Antigenic Variation and its Significance to Babesia

This chapter describes the mechanisms by which Babesia bigemina and Babesia bovis accomplish antigenic variations, and the way it may contribute to parasite survival. Agents of Texas redwater fever, Babesia bigemina, and Babesia bovis (. B.bovis), were the first protozoal parasites for which transmission by an arthropod vector was established. It was shown that once infected with B.bovis, animals uniformly remain infected for long periods. This behavior of establishing persistent infections is very common among babesial parasites. Although all "tricks" used by these parasites for causing infections are unknown, it is known that antigenic variation occurs in at least two species of babesial parasites, Babesia rodhaini and B. bovis. Considering that many babesial parasites establish persistent infections of long duration, there must be many undiscovered examples of antigenic variation in this genus, other than B. bovis and B. rodhaini. In addition, it is known that other distinctly different mechanisms of immune evasion may also come into play by this genus.