Culex pipiens pipiens: characterization of immune peptides and the influence of immune activation on development of Wuchereria bancrofti.

Stimulating or augmenting the innate immune response of insect vectors has been shown to impede or disrupt the development and transmission of eukaryotic pathogens; however, the majority of such studies have utilized model systems and not natural parasite-vector systems. The Culex pipiens complex of mosquitoes functions as a primary urban vector of Wuchereria bancrofti, a causative agent of lymphatic filariasis. To test the effects of immune activation on this vector-parasite interaction, Culex pipiens pipiens from the filariasis-endemic Nile Delta were subjected to bacteria inoculation and subsequently fed a blood meal containing W. bancrofti. No difference was seen between parasite development in these mosquitoes as compared to non-inoculated controls. A set of expressed sequence tags from blood-fed midgut and bacteria-inoculated Cx. p. pipiens reveals transcripts for the immune peptides cecropin, gambicin and defensin--all of which have been reported to have antiparasitic effects. Sequences and transcriptional profiles for these peptides are reported. The discrepancy between these results and those reported for the model parasite, Brugia malayi, in the mosquito Aedes aegypti are discussed.