Abstract
BackgroundArthropod-borne viruses (arboviruses) can persistently infect and cause limited damage to mosquito vectors. RNA interference (RNAi) is a mosquito antiviral response important in restricting RNA virus replication and has been shown to be active against some arboviruses. The goal of this study was to use a recombinant Sindbis virus (SINV; family Togaviridae; genus Alphavirus) that expresses B2 protein of Flock House virus (FHV; family Nodaviridae; genus Alphanodavirus), a protein that inhibits RNAi, to determine the effects of linking arbovirus infection with RNAi inhibition.ResultsB2 protein expression from SINV (TE/3'2J) inhibited the accumulation of non-specific small RNAs in Aedes aegypti mosquito cell culture and virus-specific small RNAs both in infected cell culture and Ae. aegypti mosquitoes. More viral genomic and subgenomic RNA accumulated in cells and mosquitoes infected with TE/3'2J virus expressing B2 (TE/3'2J/B2) compared to TE/3'2J and TE/3'2J virus expressing GFP. TE/3'2J/B2 exhibited increased infection rates, dissemination rates, and infectious virus titers in mosquitoes following oral bloodmeal. Following infectious oral bloodmeal, significantly more mosquitoes died when TE/3'2J/B2 was ingested. The virus was 100% lethal following intrathoracic inoculation of multiple mosquito species and lethality was dose-dependent in Ae. aegypti.ConclusionWe show that RNAi is active in Ae. aegypti cell culture and that B2 protein inhibits RNAi in mosquito cells when expressed by a recombinant SINV. Also, SINV more efficiently replicates in mosquito cells when RNAi is inhibited. Finally, TE/3'2J/B2 kills mosquitoes in a dose-dependent manner independent of infection route and mosquito species.
Highlights
IntroductionArthropod-borne viruses (arboviruses) can persistently infect and cause limited damage to mosquito vectors
Arthropod-borne viruses can persistently infect and cause limited damage to mosquito vectors
Inhibition of RNA interference (RNAi) by a Sindbis virus (SINV)-expressed viral suppressor of RNA silencing (VSR) After rescue of infectious virus from cDNA-derived RNA, expression of V5 epitope-tagged B2 protein from the second subgenomic promoter was verified by immunoblot analysis of total protein from infected Aag2 cells
Summary
Arthropod-borne viruses (arboviruses) can persistently infect and cause limited damage to mosquito vectors. RNA interference (RNAi) is a mosquito antiviral response important in restricting RNA virus replication and has been shown to be active against some arboviruses. Arthropod-borne viruses (arboviruses) such as Sindbis and Chikungunya viruses are transmitted to humans through the bite of an infected mosquito. Virus persists in the mosquito vector with minimal associated pathology. BMC Microbiology 2009, 9:49 http://www.biomedcentral.com/1471-2180/9/49 described with laboratory-infected mosquitoes, but little is known about the interplay between virus and vector that allows for sustainable arbovirus infection in the environment [1,2,3,4,5]. The persistent nature of arbovirus infection of a vector suggests a commensal rather than parasitic relationship. A factor of particular interest in this relationship is the interaction of viral replication and the mosquito RNA interference (RNAi) response to infection
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