Notably, none of the signal cascades known to be involved in mosquito immune responses appeared to be activated during infection by the two microsporidian species in either Ae. aegypti or An. quadrimaculatus, including the Toll pathway46, broadly induced by diverse pathogens including Gram-positive bacteria, fungi, viruses and Plasmodium47, the JAK-STAT48 pathway that mediates response to dengue virus infection in Ae. aegypti or the IMD pathway that regulates antimicrobial immune responses in Drosophila49. Here, TLR4 is linked to infection.