Adjuvant effect of bovine heat shock protein 70 on piroplasm surface protein, p33, of Theileria sergenti.

In this study, we investigated the immunological effects of bovine heat shock protein 70 (HSP70) on the major Theileria sergenti surface protein (p33). The gene encoding p33 was expressed as a fusion protein with bovine HSP70 from a plasmid vector. The adjuvant function of HSP70 on p33 was evaluated with regard to antibody response, cytokine production, and a challenge experiment in mice or cattle. HSP-p33 fusion protein provoked higher humoral and cellular immunity than either Escherichia coli-expressed p33 or piroplasm soluble protein. The HSP adjuvant activity toward p33 was also possible to detect in the inoculated cattle. The overall growth of parasites in cattle was significantly restrained in the HSP-p33-inoculated group, up to 50-52 days longer than in the controls. The present results indicate that HSP-p33 fusion protein is a promising candidate vaccine for clinical theileriosis in the field.