4 April 2007
A paper in the April edition of PNAS reports the creation of a mosquito strain that has been genetically modified to be resistant to malaria. Anopheles mosquitoes are the insect vector for the Plasmodium parasite that causes malaria, a disease that is a leading cause of ill-health and death in the developing world, primarily sub-Saharan Africa.
A potential strategy for controlling malaria is by targeting the insect vectors to break the pathogen life-cycle. Now a US research team reports that the mosquito strain that had been genetically modified to block infection by Plasmodium berghei (the rodent-specific strain of malaria parasite) have a fitness advantage [Marrelli MT et al. (2007)Proc Natl Acad Sci USA 104(13):5580-3]. The transgenic mosquitoes, which express a small gut protein that blocks infection by the malaria parasite, were found to survive for longer and lay more eggs than the normal mosquitoes when both groups were fed on infected blood; this effect was not apparent when uninfected blood was used.
Comment: This work was in a mouse model system; the major human-specific forms of both the Plasmodium parasite and the mosquito vector differ from the rodent versions, so the results are not directly applicable to humans, but represent a useful ‘proof-of-principle’ that genetic modification of an insect vector could potentially form part of a strategy to control infectious diseases such as malaria.