Interrupting malaria transmission by genetic manipulation of anopheline mosquitoes.

Malaria ranks among the deadliest infectious diseases that kills more than one million persons every year. The mosquito is an obligatory vector for malaria transmission. In the mosquito, Plasmodium undergoes a complex series of developmental events that includes transformation into several distinct morphological forms and the crossing of two different epithelia--midgut and salivary gland. Circumstantial evidence suggests that crossing of the epithelia requires specific interactions between Plasmodium and epithelial surface molecules. By use of a phage display library we have identified a small peptide-SM1--that binds to the surfaces of the mosquito midgut and salivary glands. Transgenic Anopheles stephensi mosquitoes expressing a SM1 tetramer from a blood-inducible and gut-specific promoter are substantially impaired in their ability to sustain parasite development and transmission. A second effector gene, phospholipase A2, also impairs parasite transmission in transgenic mosquitoes. These findings have important implications for the development of new strategies for malaria control.