Ross River Virus Provokes Differentially Expressed MicroRNA and RNA Interference Responses in Aedes aegypti Mosquitoes.

James B Sinclair,Sassan Asgari

doi:10.3390/v12070695

Abstract

Alphaviruses are globally distributed and predominately transmitted by mosquitoes. Aedes species are common vectors for the clinically important alphaviruses—Chikungunya, Sindbis, and Ross River (RRV) viruses—with Aedes aegypti also being a vector for the flaviviruses dengue, Yellow Fever, and Zika viruses. Ae. aegypti was putatively implicated in the large 1979–1980 South Pacific Islands outbreak of RRV—the leading cause of arboviral disease in Australia today. The RNA interference (RNAi) defense response in mosquitoes involves a number of small RNAs, with their kinetics induced by alphaviruses being poorly understood, particularly at the tissue level. We compared the small RNA profiles between RRV-infected and non-infected Ae. aegypti midgut and fat body tissues at 2, 6, and 12 days post-inoculation (dpi). RRV induced an incremental RNAi response, yielding short interfering and P-element-induced-wimpy-testis (PIWI)-interacting RNAs. Fourteen host microRNAs were differentially expressed due to RRV with the majority in the fat body at 2 dpi. The largely congruent pattern of microRNA regulation with previous reports for alphaviruses and divergence from those for flaviviruses suggests a degree of conservation, whereas patterns of microRNA expression unique to this study provide novel insights into the tissue-specific host-virus attributes of Ae. aegypti responses to this previously unexplored old-world alphavirus.

Highlights

Members of the Alphavirus genus (Togaviridae) are mosquito-borne enveloped RNA viruses that are globally distributed, and those of medical significance are attributed to causing encephalitic (e.g., Eastern (EEEV), Western (WEEV), and Venezuelan Equine Encephalitis (VEEV) viruses) or arthritogenic (e.g., Ross River virus (RRV), Chikungunya virus (CHIKV), and the archetypal Sindbis virus (SINV)) diseases [1]
The rates of viral infection were determined from a subset of mosquitoes (N = 10) from days 2, 6, and 12 and the relative viral load in those mosquitoes with individual mosquitoes (N = 10) from days 2, 6, and 12 and the relative viral load in those mosquitoes a detectable degree of RRV infection (N = 6) was confirmed by reverse transcription quantitative PCR (RT-qPCR), which demonstrated a with a detectable degree of RRV infection (N = 6) was confirmed by RT‐qPCR, which demonstrated progressive increase in viral load over time (Figure 1)
Considering that carcasses were used for determination of virus infection after dissection of tissues, 100% dissemination of virus at 12 dpi suggested high rate of infection even if it dissection of tissues, 100% dissemination of virus at 12 dpi suggested high rate of infection even if it was detected in about 50% of mosquito carcasses at 2 dpi when virus was at early stages of infection in was detected in about 50% of mosquito carcasses at 2 dpi when virus was at early stages of infection the midgut, which was already removed from mosquito bodies

Summary

Introduction

Members of the Alphavirus genus (Togaviridae) are mosquito-borne enveloped RNA viruses that are globally distributed, and those of medical significance are attributed to causing encephalitic (e.g., Eastern (EEEV), Western (WEEV), and Venezuelan Equine Encephalitis (VEEV) viruses) or arthritogenic (e.g., Ross River virus (RRV), Chikungunya virus (CHIKV), and the archetypal Sindbis virus (SINV)) diseases [1]. Transmission cycles encroach into urban environments via short-term amplifying hosts such as peridomestic animals (e.g., bats, birds, cats, dogs, or possums), during epidemics, transmission cycles that are entirely urban (human–mosquito–human) can occur in densely populated regions [3]. RRV is an arthritogenic virus endemic to Australia, Papua New Guinea, and South Pacific. The virus causes epidemic polyarthritis (EPA; otherwise known as Ross River disease or fever) and is the leading cause of viral disease in Australia with a rolling annual mean between. On the basis of previous estimates and factoring in inflation, the national cost of EPA in 2018 exceeded AUD 9.3 million in medical expenses, whereas the true

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