Immunological response of rabbits to Toxocara canis infection.

Abstract

Studies on immunological response of rabbits toToxocara canisinfection have been reported. It was observed that rabbits previously infected by two sublethal doses of 1200 infective ova each, with a 14-day interval between the two doses, acquired strong immunity to the effects of reinfestation induced by a large dose of infective ova, i.e. 100000. Post-mortem studies indicate that immunity is mainly directed against the migration of larvae to the lungs. The animals which resisted the effects of reinfestation showed an enhanced antibody response as shown by complement-fixation and agar-diffusion precipitin tests.The precipitin reaction in the sera of animals infected by oral and subcutaneous routes respectively was studied with three preparations of antigen, namely, saline extracts, boiled saline extracts of adult worms, and saline extracts of infective ova. It was observed that the extract of adult worms was deficient in a minimum of three antigenic components present in the extract of infective ova.It is a pleasure to thank Professor C. A. McGaughey for the facilities given for this study, Professor P. Seneviratna for his constructive criticism, and Messrs W. G. Senaratne and K. G. Karunaratne for technical assistance and the photo graphy respectively.