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This study sought to identify antigens involved in protective immune responses to Cowdria by Western blotting using immune sera and surface labelling of elementary body (EB) proteins using biotin to identify which of these are outer membrane proteins. Antigens which could be considered as potential vaccine candidates were identified. Immunisation of goats with live Cowdria or with inactivated elementary bodies (IEBs) leads to development of antibodies to at least six antigenic components of the EB of 24kDa, 27kDa, 31kDa, 58kDa and 66kDa. In contrast immunisation of goats with detergent extracted soluble antigens stimulated production of antibodies to only four antigens of 24kDa, 27kDa, 28kDa and 31kDa. Six surface exposed antigens of the Cowdria elementary body were identified by biotin labelling, with molecular masses of 21kDa, 28kDa, 31kDa, 62kDa, 74kDa and 115kDa and are therefore considered outer membrane proteins. These proteins reacted with antibodies in sera raised by immunisation of goats with live or inactivated EBs. The 58kDa heat shock protein (GroEL) of C. ruminantium is an immunodominant antigen. The immune responses to 58kDa antigen expressed as a recombinant in E. coli were investigated by immunisation of mice and sheep. The immunised animals stimulated specific antibody which reacted with the native homologue on the EB 58kDa. Immunisation with recombinant 58kDa heat shock protein of C. ruminantium led to development a of specific antibody response of the IgG1 isotype. Challenge of immunised sheep showed a highly significant reduction (p |
