[Variability of attenuated alphavirus strains in virion aggregate infection].

A natural process of infection with multiploid virions was stimulated and the genetic effects occurring in this infection were studied in experiments with homogeneous attenuated strain of Venezuelan equine encephalomyelitis virus producing the smallest plaques. The process of infection with multiploid virions was reproduced by infecting the cells with artificially obtained aggregates. Under these conditions, small- and large-plaque virus was produced which in some cases had a higher virulence than the parental strain. A possible mechanism of this phenomenon and its practical implications for the evaluation of the properties of attenuated alphavirus strains is discussed.