Elucidation of mosquito-malaria parasite interaction using genetically engineered mosquitoes

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Malaria sporozoites invade the mosquito salivary glands and wait in the salivary duct until the next blood feeding. The mechanisms of the process and molecules involved in the salivary gland invasion remain largely unknown. To establish a robust salivary gland-specific transgene expression in Anopheles stephensi, we obtained a salivary gland-specific promoter for a gene encoding Anopheles anti-platelet aggregation protein (AAPP). The aapp promoter is a female salivary gland-specific and blood meal-inducible strong promoter. Using this promoter, we generated a transgenic An.stephensi expressing abundant Discosoma sp. red fluorescent protein (DsRed) in the distal-lateral lobes of the glands, where the sporozoites invade preferentially. These results open up the possibilities of elucidating salivary gland-parasite interactions and generating transgenic mosquitoes refractory to parasites.Recent advances in the genetic engineering of anopheline mosquitoes have raised hopes for their use as … More new strategies for malaria control and provided a powerful tool to investigate mosquito-parasite interactions. Our research on transmission blockade using transgenic mosquitoes has been focused on the midgut stage of the parasites, interfering with ookinete invasion or oocyst differentiation. The molecule that we have introduced into a transgenic mosquito is CEL-III isolated from Cucumaria echinata (Marine invertebrate). CEL-III has strong hemolytic activity as well as haemaggrutination activity as a lectin. CEL-III gene expression was driven by the carboxypeptidase promoter, midgut specific promoter. As expected, CEL-III expression was induced in the midgut at 6h after a blood meal. We fed control and transgenic mosquitoes on the same infected rat and measure the numbers of oocysts formed. The transmission blocking efficacy of the transgenic mosquitoes was 91%, as compared with control mosquito. Thus, expression of CEL-III in the mosquito midgut severely reduced vector competency by inhibiting Plasmodium development. Because CEL-III targets to red blood cells but not the parasites, we anticipate that this CEL-III transgenic mosquito will be able to impair parasite development of all Plasmodium species. Less