Antigenic variation in Trypanosoma evansi: a comparison of the predominant variable antigen type repertoire of stocks from Sudan.

The predominant VAT repertoire of 15 stocks of T. evansi from Sudan was characterised using 30 predominant VATs isolated from six of the stocks. The 15 stocks were grouped into three distinct serodemes, each member of a serodeme being associated by the presence of 6-7 particular VATs as part of their predominant VAT repertoire. Two VATs were part of the predominant VAT repertoire of all 15 stocks and were considered to represent isoVATs of T. evansi. The limited antigenic diversity found among these stocks of T. evansi compared with that found in other salivarian trypanosome species suggests that host immunity might have an important role to play in the natural regulation of T. evansi infection of livestock. Furthermore, control regimes based on immunoprophylactic methods may be more of a practical possibility in the case of T. evansi infections than in the case of other trypanosome species infecting livestock.