Russell's viper toxoid: the influence of immunisation schedule and age of the toxoid on antibody response in immunised rabbits and monkeys

ABSTRACT

The influence of imrnunisation schedule and age of Russell's viper toxoid on antibody response in immunised rabbits and monkeys was studied. Rabbits were immunised subcutaneously with the toxoid at 0,4 and 8 weeks. For subsequent boosting at 6 wk intervals from 24 to 56 wks, fresh toxoid was used in one group (n=3) and the same batch of aged toxoid in another (n=3). lmmunisation of monkeys was carried out up to 40 wks using the latter schedule. Antibody levels peaked at 6-8 wks after the 3rd injection and fell to low level at 24 wks after the first injection. Subsequent boosting at 6 wk intervals from 24 wks onwards resulted in increase in antibody level reaching peak at 12 wk after the 1st booster injection and sustained at its peak throughout the course of immunisation. Antibody response observed in the monkeys was similar to that of the rabbits, however a lower level of antibody was observed. The patterns of antibody response observed following use of both toxoids were comparable. Feasibility and cost effectiveness of boosting at 6 wks intervals in prophylactic active immunisation of farmers at risk with Russell's viper toxoid need to be studied.