Identification of antigenic differences that discriminate between cattle vaccinated with Anaplasma centrale and cattle naturally infected with Anaplasma marginale

Monoclonal antibodies were raised against the vaccine strain of Anaplasma c entrale used in Australia. A monoclonal antibody that reacted with an 80 kD a antigen was used to develop an A. centrale-specific fluorescent antibody test that will be useful for confirming species identity in patent infectio ns. Another monoclonal antibody that reacted with a 116 kDa antigen was use d to develop an A. centrale-specific competitive inhibition enzyme-linked i mmunosorbent assay (ELISA) for the serological identification of vaccinated cattle. The sensitivity of the ELISA was 100% in cattle experimentally inf ected with A. centrale, 97.1% in a vaccinated beef herd and 98.3% in a vacc inated dairy herd. The specificity of the ELISA was 98.6% in non-vaccinated cattle outside the Anaplasma marginale-endemic area, 97.9% in nonvaccinate d cattle within the A. marginale-endemic area and 100% in cattle experiment ally infected with A. marginale. The ELISA detected antibodies to A, centra le in cattle up to 9 years after Vaccination with no apparent decrease in s ensitivity. The assay has proved extremely valuable in Australia for invest igating reported failures of multivalent live vaccines used to protect catt le against anaplasmosis and babesiosis, and should be similarly useful else where in the world where these types of vaccines are used, e.g. Israel and South America. (C) 2001 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.