European Aedes albopictus and Culex pipiens Are Competent Vectors for Japanese Encephalitis Virus.
PLoS Negl Trop Dis 2017;
11:e0005294. [PMID:
28085881 PMCID:
PMC5268654 DOI:
10.1371/journal.pntd.0005294]
[Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 01/26/2017] [Accepted: 01/02/2017] [Indexed: 11/19/2022] Open
Abstract
Background
Japanese encephalitis virus (JEV) is the causative agent of Japanese encephalitis, the leading cause of viral encephalitis in Asia. JEV transmission cycle involves mosquitoes and vertebrate hosts. The detection of JEV RNA in a pool of Culex pipiens caught in 2010 in Italy raised the concern of a putative emergence of the virus in Europe. We aimed to study the vector competence of European mosquito populations, such as Cx. pipiens and Aedes albopictus for JEV genotypes 3 and 5.
Findings
After oral feeding on an infectious blood meal, mosquitoes were dissected at various times post-virus exposure. We found that the peak for JEV infection and transmission was between 11 and 13 days post-virus exposure. We observed a faster dissemination of both JEV genotypes in Ae. albopictus mosquitoes, when compared with Cx. pipiens mosquitoes. We also dissected salivary glands and collected saliva from infected mosquitoes and showed that Ae. albopictus mosquitoes transmitted JEV earlier than Cx. pipiens. The virus collected from Ae. albopictus and Cx. pipiens saliva was competent at causing pathogenesis in a mouse model for JEV infection. Using this model, we found that mosquito saliva or salivary glands did not enhance the severity of the disease.
Conclusions
In this study, we demonstrated that European populations of Ae. albopictus and Cx. pipiens were efficient vectors for JEV transmission. Susceptible vertebrate species that develop high viremia are an obligatory part of the JEV transmission cycle. This study highlights the need to investigate the susceptibility of potential JEV reservoir hosts in Europe, notably amongst swine populations and local water birds.
Japanese encephalitis virus (JEV) is the leading cause of viral encephalitis in Asia. JEV is maintained in a cycle involving mosquitoes and vertebrate hosts, mainly pigs and wading birds. Humans can be infected when bitten by an infected mosquito. Culex tritaeniorhynchus is the main vector of the disease in tropical and subtropical areas. The recent detection of JEV in birds and mosquitoes collected in Northern Italy has led us to evaluate the putative emergence of this arboviral disease in Europe. For this purpose, we have tested the competence of European populations of Cx. pipiens and Aedes albopictus to transmit this virus in a laboratory setting. We showed that these local mosquitoes could be infected and were capable of transmitting a pathogenic virus to mice. It is thus urgent to evaluate the risks of JEV emergence in European regions displaying a favorable environment for mosquito vectors, susceptible pigs and wading birds.
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