Dataset Information

Testing of UK Populations of Culex pipiens L. for Schmallenberg Virus Vector Competence and Their Colonization.

ABSTRACT: BACKGROUND:Schmallenberg virus (SBV), an arboviral pathogen of ruminants, emerged in northern Europe during 2011 and has subsequently spread across a vast geographic area. While Culicoides biting midges (Diptera: Ceratopogonidae) have been identified as a biological transmission agent of SBV, the role of mosquitoes (Diptera: Culicidae) as potential vectors has not been defined beyond small-scale field collections in affected areas. Culex pipiens L. are one of the most widespread mosquitoes in northern Europe; they are present on farms across the region and have previously been implicated as vectors of several other arboviruses. We assessed the ability of three colony lines of Cx. pipiens, originating from geographically diverse field populations, to become fully infected by SBV using semi-quantitative real-time RT-PCR (sqPCR). FINDINGS:Two colony lines of Cx. pipiens were created in the UK ('Brookwood' and 'Caldbeck') from field collections of larvae and pupae and characterised using genetic markers. A third strain of Cx. pipiens from CVI Wageningen, The Netherlands, was also screened during experiments. Intrathoracic inoculation of the Brookwood line resulted in infections after 14 days that were characterised by high levels of RNA throughout individuals, but which demonstrated indirect evidence of salivary gland barriers. Feeding of 322 individuals across the three colony lines on a membrane based infection system resulted in no evidence of full dissemination of SBV, although infections did occur in a small proportion of Cx. pipiens from each line. CONCLUSIONS/SIGNIFICANCE:This study established two novel lines of Cx. pipiens mosquitoes of UK origin in the laboratory and subsequently tested their competence for SBV. Schmallenberg virus replication and dissemination was restricted, demonstrating that Cx. pipiens is unlikely to be an epidemiologically important vector of the virus in northern Europe.

SUBMITTER: Manley R

PROVIDER: S-EPMC4546389 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Testing of UK Populations of Culex pipiens L. for Schmallenberg Virus Vector Competence and Their Colonization.

Manley Robyn R Harrup Lara E LE Veronesi Eva E Stubbins Francesca F Stoner Jo J Gubbins Simon S Wilson Anthony A Batten Carrie C Koenraadt Constantianus J M CJ Henstock Mark M Barber James J Carpenter Simon S

PloS one 20150820 8

<h4>Background</h4>Schmallenberg virus (SBV), an arboviral pathogen of ruminants, emerged in northern Europe during 2011 and has subsequently spread across a vast geographic area. While Culicoides biting midges (Diptera: Ceratopogonidae) have been identified as a biological transmission agent of SBV, the role of mosquitoes (Diptera: Culicidae) as potential vectors has not been defined beyond small-scale field collections in affected areas. Culex pipiens L. are one of the most widespread mosquito ...[more]

PMID: 26291533

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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.

Project description:BackgroundUnderstanding mechanisms that contribute to viral dissemination in mosquito vectors will contribute to our ability to interfere with the transmission of viral pathogens that impact public health. The expression of genes in two Culex pipiens quinquefasciatus populations from Florida with known differences in vector competence to West Nile virus (WNV) were compared using high throughput sequencing.ResultsA total of 15,176 transcripts were combined for comparison of expression differences between the two populations and 118 transcripts were differentially expressed (p < 0.05). The fold change in expression of the differentially expressed genes ranged from -7.5 - 6.13. The more competent population for WNV (Gainesville) over expressed 77 genes and down regulated 44 genes, compared with the less competent population for WNV (Vero Beach). Also, splicing analysis identified 3 transcripts with significantly different splice forms between the two populations. The functional analysis showed that the largest proportion of transcripts was included in the catalytic activity and transporter activity groups except for those in the unknown group. Interestingly, the up- regulated gene set contained most of the catalytic activity function and the down- regulated gene set had a notable proportion of transcripts with transporter activity function. Immune response category was shown in only the down regulated gene set, although those represent a relatively small portion of the function. Several different vitellogenin genes were expressed differentially. Based on the RNAseq data analysis, ovary development was compared across the populations and following WNV infection. There were significant differences among the compared groups.ConclusionsThis study suggests that ovary development is correlated to vector competence in two Culex populations in Florida. Both populations control energy allocations to reproduction as a response to WNV. This result provides novel insight into the defense mechanism used by Culex spp. mosquitoes against WNV.

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.

Dataset Information

Testing of UK Populations of Culex pipiens L. for Schmallenberg Virus Vector Competence and Their Colonization.

Publications

Testing of UK Populations of Culex pipiens L. for Schmallenberg Virus Vector Competence and Their Colonization.

Similar Datasets

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