Mapping the virome in wild-caught Aedes aegypti from Cairns and Bangkok

Martha Zakrzewski,Igor Filipović,Rhys Parry,Greg Devine,Sassan Asgari,Yee S Poo,Jonathan Darbro,Andreas Suhrbier,Gordana Rašić,Lutz Krause

doi:10.1038/s41598-018-22945-y

Abstract

Medically important arboviruses such as dengue, Zika, and chikungunya viruses are primarily transmitted by the globally distributed mosquito Aedes aegypti. Increasing evidence suggests that transmission can be influenced by mosquito viromes. Herein RNA-Seq was used to characterize RNA metaviromes of wild-caught Ae. aegypti from Bangkok (Thailand) and from Cairns (Australia). The two mosquito populations showed a high degree of similarity in their viromes. BLAST searches of assembled contigs suggest up to 27 insect-specific viruses may infect Ae. aegypti, with up to 23 of these currently uncharacterized and up to 16 infecting mosquitoes from both Cairns and Bangkok. Three characterized viruses dominated, Phasi Charoen-like virus, Humaita-Tubiacanga virus and Cell fusing agent virus, and comparisons with other available RNA-Seq datasets suggested infection levels with these viruses may vary in laboratory-reared mosquitoes. As expected, mosquitoes from Bangkok showed higher mitochondrial diversity and carried alleles associated with knock-down resistance to pyrethroids. Blood meal reads primarily mapped to human genes, with a small number also showing homology with rat/mouse and dog genes. These results highlight the wide spectrum of data that can be obtained from such RNA-Seq analyses, and suggests differing viromes may need to be considered in arbovirus vector competence studies.

Highlights

The mosquito Aedes aegypti is a primary vector for transmission of a number of arboviruses such as dengue, Zika, and chikungunya viruses that infect tens of millions of people in tropical and subtropical regions around the globe every year
The analysis suggested up to 23 new uncharacterized ISVs are present in Ae. aegypti populations
A number aligned to mouse/rat genes (79 for Cairns and 190 for Bangkok), 5 Bangkok reads aligned to dog genes, and 1 Cairns and 1 Bangkok read aligned to cow genes (Table S6). These reads all aligned with lower scores to human genes (Table S6), supporting the view they were not derived from human genes. Taken together these results argue that RNA-Seq is able to identify mosquito blood meal hosts

Summary

Introduction

The mosquito Aedes aegypti is a primary vector for transmission of a number of arboviruses such as dengue, Zika, and chikungunya viruses that infect tens of millions of people in tropical and subtropical regions around the globe every year. We use a metagenomic approach to describe the virome of two wild-caught, geographically distant Ae. aegypti populations, one from Cairns (Australia) collected in 2014 and one from Bangkok (Thailand) collected in 2015. Both mosquito populations are associated with dengue transmission. The study highlights the range of data that can be obtained from such analyses, and provides an initial map of the diversity and abundance of ISV infections in wild-caught Ae. aegypti. While the viromes of wild-caught Ae. aegypti from Cairns and Bangkok were surprisingly similar, analyses of other available RNA-Seq data sets suggested that the levels of major ISVs in laboratory reared mosquitoes may be different

Methods

Results

Conclusion