Inhibition of defensin and cecropin responses to dengue virus 1 infection in Aedes aegypti

Abstract

Introduction. It is essential to determine the interactions between viruses and mosquitoes to diminish dengue viral transmission. These interactions constitute a very complex system of highly regulated pathways called the Innate Immune System of mosquito that produces effector molecules like antimicrobial peptides (AMP). These AMP function against bacterial and fungal infections, but on virus infections, there is less information. Objective. To determine the expression of two AMP genes (Defensin A and Cecropin A genes) in Aedes aegypti mosquitoes infected with DENV-1. Materials and methods. The F1 generation of mosquitoes orally infected with DENV-1 was used. Infection assays in conjunction with real-time PCR analysis were used to determine whether the Defensin A and Cecropin A genes have potential roles in controlling DENV-1 replication in Ae. aegypti. As a reference, similar experiments were performed with bacteria Escherichia coli Results. Basal levels of defensin A and cecropin A mRNAs were expressed in uninfected mosquitoes at different times post-blood feeding. The infected mosquitoes experienced reduced expression of these mRNAs by at least eightfold when compared to uninfected control mosquitoes at all time post-infection. In contrast with the behavior of DENV-1, results show that bacterial infection produced up-regulation of Defensin and Cecropin genes; however, the induction of transcripts occurred at later times (15 days). Conclusion. DENV-1 virus inhibits the expression of Defensin A and Cecropin A genes of wild Ae. aegypti population from Venezuela.