[Effect of viral vaccines on animal bone marrow cell chromosomes]

A comparative study on the effect of a number of viral vaccines (live and inactivated vaccinia, poliovirus type II, measles, rabies vaccines) on chromosomes of mouse bone marrow cells was carried out. Most vaccines were found to impair the process of first divisions of these cells after vaccination. Live vaccinia vaccine and live fixed rabies virus cause an increase in the rate of structural chromosome aberrations at later intervals, 30-90 days after immunization. The main type of chromosome disorders is chromatid break. Some of the live vaccines studied (poliovaccine type II, measles vaccine) and inactivated vaccines caused no increase in the rate of cromosome structure disorders as compared to the control. Live fixed rabies virus exerts a stronger impairing effect on division of mouse bone marrow cells than a rabies vaccine with residual virulence. A rabies vaccine completely inactivated by UV-irradiation had no impairing effect on chromosomes of immunized animals. Thus, some live vaccines, unlike inactivated ones, cause chromosome disorders in bone marrow cells of mice late after immunization and, apparently, subsequent death of some cells with the most important distrubances.