Temperature-sensitive virion transcriptase activity in mutants of WSN influenza virus.

Temperature-sensitive mutants of WSN influenza virus (10, 11, 12) were tested in vitro for activity of the virion RNA-dependent RNA transcriptase at various temperatures. Temperature-sensitivity was found for virion transcriptase activity of mutants belonging to complementation/recombination group I, but not groups II, IV and V. It was not possible on the basis of the results to specify the precise biochemical lesion of mutants from group III.