Using bacteria to express and display anti-Plasmodium molecules in the mosquito midgut

Bacteria capable of colonizing mosquito midguts are attractive vehicles for delivering anti-malaria molecules. We genetically engineered Escherichia coli to display two anti-Plasmodium effector molecules, SM1 and phospholipase-A(2), on their outer membrane. Both molecules significantly inhibited Plasmodium berghei development when engineered bacteria were fed to mosquitoes 24 h prior to an infective bloodmeal (SM1 = 41%, PLA2 = 23%). Furthermore, prevalence and numbers of engineered bacteria increased dramatically following a bloodmeal. However, E. coli survived poorly in mosquitoes. Therefore, Enterobacter agglomerans was isolated from mosquitoes and selected for midgut survival by multiple passages through mosquitoes. After four passages, E. agglomerans survivorship increased from 2 days to 2 weeks. Since E. agglomerans is non-pathogenic and widespread, it is an excellent candidate for paratransgenic control strategies.