Transgene‐mediated suppression of dengue viruses in the salivary glands of the yellow fever mosquito, Aedes aegypti

Abstract

Controlled sex-, stage-and tissue-specific expression of anti-pathogen effector molecules is important for genetic engineering strategies to control mosquito-borne diseases. Adult female salivary glands are involved in pathogen transmission to human hosts and are target sites for expression of anti-pathogen effector molecules. The Aedes aegypti 30K a and 30K b genes are expressed exclusively in adult female salivary glands and are transcribed divergently from start sites separated by 263 nucleotides. The intergenic, 5'-and 3'-end untranslated regions of both genes are sufficient to express simultaneously two different transgene products in the distal-lateral lobes of the female salivary glands. An anti-dengue effector gene, Mnp, driven by the 30K b promoter, expresses an inverted-repeat RNA with sequences derived from the premembrane protein-encoding region of the dengue virus serotype 2 genome and reduces significantly the prevalence and mean intensities of viral infection in mosquito salivary glands and saliva.

Genetic control ofAedesmosquitoes

“…78 For the arboviruses transmitted by Aedes mosquitoes, RNAi seems an attractive mechanism for suppressing virus replication. Transgene-based expression of a hairpin RNA corresponding to part of the DEN2 virus in either the midgut 79 or salivary glands 80 has been shown to provide a strong block to virus transmission. However, for the midgut-expressing line, expression of the anti-DEN2 hairpin and the associated refractory phenotype were lost after about 13 generations, 81 suggesting that expression may impose a significant fitness cost, and also perhaps that the unusual inverted repeat structure involved may be subject to some form of epigenetic silencing.…”

Criteria for Identifying and Evaluating Candidate Sites for Open-Field Trials of Genetically Engineered Mosquitoes

“…Significant advancements have been made in the discovery of genetic-based products to control vector-borne diseases (some examples for addressing transmission of dengue viruses are included in Franz et al 2006, Phuc et al 2007, Nawtaisong et al 2009, Fu et al 2010, Mathur et al 2010, Labbé et al 2012. Efforts to develop a population-suppression strain based on a refinement of a female-killing strategy (Black et al 2011) yielded transgenic Aedes aegypti carrying a conditional dominant gene that rendered females unable to fly (Fu et al 2010).…”

Pathogen-insect interaction candidate molecules for transmission-blocking control strategies of vector borne diseases

“…aegypti expressing in the midgut and salivary glands inverted RNA coding for a region of the pre-membrane viral protein depicted lower susceptibility to DENV. 43,44 Trypanosoma cruzi. Trypomastigotes ingested in the blood meal remain for few days in the anterior part of the insect midgut; most of them transform into epimastigotes, and move to the posterior part of the midgut.…”