However, the former type of mutant could be shown to initiate primary transcription in vivo. HeLa/Ohio cells were found to be substantially more permissive than HeLa/M or other human cells for growth of most hr mutants tested. The patterns of RNA synthesis observed with different hr mutants in HeLa/Ohio cells included no detectable species, deficiencies for 42 S RNA, or production of all expected size classes. As a biochemical correlate of complementation, enhanced RNA synthesis and viral replication could be demonstrated in HeLa/Ohio cells doubly infected with certain pairs of hr mutants. These data illustrate that the intracellular synthesis of virus-specific RNA species by VSV is controlled, in part, by cellular factors which are yet to be identified. © 1979.