Inactivated Trivalent Vaccine for Leptospira in Andhra Pradesh

Leptopsirosis, the world wide zoonosis is considered as re-emerging disease. Besides economic losses caused by Leptopsira to animal production, its zoonotic character makes it an important public health problem Seroepidemiological studies conducted using MAT indicated the dominance of L. hardjo, L. grripotyposa and L. autumnalis in the state. Hence, serovars hardjo, grripotyposa and autumnalis were selected as vaccine candidates for the preparation of trivalent vaccine. The homology and purity of the vaccine candidates were checked using reference antisera procured from ICMR, Port Blair, Center for Diagnosis and typing of leptospira, Andaman and Nicobar Islands and also using hyper immune sera raised against the respective serovars in the present study. The candidate vaccine strains were adopted to low protein medium containing 0.2 percent Bovine serum albumin (BSA) and adjusted the concentration to 2x109 cells/ml. The leptospiral organisms were inactivated with 0.5 percent formalin and adjuvanted with aluminum hydroxide (vaccine-I and Montanide (vaccine-II). The vaccines prepared were evaluated for sterility, safety and potency tests. The immune responses were studied in rabbits using both the types of adjuvanted vaccines and could not find any significant differences between the vaccines. The immune response was found to be satisfactory with both the types of vaccines up to 150 days of post vaccinated period tested. The present work has been carried out during 2006 to 2010.