EVIDENCE FOR A COMMON PROTECTIVE ANTIGENIC DETERMINANT ON SPOROZOITES OF SEVERAL THEILERIA-PARVA STRAINS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 52  (2) , 231-238
Abstract
The antigenic relationship amongst sporozoites of several T. parva strains isolated from different parts of East Africa was investigated. 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 antisporozoite antibodies, such that animals with high titers were completely protected whereas those with low levels developed transient parasitosis. Monoclonal antibodies made against sporozoites of T. parva (Muguga) were also capable of neutralizing the infectivity of sporozoites of other strains. The outcome of cross-challenge may depend on the level and avidity of the antisporozoite antibodies at the time of challenge. Apparently, there is a common protective antigenic determinant on sporozoites of all the T. parva strains investigated in this study.