CONDITIONAL LETHAL MUTANTS OF AN RNA ANIMAL VIRUS.
D004668:Encephalitis Viruses; D009154:Mutation; D012313:RNA; D012328:RNA Viruses; D012367:RNA, Viral; D012106:Research; D046509:Tissue Culture Techniques; D014776:Virus Cultivation
D012367:RNA, Viral; D012313:RNA
ENCEPHALITIS VIRUSES; EXPERIMENTAL LAB STUDY; MUTATION; RNA, VIRAL; TISSUE CULTURE; VIRUS CULTIVATION