Antagonistic action of blood-feeding and mating on the gut immunity in the female mosquito Aedes aegypti

The female mosquito Aedes aegypti needs a blood meal to reproduce and is therefore a vector of arthropod borne viruses (arboviruses) such as Zika (ZIKV) or chikungunya (CHIKV) viruses. Even though mosquitoes transmit viruses, they possess different immune pathways to fight against pathogens. Surprisingly, the analysis of immune gene expression in different tissues from non blood fed (NBF) or blood fed (BF) females revealed that these genes were repressed in the digestive tract from 2 to 30 h following blood meal. As the digestive tract is the first barrier to be overcome by an arbovirus during the first few hours/days after blood meal, our findings could explain the high susceptibility of Ae. aegypti mosquitoes to arboviruses. To investigate this hypothesis, it is required to identify the mechanism by which gut immunodeficiency is triggered. We would then be able to inhibit it and analyse the impact on mosquito infection/transmission. In addition to the acquisition of a blood meal, the female must mate before laying fertilized eggs. Mating has been shown to cause changes in the female physiology and behaviour such as refractoriness to further mating in many insects but also, mating has been shown to influence immunity in Drosophila. We found that mating transiently antagonizes the immune gene repression in the digestive tract of BF females compared to virgin BF females. The mechanisms by which blood-feeding and mating modulate gut immunity are under investigation and will be presented during the conference.