AN IMMUNIZATION TRIAL WITH IN-VITRO PRODUCED BABESIA-BIGEMINA EXOANTIGENS

Bovine babesiosis, caused by Babesia bigemina, is an important tick-tr ansmitted haemoprotozoan disease in the tropics. This study evaluated the immunoprotective efficacy of in vitro produced B. bigemina exoanti gens in bovine calves. The calves inoculated with B. bigemina exoantig ens did not show any clinical, parasitological or hypersensitivity rea ctions after inoculation. They withstood challenge without showing any clinical symptoms except a transient thermal reaction. In contrast, t wo our of four control calves exhibited clinical symptoms of babesiosi s and one died. On challenge, there was a significant reduction in the haematological values of both groups. However, this was more pronounc ed in the control animals, Challenge resulted into a normocytic hypoch romic anaemia. The vaccinated animals revealed a significant rise in a ntibody titres after vaccination as well as after challenge as detecte d by a single dilution ELISA. The rise in antibody titres of control a nimals was only moderate. Inoculation of B. bigemina exoantigens induc ed a protective immune response in the vaccinated animals which could protect them from infected blood challenge.