Induction of defensin response to dengue infection in Aedes aegypti

Abstract

© 2014 The Entomological Society of Japan. Innate immune-related defensin peptide expression, the major antimicrobial peptide (AMP) in the dengue vector mosquito Aedes aegypti, was analyzed following infection by dengue virus type 2 (strain 16681) (DENV-2). In vitro, the mosquito cell line C6/36 was exposed to dengue virus at different multiplicities of infection (MOI) in an hour; it was found that the expression level of defensin transcripts was dependent upon viral dose. In addition, using both polymerase chain reaction (PCR) and Western blotting assays to determine defensin transcription and translation at a series of times post-inoculation, we found that the time course of defensin transcripts correlated with the expression of defensin peptide post-infection. In vitro, female Ae. aegypti mosquitoes were fed different meals (DENV-2 infected blood, non-infectious blood and sugar) at 14 days post-feeding, to determine defensin transcription in response to dengue infection, by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) assay. The results showed that a peak of 4.25kDa peptide, composed of defensin, was predominantly induced by DENV-2 infected blood-fed mosquitoes. We observed that DENV-2 could trigger the defensin peptide, defined molecularly as an innate immune response. Therefore, this peptide may be involved in dengue infection and/or transmission. Improved understanding of the mosquito's responses to dengue virus should strengthen our understanding of this vector's innate immune system.