Effect of adjuvants on the humoral immune response to congopain in mice and cattle

Mice immunized with recombinant C2 in TiterMax？, Adjuphos？, purified saponin Quil A？ or Gerbu？ showed the best response according to the evaluation criteria and the latter three were chosen for the cattle vaccination study. The cattle were challenged with T. congolense four and a half months after the last booster. Cattle immunized with recombinant C2 in purified saponin Quil A？ showed the best antibody response according to the measured parameters.We identified purified saponin Quil A？ as a good adjuvant for immunizations with C2. The results from this study will be useful in future attempts to develop an effective anti-disease vaccine against African trypanosomosis.Trypanosomosis is a chronic wasting disease afflicting cattle and other livestock in sub-Saharan Africa and other parts of the world [1] and is caused by tsetse fly-transmitted protozoan parasites belonging to the genus Trypanosoma. Chemotherapy and chemoprophylaxis have not proved to be very effective against the disease due to two main reasons:- the prohibitively high cost of trypanocidal drugs to resource-poor farmers [2] and the development of drug resistance [3]. Efforts to develop a vaccine directed against the immunodominant variant surface glycoprotein (VSG) have not been successful due to antigenic variation [4]. Vaccination efforts have shifted towards the characterization of invariant antigens that are accessible to the specific antibodies such as glycerophosphate-inositol anchor [5], flagellar pocket (FP) fractions [6] and tubulin [7].An alternative approach based on an ‘anti-disease’ rather than an anti-parasite vaccine strategy was proposed following observations that trypanotolerant African taurine cattle, which have a natural ability to control trypanosome infection [8], develop more prominent antibody responses to congopain - the major cysteine protease (CP) of T. congolense than trypanosusceptible breeds [9]. It was hypothesized that congopain may therefore play a role in pathology of