Spermatocyte chromosome alterations in mice inoculated with antirabies vaccine and tetanus toxoid separately and in combination

The genotoxic potential of antirabies vaccine (ARV) and tetanus toxoid (TT) inoculated separately and in combination was evaluated by spermatocyte chromosome analysis in mice. Adult males were vaccinated with a dose of 1 ml/kg ARV once daily for 7 days, or with a dose of 1 ml/kg TT once only, or with both (TT being administered along with the last dose of ARV). Spermatocytes were analyzed over 1-6 post-vaccination weeks for numerical and structural changes as well as for univalent formation. Controls were age matched non-vaccinated males. Significantly high incidences of structural aberrations from wk 4 onwards and at wk 6 following inoculation of ARV and TT, respectively, suggested susceptibility of stem cells to the vaccines. Combined vaccination (ARV plus TT) showed an additive effect. Occurrence of univalents involving autosomes as well as sex chromosomes was very common in all the vaccinated groups, the sex chromosomes being prevalently involved. Structural aberrations showed a positive correlation with time, while univalent formation showed a negative correlation. It appears that factors for clastogenicity and univalent formation are different for both the vaccines.