Immunogenic Response of Rabbits to Monovalent and Polyvalent Antisera of Mannhaemia haemolytica Biotype A

Abstract

This work was carried out in University of Surrey UK Department of Microbiology. In this study, the efficacy of monovalent and polyvalent vaccines made from Mannhaemia haemolytica antigens, were evaluated by measuring specific serum antibody titers produced against the bacteria in immunized rabbits. Eleven biotype A strains of Mannhaemia haemolytica were used for raising polyvalent antisera in rabbits. Monovalent antisera were produced against the strains A1, A2, A6, and A9. Different routes of inoculations were applied for injecting rabbits with multivaccine; separate strains in different sites subcutaneously, mixed strains in different sides subcutaneously, mixed strains at one site subcutaneously and mixed strains intravenously. Slide agglutination and indirect haemagglutination tests were used for detecting and measuring specific antibodies against the strains used. Antisera against polyvalent immunogens protected 83-100% of rabbits against A1, A7 and 50% of rabbits against A2 challenge while the lowest protection (16- 33%) was seen in serotype A6. The results showed that the indirect haemagglutination test was more sensitive than the somatic agglutination tests and intravenous injection produced higher antibodiesresponses when compared to others routes of injection.

Keywords: Mannhaemia, rabbits, immunization, indirect haemagglutination, immunization.