Antigenic variation by protozoan parasites: insights from Babesia bovis

Antigenic variation of surface membrane proteins by protozoan parasites enables these pathogenic organisms to avoid host immune responses and thus perpetuate long‐term infections. Babesia bovis, the causative agent of severe babesiosis in cattle, was previously shown to undergo antigenic variation through modifications to its primary surface antigen, a protein called VESA1. In this issue, Al‐Khedery and Allred provide a detailed description of the genes that encode VESA1 and present convincing evidence for progressive, segmental gene conversion in the generation of variant forms of this surface antigen.