Immunology of Insect Vectors: Midgut Interactions of Sandflies and Tsetse with Kinetoplastid Parasites as a Paradigm for Establishing Infection
Sloan MA., Ligoxygakis P.
© 2017 Elsevier Ltd For the vast majority of vector borne parasites the ability to overcome the insect midgut defences is central to transmission. However, for many such diseases we know virtually nothing about the molecular mechanisms involved. For vectors such as tsetse flies and sandflies the prospects for rapidly improving our understanding of key interactions occurring in the midgut when challenged by parasites are difficult. This is because the ‘tool box’ required untangling the interactions is very unlikely to be rapidly developed. For example, there is no realistic prospect of producing transgenic technology for tsetse flies because eggs are inaccessible due to intrauterine development of larvae; maintenance of multiple lines of either sand or tsetse flies permitting genetic studies is impossible because of the cost and complexity of culturing colonies; bioinformatics resources are still in their infancy. Nevertheless, through a combination of genomics, transcriptomics, RNAi experiments and work on endosymbionts, researchers in these difficult systems have placed the general framework of parasite establishment in the midgut. Here, we will review the major immune pathways by which tsetse and sandflies respond to kinetoplastid challenge in the midgut and the role of endosymbionts as well as the gut microflora in determining vectorial capacity.