Gene conversion is a convergent strategy for pathogen antigenic variation.

Recent studies on three unrelated vector-borne pathogens, Anaplasma marginale, Borrelia hermsii and Trypanosoma brucei, illustrate the central importance of gene conversion as a mechanism for antigenic variation, which results in subsequent evasion of the immune response and persistence in the reservoir host. The combination of genome sequence data and in vivo studies tracking variant emergence not only provides insight into the genetic mechanisms for variant generation and hierarchy in variant expression but also highlights gaps in our knowledge regarding variant capacity and usage in vivo.