Occurrence of haemoparasites in donkeys in Central Zone, Tanzania

Abstract

Theileriosis is a lymphoproliferative tick-borne disease of cattle and other wild ruminants, caused by infection with a protozoan, Theileria parva. The disease is prevalent in cattle throughout Central, East and southern Africa, where it threatens 50% of the cattle population. There are various control and treatments methods used against theileriosis; however, they all have limitations. The available live immunisation method, the Muguga cocktail, does not confer protection against all field strains, particularly buffalo-derived T. parva. Attempts to develop a subunit vaccine have been promising but these have shown limited efficacy due to antigenic and genetic diversity of T. parva strains in the field. Thus, there is a need to search for additional vaccine candidates. A related study has identified potential vaccine candidates using a genome-wide in silico approach. Consequently, the aim of this study was to genotype one of the identified antigens. TP04_0028 was selected for genotyping among candidate genes with high expression levels in the schizont stage of both cattle- and buffalo-derived T. parva isolates. Specific primers were designed and optimised for PCR amplification and sequencing. The comprehensive analysis of sequences from 17 cattle- and 17 buffalo-derived T. parva, from East and southern Africa, showed conservation in 12 (60%) of the 20 TP04_0028 predicted epitopes, in both parasite types, irrespective of geographical origin. Eighteen of the 20 predicted epitopes are conserved amongst different BoLA alleles and an area of 7 overlapping epitopes could be the starting point for initial experimental evaluation of the immunogenic properties of TP04_0028. Once the immunogenicity of these epitopes have been tested and the extent to provide protection from cattle- and buffalo-derived infections have been verified, they may be considered for vaccine development.