TEMPERATURE-SENSITIVITY OF THE REPLICATION OF RABIES VIRUS (HEP-FLURY STRAIN) IN BHK-21-CELLS .1. ALTERATION OF VIRAL-RNA SYNTHESIS AT THE ELEVATED-TEMPERATURE

We investigated the nature of temperature sensitivity of the HEP strain of rabies virus. After initial incubation for appropriate period (more than 12 hr) at the permissive temperature (36-37°), incubation temperature of the rabies virus infected cultures was shifted to a nonpermissive temperature (39.5-40.5°). Upon the upshift, virion production was ceased, but the rate of viral RNA synthesis was greatly increased and reached almost 10 times that of 36°-infection within 8-10 hr, and then the activity quickly decreased together with the onset of accelerated CPE. Little or no 42S genome-sized RNA was produced at the elevated temperature, and almost all RNAs produced in large amounts seemed to be viral mRNAs and were shown to be functional in the cell-free translation system. Consistent with these observations, the viral ribonucleoprotein complex isolated from the temperature-upshifted culture was associated with relatively large amounts of small sized RNAs, which might reflect their increased transcriptive activity. These observations suggest that the viral RNA polymerase itself is not temperature-sensitive and the temperature-induced defect may reside in the regulatory factor which plays a role in turning on the synthesis of viral genome-sized RNA. © 1992.