Regulation of Salivary Output by Mosquitoes.

Abstract : A major scientific advance was registered during the present reporting period when discovered that the saliva of mosquitoes mainly functions during blood-feeding by preventing platelets from aggregating. Salivary-ablated mosquitoes probe extensively, but without feeding. The salivary enzyme mainly responsible for this antihemostatic effect was identified as an apyrase, which may partially be conserved during sugar-feeding, but selectively released when hosts are probed. Resynthesis, however, is rapid. Chemosensory factors regulate salivary secretion. Salivarian pathogens, such as malaria sporozoites, impair the ability of the salivary glands to secrete apyrase, thereby increasing the ability of infected mosquitoes to transmit the infection. In addition, we discovered that these salivarian pathogens require a dau or more to pass from the salivary acini to the lumen of the duct, and this suggests that the extrinsic incubation period of these organisms may be longer than previously thought. Taken together, these discoveries have greatly enhanced our understanding of the epidemiology or arboviral and other vector-borne infection.