Evaluation of recombinant sporozoite antigen SPAG‐1 as a vaccine candidate against Theileria annulata by the use of different delivery systems

Summary The major sporozoite surface antigen of Theileria annulata (SPAG‐1) is a candidate for inclusion in a subunit vaccine. In this paper we summarize the results of 4 vaccination experiments using recombinant SPAG‐1 expressed in different systems and presented in different adjuvants. The antigen has been presented as either a C terminal 108 amino acid peptide (called SR1) expressed as both β‐galactosidase and hepatitis B core antigen fusions or as a full‐length form expressed as a GST fusion with an N terminal His6 tag. We used different adjuvants, namely Freund's, saponin, ISCOMs and a proprietary adjuvant supplied by SmithKline Beecham, which we call SKBA. The data point to the conclusion that SPAG‐1 can elicit partial protection and is therefore suitable for inclusion in an eventual multicomponent subunit vaccine.