Activation of mosquito complement antiplasmodial response requires cellular immunity

infection was investigated by labeling this cell population in vivo. We found that midgut nitration triggers the local release of hemocyte-derived microvesicles (HdMv) into the basal labyrinth of the midgut. Several different strategies, such as gene silencing, immune priming, or systemic injection of polystyrene beads, were used to either enhance or reduce HdMv release. We provide direct experimental evidence that contact of hemocytes with the nitrated midgut basal surface triggers HdMv release and that this response is necessary for effective activation of mosquito complement. Our studies suggest that hemocyte-derived microvesicles may deliver some critical factor(s) that promote activation of thioester-containing protein 1, a key effector of the mosquito antiplasmodial immunity.