How to succeed in parasitic life without sex? Asking Leishmania.

Eukaryotes use sexual recombination to achieve innovation and adaptation to a changing environment, a mechanism that is exceptional in Leishmania. It is postulated that asexual mechanisms contribute efficiently to parasite fitness and that sexual recombination would not be necessary for the production of a large repertoire of genotypes. The model discussed in this review used a major Leishmania glycoprotein, gp63, which is involved in host-parasite relationships. Mitotic recombination, which occurs between and within tandem repeats, amplifies genes and generates genotypic diversity. The resulting variation in the protein sequence is concentrated in surface domains, in regions spanning T-cell epitopes and B-cell epitopes and might allow immune escape.