Mode of replication and temperature characteristics of the RNA polymerase of an influenza virus in vitro.

RNA-polymerase (RNA-dependent), influenza virus, double-stranded RNA While the enzyme template complex of fowl plague virus (FPV) polymerase is rather stable during incubation in v itro , some of the newly synthesized RNA is degraded rapidly. At low temperatures a pronounced lag phase of RNA synthesis occurs, which can be prevented by incu­ bation with substrate. The in vitro products are initially single-stranded RNA, which are con­ verted to partially double-stranded molecules by phenol and SDS. The results are compatible with an open replicative intermediate structure, in which the newly synthesized RNA is bound to the complementary template only over a rather short region at the growing point. A comparison of the temperature characteristics of the RNA polymerases of the highly virulent FPV with that of the low pathogenic virus N revealed that the lag phase is a virusspecific property. There appears to exist a correlation between virulence and heat stability of this enzyme, the activity of which is rate limiting at the normal temperature of the host (41 °C).