Comparative study of virion transcriptase of some influenza virus strains

The activities, the temperature and pH optima of in vitro functioning and stability upon heating of virion transcriptase of 10 human influenza virus A strains differing in reactogenicity and isolated in different epidemiological situations, and of fowl plague virus (FVP) were compared. As compared with virion transcriptase of human influenza virus strains studied, that of FPV had a higher pH optimum, was capable of functioning in vitro at a higher temperature and was more stable on heating. Freshly isolated and vaccine influenza virus strains on the one hand and strains isolated at the peak and in the end of an epidemic did not differ in the virion transcriptase properties. The virion transcriptase of a strain isolated from a local influenza outbreak was much less active than transcriptase of a highly epiedmic strain.