Escherichia coli expressing a green fluorescent protein (GFP) in Anopheles stephensi: a preliminary model for paratransgenesis

Issues, like emerging insecticide resistance in Anopheles mosquitoes, have led to a breakdown in many vector control programs. In this study, a recombinant Escherichia coli with plasmid expressing a green fluorescent protein (E.coli-GFP) was used as a paratransgenesis model to determine: the possibility of E. coli-GFP trans-stadial transmission. The effect of the water microflora, of bacteria-impregnated sugar solutions, and of blood-feeding on E. coli-GFP colonization and localization within An. stephensi tissues, were studied. The results demonstrated the persistence of E. coli-GFP during molting and metamorphosis events and its trans-stadial transmission. Also the efficacy of bacteria-impregnated sugar solutions for transferring the bacteria to the adult mosquito's midgut was shown. A blood meal dramatically increased the number of bacteria within 24-48 h post feeding. In addition to fluorescence microscope evaluation, GFP gene PCR amplification showed the presence of the bacteria in the midgut of larvae, pupae, and adults up to 13 days after eclosion. Massive colonization of bacteria was observed in the larvae and in the adult mosquito's malpighian tubules which may play a role in retaining bacteria in adult mosquitos. The results of this study showed that E. coli could be used as a laboratory model in paratransgenesis studies for the evaluation of various effector molecules as anti-parasite agents for malaria and filariasis.