Towards genetic manipulation of wild mosquito populations to combat malaria: advances and challenges

Malaria kills millions of people every year, yet there has been little progress in controlling this disease. For transmission to occur, the malaria parasite has to complete a complex developmental cycle in the mosquito. The mosquito is therefore a potential weak link in malaria transmission, and generating mosquito populations that are refractory to the parasite is a potential means of controlling the disease. There has been considerable progress over the last decade towards developing the tools for creating a refractory mosquito. Accomplishments include germline transformation of several important mosquito vectors, the completed genomes of the mosquito Anopheles gambiae and the malaria parasite Plasmodium falciparum, and the identification of promoters and effector genes that confer resistance in the mosquito. These tools have provided researchers with the ability to engineer a refractory mosquito vector, but there are fundamental gaps in our knowledge of how to transfer this technology safely and effectively into field populations. This review considers strategies for interfering with Plasmodium development in the mosquito, together with issues related to the transfer of laboratory-acquired knowledge to the field, such as minimization of transgene fitness load to the mosquito, driving genes through populations, avoiding the selection of resistant strains, and how to produce and release populations of males only.