Authors
RC Bruce2; PM Hayes2; J Murphy2; W Gibson1; 1 University of Bristol, UK; 2 University of Westminster , UK Discussion
Tsetse flies (genera Glossina) are the sole biological vectors of African Trypanosoma species, the infectious agents of African Trypanosomiasis. Vector control is a key inhibitor of disease transmission; however, long-term control measures are economically and ecologically unsustainable and therefore, alternatives must be explored. Genetic interventions influenced by host-pathogen coevolution could present one such alternative. In this presentation, we explore the genetic variation and evolution within three immune genes Attacin-A (AttA), Defensin (Def) and Toll-like receptor 2 (TLR2) and the consequences for symbiont and parasitic interactions within a wild Glossina morsitans morsitans population.
Nucleotide variation within Def and AttA was found to be similar, exhibiting eight and eleven polymorphic sites respectively, while nucleotide variation within TLR2 was found to be considerably higher. A recent population expansion event and deviations from neutrality was also detected in all genes. Interestingly, genetic variation within AttA and TLR2 was found to be maintained via purifying selection, while Def exhibited signs of the Red Queen arms race and balancing section. Trypanosome infection rates were unexpectedly high (69.35%), consisting of mixed species infections, although samples exhibiting Def variants under positive selection were observed to reduce infection rates within samples. Furthermore, these initial results indicate a potential correlation between TLR2 variation and endosymbiont population variation.
The results within show that further research is required to fully understand the interactions and impacts of genetic variation on Trypanosoma infection rates within wild tsetse, however that an understanding of host-pathogen evolution and interactions of the could be used to inform novel genetic control methods. 
