THE ROLE OF ANTI-VARIABLE SURFACE GLYCOPROTEIN ANTIBODY-RESPONSES IN BOVINE TRYPANOTOLERANCE

It has been reported that some breeds of cattle such as the N'Dama mou nt a more effective antibody response to the variable surface glycopro tein coat of trypanosomes and that this may contribute to their abilit y to control the infection. Thus we have investigated antibody respons es to surface exposed epitopes of the variable surface glycoprotein in Trypanosoma congolense-infected N'Dama (trypanotolerant) and Boran (s usceptible) cattle. Similar titres and isotypes were found in both N'D amas and Borans indicating that trypanotolerance is not associated wit h superior antibody-mediated destruction of trypanosomes. However, sig nificant differences in antibody responses to cryptic VSG epitopes and non-trypanosome antigens were identified. Trypanosusceptible Boran ca ttle had low IgG(1) responses to cryptic epitopes but high IgM respons es to non-trypanosome antigens such as beta-galactosidase. In contrast the N'Dama cattle had significantly higher IgG(1) responses to crypti c VSG epitopes and negligible responses to beta-galactosidase. These r esults indicate differences in the indiction of anti-trypanosome immun e responses between trypanotolerant and susceptible cattle infected wi th T. congolense.