IMMUNOGENICITY OF OUTER-MEMBRANE PROTEIN OF PASTEURELLA-MULTOCIDA IN BUFFALO CALVES

Outer membrane protein (OMP) from Pasteurella multocida serotype B:2 w as extracted and characterized using SDS-PAGE. Ten major polypeptide b ands of MW 88 to 25 kDa were observed. Immunoblotting suggested that t he polypeptides of MW 44, 37 and 30 kDa were the major immunogens. Buf falo calves vaccinated with the OMP vaccine or a commercial haemorrhag ic septicaemia oil adjuvant vaccine developed highest mean log(10) ELI SA titres day 21 postvaccination (pv). Antibody titres detectable in t hese animals using an indirect haemagglutination assay were lower than the ELISA titres but the pattern of the antibody response was similar . A passive mouse protection assay revealed that the maximum protectio n against the challenge infection was conferred by the serum collected from both the groups on day 21 pv and 26 pv. Following challenge with virulent P. multocida cells, all the five OMP vaccinated animals surv ived whereas only 2 out of the 3 HS oil adjuvant vaccinated animals wi thstood the challenge. Results suggested that OMP was protective and c ould be used in vaccines against haemorrhagic septicaemia.