The Wolbachia strain wAu provides highly efficient virus transmission blocking in Aedes aegypti.

Thomas H Ant,Vincent Geoghegan,Ary A Hoffmann,Christie S Herd,Steven P Sinkins,David S Schneider

doi:10.1371/journal.ppat.1006815

Abstract

Introduced transinfections of the inherited bacteria Wolbachia can inhibit transmission of viruses by Aedes mosquitoes, and in Ae. aegypti are now being deployed for dengue control in a number of countries. Only three Wolbachia strains from the large number that exist in nature have to date been introduced and characterized in this species. Here novel Ae. aegypti transinfections were generated using the wAlbA and wAu strains. In its native Ae. albopictus, wAlbA is maintained at lower density than the co-infecting wAlbB, but following transfer to Ae. aegypti the relative strain density was reversed, illustrating the strain-specific nature of Wolbachia-host co-adaptation in determining density. The wAu strain also reached high densities in Ae. aegypti, and provided highly efficient transmission blocking of dengue and Zika viruses. Both wAu and wAlbA were less susceptible than wMel to density reduction/incomplete maternal transmission resulting from elevated larval rearing temperatures. Although wAu does not induce cytoplasmic incompatibility (CI), it was stably combined with a CI-inducing strain as a superinfection, and this would facilitate its spread into wild populations. Wolbachia wAu provides a very promising new option for arbovirus control, particularly for deployment in hot tropical climates.

Highlights

The mosquito Aedes aegypti (Linneaus) is the most important vector of human arboviruses
A novel control strategy that is currently being trialed in several countries utilizes Ae. aegypti mosquitoes artificially infected with a bacterial symbiont known as Wolbachia pipientis
We show that one of the strains, wAu, provides strong blocking of dengue and Zika virus transmission and offers greater stability at higher temperatures when compared to wMel —currently the most widely used strain for field releases

Summary

Introduction

The mosquito Aedes aegypti (Linneaus) is the most important vector of human arboviruses. An emerging vector control strategy utilizes mosquitoes artificially transinfected with virus-blocking strains of the alpha-proteobacterium Wolbachia pipientis [3]. Wolbachia are obligate intracellular endosymbionts naturally found infecting a wide range of terrestrial arthropods. The natural abundance of Wolbachia can be partly attributed to its capacity to spread through naïve populations by manipulating host reproduction. Wolbachia modifies the sperm of infected males [4], which results in the generation of non-viable progeny when mated to uninfected females. In contrast, ‘rescue’ this sperm modification, producing viable progeny and resulting in a relative fitness advantage that can drive and maintain Wolbachia at high population infection frequencies [5]

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