Establishment of robust salivary gland-specific expression in transgenic anopheline mosquito

Recent advances in the genetically engineering of Anopheline mosquitoes have raised hopes for their use as new strategies for malaria control and provided a powerful tool to investigate parasite-mosquito interactions. The interruption of the parasite cycle in the mosquito using transgenic strategies can occur at the midgut level, interfering with ookinete invasion or oocyst differentiation, and at the salivary gland level, blocking invasion of gland cells or the transmission of infective sporozoites from the salivary glands. So far, only the carboxypeptidase and vitellogenine promoters have been used for driving transgenes in mosquitoes for the gut- and fat body- specific expression, respectively. Therefore, research on transmission blockade using transgenic mosquitoes has been limited to the midgut stage of the parasites.

In the seminar, Shigeto Yoshida will present the development of transgenic Anopheles stephensi mosquitoes that specifically express Discosoma sp. red fluorescent protein (DsRed) in their salivary glands. Using advanced 3D confocal microscopy, robust expression of DsRed in the distal-lateral lobes of the salivary glands is observed, where the sporozoites invade preferentially, driven by a newly isolated salivary gland-specific promoter in a living mosquito as well as in dissected salivary glands. Furthermore, by using GFP-expressing sporozoites, Shigeto Yoshida will also show the parasites passing through the salivary glands from the outer surface. These results open up the possibility of elucidating the process and molecules involved in the salivary glands-parasites interactions, and may lead to the development of transmission-blocking strategies by using genetically modified mosquitoes that express anti-parasitic genes in a salivary gland-specific manner.