[Reproduction and interferogenic activity of togaviruses]

A comparative study of the correlation between reproduction and the interferon-inducing activity of viruses in chick embryo fibroblast cultures was carried out with members of different groups of togaviruses: alphavirus (Venezuelan equin encephalomyelitis viru, VEE) and flavivirus (Saint Louis encephalitis virus, SLE). The correspondence between cycles of accumulation of intracellular and extracellular viruses and the dynamics of interferon production the synthesis of which began early in the stage of exponential virus growth and correlated with the dynamics of their reproduction, was determined. Reproduction of the viruses was found to be directly dependent upon the multiplicity of infection; optimal infecting doses for the induction of the largest amounts of interferon were established. The calculations of the reproductive activity of VEE and SLE viruses showed their yield per one cell to be approximately 10,000 PFU and 1,000 LD50, respectively. Partial thermal inactivation of the viruses resulted in decreased yields of the infectious virus and interferon production. The regimen of thermal inactivation at which infectivity was lost completely, but the interferon-inducing capacity was retained probably due to residual synthesis of viral RNA was established for VEE virus. From the fact that the pattern of realization of genetic information is similar for both viruses, a similar mechanism of interferon synthesis induction is assumed.