TEMPERATURE-SENSITIVE MOUSE-CELL FACTORS FOR STRAND-SPECIFIC INITIATION OF POLIOVIRUS RNA-SYNTHESIS

Two cell lines, TgSVA and TgSVB, were established from the kidneys of transgenic mice carrying the human gene encoding poliovirus receptor. The cells were highly susceptible to poliovirus infection, and a large amount of infectious particles was produced in the infected cells at 37-degrees-C. However, the virus yield was greatly reduced at 40-degre es-C. This phenomenon was common to all mouse cells tested. To identif y the temperature-sensitive step(s) of the virus infection cycle, diff erent steps of the infection cycle were examined for temperature sensi tivity. The results strongly suggested that the growth restriction obs erved at 40-degrees-C was due to reduced efficiency of the initiation process of virus-specific RNA synthesis. Furthermore, this restriction appeared to occur only on the synthesis of positive-strand RNA. Vims- specific RNA synthesis in crude replication complexes was not affected by the nonpermissive temperature of 40-degrees-C. In vitro uridylylat ion of VPg seemed to be temperature sensitive only after prolonged inc ubation at 40-degrees-C. These results indicate that a specific host f actor(s) is involved in the efficient initiation process of positive-s trand RNA synthesis of poliovirus and that the host factor(s) is tempe rature sensitive in TgSVA and TgSVB cells.