Heterologous antibody responses of calves to Anaplasma centrale and A. marginale

Antigens of Anaplasma centrale, Onderstepoort isolate, and A. marginale, Wacol isolate, were analysed by a Western blotting technique. Sera from A. centrale-infected calves reacted to 41- and 38-kDa antigens in A. centrale and a 41-kDa antigen in A. marginale. Serum collected during the primary reaction from an A. marginale-infected calf reacted only to the 41-kDa antigen of A. marginale; heterologous antibody response to the 41-kDa antigen of A. centrale did occur later during the infection, but remained markedly weaker than the homologous response. The serologic cross-reactivity to this 41-kDa Anaplasma antigen confirms that it is common to the genus and also that it is a heterogeneous complex.