Trypanosoma vivax GM6 Antigen: A Candidate Antigen for Diagnosis of African Animal Trypanosomosis in Cattle

Background: Diagnosis of African animal trypanosomosis is vital to controlling this severe disease which hampers development across 10 million km2 of Africa endemic to tsetse flies. Diagnosis at the point of treatment is currently dependent on parasite detection which is unreliable, and on clinical signs, which are common to several other prevalent bovine diseases. Methodology/Principle Findings: the repeat sequence of the GM6 antigen of Trypanosoma vivax (TvGM6), a flagellar-associated protein, was analysed from several isolates of T. vivax and found to be almost identical despite the fact that T. vivax is known to have high genetic variation. The TvGM6 repeat was recombinantly expressed in E. coli and purified. An indirect ELISA for bovine sera based on this antigen was developed. The TvGM6 indirect ELISA had a sensitivity of 91.4 % (95 % CI: 91.3 to 91.6) in the period following 10 days post experimental infection with T. vivax, which decreased ten-fold to 9.1 % (95 % CI: 7.3 to 10.9) one month post treatment. With field sera from cattl