[Damaging action of Venezuelan equine and Eastern equine encephalomyelitis viruses on the chromosome apparatus of mouse bone marrow cells].

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.