A study on the development of a DIVA strategy for Haemorrhagic Septicaemia
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Date
2011
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GADVASU, Ludhiana
Abstract
The present study was undertaken on the development of a DIVA strategy for Haemorrhagic Septicaemia. Protein profiles of ultracentrifuged pellet and OMPs of P. multocida strain P52 revealed the presence of 14 protein bands in the range of 16 to 120 kDa molecular weight. Among these, 32 kDa appeared to be the dominant protein band followed by 26, 30 and 37 kDa protein bands. Additional 7 bands were observed in sonicated supernatant preparation of P. multocida P52. Immunoblotting revealed 32 kDa protein band to be the major immunogenic protein band on testing by sera from marker and conventional vaccinated as well as infected rabbits, mice and cattle. The immunogenic protein band patterns were found to be similar in all the fractions of antigens (sonicated supernatant, ultracentrifuged pellet and outer membrane proteins) on testing with sera from marker and conventional vaccinated and infected rabbits, mice and cattle. No unique bands could be recognized on testing by sera from marker vaccinated animals compared to those from conventional vaccinated and infected animals. However, protein bands of 58, 52 and 46 kDa in all the three antigenic fractions (sonicated supernatant, ultracentrifuged pellet and OMPs) of P. multocida P52 were not recognized by sera from marker and conventional vaccinated and infected rabbits, mice and cattle, hence these could be exploited as potential target haptens for developing a candidate marker vaccine as well as a DIVA assay. The antibody titres estimated by MAT and IHA in rabbits and mice indicated that marker vaccine induced an immuneresponse comparable to that of conventional vaccine. The levels of IFN-γ in plasma were significantly higher (P<0.05) in marker vaccinated than conventional vaccinated cattle on day 7 and day 14 but no such difference was observed between BCG and marker vaccinated cattle on day 7.