has role protective antigen role protective antigen Theileria parva protein P67 Oliver He protein Allen Xiang Protegen ID: 598; NCBI Protein GI: 4106806; NCBITaxon: 5875 Immunization with recombinant forms of a sporozoite surface antigen (r-p67), derived from either bacterial or insect cells, induces high levels of sporozoite neutralizing antibodies in cattle.In vivo immunization studies have shown that approximately 30% of immunized cattle are nonreactors to a needle LD70 sporozoite challenge, 40% experience a mild disease reaction from which they recover, and the remaining 30% suffer severe disease and are clinically indistinguishable from controls. Transient parasitosis and mild clinical reactions are also observed in challenge of cattle immunized by infection and treatment and such responses constitute immunity to ECF. Hence, p67 is able to routinely induce immunity at a level of about 70% [PubMed: 11193661].