Liaisons dangereuses: sexual recombination among pathogenic trypanosomes

Sexual recombination between pathogenic microbes has the potential to mobilise genes for harmful traits into new genetic backgrounds creating new pathogen strains. Since 1986 we have known that genetic exchange can occur in trypanosomes, but we are only now starting to unravel details of the process. In Trypanosoma brucei genetic exchange occurs in the tsetse vector, but is not an obligatory part of the life cycle. The process involves meiosis and production of haploid gametes, and thus appears to be true sexual reproduction. This review looks at the experimental evidence concerning genetic exchange and identifies current gaps in our knowledge.