Dataset Information

First Detection and Molecular Characterization of Usutu Virus in Culex pipiens Mosquitoes Collected in Romania.

ABSTRACT: Usutu virus (USUV) is an emergent arbovirus in Europe causing mortality in bird populations. Similar to West Nile virus (WNV), USUV is maintained in sylvatic cycles between mosquito vectors and bird reservoirs. Spillover events may result in human neurological infection cases. Apart from indirect evidence provided by a recent serological study in wild birds, the circulation of USUV in Romania was not assessed. We aimed to detect and molecular characterize USUV circulating in mosquito vectors collected in South-Eastern Romania-a well-known WNV endemic region-during four transmission seasons. Mosquitoes were collected from Bucharest metropolitan area and Danube Delta, pooled, and screened by real-time RT-PCR for USUV. Partial genomic sequences were obtained and used for phylogeny. USUV was detected in Culex pipiens s.l. female mosquitoes collected in Bucharest, in 2019. The virus belonged to Europe 2 lineage, sub-lineage EU2-A. Phylogenetic analysis revealed high similarity with isolates infecting mosquito vectors, birds, and humans in Europe starting with 2009, all sharing common origin in Northern Italy. To our knowledge, this is the first study characterizing a strain of USUV circulating in Romania.

SUBMITTER: Prioteasa FL

PROVIDER: S-EPMC10054730 | biostudies-literature | 2023 Mar

REPOSITORIES: biostudies-literature

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First Detection and Molecular Characterization of Usutu Virus in <i>Culex pipiens</i> Mosquitoes Collected in Romania.

Prioteasa Florian Liviu FL Dinu Sorin S Tiron Georgiana Victorița GV Stancu Ioana Georgeta IG Fălcuță Elena E Ceianu Cornelia Svetlana CS Cotar Ani Ioana AI

Microorganisms 20230307 3

Usutu virus (USUV) is an emergent arbovirus in Europe causing mortality in bird populations. Similar to West Nile virus (WNV), USUV is maintained in sylvatic cycles between mosquito vectors and bird reservoirs. Spillover events may result in human neurological infection cases. Apart from indirect evidence provided by a recent serological study in wild birds, the circulation of USUV in Romania was not assessed. We aimed to detect and molecular characterize USUV circulating in mosquito vectors col ...[more]

PMID: 36985256

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Project description:BackgroundUsutu virus (USUV) is a rapidly spreading zoonotic arbovirus (arthropod-borne virus) and a considerable threat to the global avifauna and in isolated cases to human health. It is maintained in an enzootic cycle involving ornithophilic mosquitoes as vectors and birds as reservoir hosts. Despite massive die-offs in wild bird populations and the detection of severe neurological symptoms in infected humans, little is known about which mosquito species are involved in the propagation of USUV.MethodsIn the present study, the vector competence of a German (i.e. "Central European") and a Serbian (i.e. "Southern European") Culex pipiens biotype molestus laboratory colony was experimentally evaluated. For comparative purposes, Culex torrentium, a frequent species in Northern Europe, and Aedes aegypti, a primarily tropical species, were also tested. Adult female mosquitoes were exposed to bovine blood spiked with USUV Africa 2 and subsequently incubated at 25 °C. After 2 to 3 weeks saliva was collected from each individual mosquito to assess the ability of a mosquito species to transmit USUV.ResultsCulex pipiens biotype molestus mosquitoes originating from Germany and the Republic of Serbia and Cx. torrentium mosquitoes from Germany proved competent for USUV, as indicated by harboring viable virus in their saliva 21 days post infection. By contrast, Ae. aegypti mosquitoes were relatively refractory to an USUV infection, exhibiting low infection rates and lacking virus in their saliva.ConclusionsConsistent with the high prevalences and abundances of Cx. pipiens biotype molestus and Cx. torrentium in Central and Northern Europe, these two species have most likely played a historic role in the spread, maintenance, and introduction of USUV into Germany. Identification of the key USUV vectors enables the establishment and implementation of rigorous entomological surveillance programs and the development of effective, evidence-based vector control interventions.

Project description:BackgroundInfectious blood meal experiments have been frequently performed with different virus-vector combinations to assess the transmission potential of arthropod-borne (arbo)viruses. A wide variety of host blood sources have been used to deliver arboviruses to their arthropod vectors in laboratory studies. The type of blood used during vector competence experiments does not always reflect the blood from the viremic vertebrate hosts in the field, but little is known about the effect of blood source on the experimental outcome of vector competence studies. Here we investigated the effect of avian versus human blood on the infection and transmission rates of the zoonotic Usutu virus (USUV) in its primary mosquito vector Culex pipiens.MethodsCx. pipiens biotypes (pipiens and molestus) were orally infected with USUV through infectious blood meals containing either chicken or human whole blood. The USUV infection and transmission rates were determined by checking mosquito bodies and saliva for USUV presence after 14 days of incubation at 28 °C. In addition, viral titers were determined for USUV-positive mosquito bodies and saliva.ResultsHuman and chicken blood lead to similar USUV transmission rates for Cx. pipiens biotype pipiens (18% and 15%, respectively), while human blood moderately but not significantly increased the transmission rate (30%) compared to chicken blood (17%) for biotype molestus. USUV infection rates with human blood were consistently higher in both Cx. pipiens biotypes compared to chicken blood. In virus-positive mosquitoes, USUV body and saliva titers did not differ between mosquitoes taking either human or chicken blood. Importantly, biotype molestus had much lower USUV saliva titers compared to biotype pipiens, regardless of which blood was offered.ConclusionsInfection of mosquitoes with human blood led to higher USUV infection rates as compared to chicken blood. However, the blood source had no effect on the vector competence for USUV. Interestingly, biotype molestus is less likely to transmit USUV compared to biotype pipiens due to very low virus titers in the saliva.

Dataset Information

First Detection and Molecular Characterization of Usutu Virus in Culex pipiens Mosquitoes Collected in Romania.

Publications

First Detection and Molecular Characterization of Usutu Virus in <i>Culex pipiens</i> Mosquitoes Collected in Romania.

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