title: Evidence for a common protective antigenic determinant on sporozoites of several Theileria parva strains.
abstract: The antigenic relationship amongst sporozoites of several Theileria parva strans isolated from different parts of East Africa was investigated. It was found that antibodies to T. parva ( Muguga ) sporozoites neutralized the infectivity of homologous sporozoites as well as those of T. parva (Uganda), T. parva lawrencei , T. parva ( Kiambu 5), T. parva ( Kabete 1) and T. parva ( Marikebuni ). The results correlated with those obtained from an in vivo challenge, in that cattle immunized against T. parva ( Muguga ) were either solidly resistant or developed only a transient parasitosis when challenged with T. parva lawrencei or T. parva (Uganda). The immunity exhibited by these animals paralleled the level of anti-sporozoite antibodies, such that animas with high titres were completely protected whereas those with low levels developed transient parasitosis. Furthermore, monoclonal antibodies made against sporozoites of T. parva ( Muguga ) were also capable of neutralizing the infectivity of sporozoites of other strains. These results indicate that the outcome of cross-challenge may depend on the level and avidity of the anti-sporozoite antibodies at the time of challenge. In addition, these findings show that there is a common protective antigenic determinant on sporozoites of all the T. parva strains investigated in this study.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D016782:Apicomplexa / Q000276:immunology*; D002417:Cattle; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000032:analysis*; D007109:Immunity; D007114:Immunization; D051379:Mice; D008807:Mice, Inbred BALB C; D009500:Neutralization Tests; D013801:Theileriasis / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes