[Damaging action of Venezuelan equine and Eastern equine encephalomyelitis viruses on the chromosome apparatus of mouse bone marrow cells]. / Povrezhdaiushchee deistvie virusov venesuél'skogo i vostochnogo éntsefalomielitov loshadei na khromosomnyi apparat kletok kostnogo mozga myshi.

Cytogenetical study of bone marrow cells of mice infected with pathogenic and attenuated strains of Venezuelan (VEE) and Eastern (EEE) equine encephalomyelitis viruses was carried out to elucidate the pattern of changes of the chromosomal apparatus in the infected animals, and differences in the effect of strains with different degree of pathogenicity on the cell during mitosis. It was shown that inoculation of mice with pathogenic and attenuated VEE and EEE virus strains led to the appearance in the bone marrow of a larger number of aberrant cells. Both VEE virus strain induced a significant increase both of the total number of aberrant cells and of the cells with true aberrations. The pathogenic and attenuated EEE virus strains also caused a marked increase in the number of aberrant cells, but while the number of true aberrant cells is significant for the pathogenic strain, the attenuated strain causes an insignificant change in this parameter.

[Effect of virulent and anttenuated variants of viruses of American equine encephalomyelitis on the mitotic activity of the cells]. / Vliianie virulentynykh i attenuirovannykh variantov virusov Amerikanskogo entsefalomielita loshadei na mitoticheskii rezhim kletok.

A comparative study of reproduction of Venezuelan and Eastern equine encephalomyelitis (VEE and EEE) viruses in L cell culture showed the disorders of the mitotic activity of the infected cultures to depend on the variant of the inoculated virus and the degree of its attenuation. The highest number of pathological mitosis was observed within 12--24 hours after inoculation of the cultures, the attenuated variants of both the viruses causing lower numbers of pathological mitoses than virulent variants. EEE virus was found to induce accumulation of pyknotized nuclei in the stage of telophase in the culture.