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High genetic diversity in the Culex pipiens complex from a West Nile Virus epidemic area in Southern Europe

BACKGROUND: The Culex pipiens complex includes the most widespread mosquito species in the world. Cx. pipiens is the primary vector of the West Nile Virus (WNV) in Europe and North America. Cases of WNV have been recorded in Italy since 1998. In particular, wet areas along the Po River are considere...

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Autores principales: Simonato, Mauro, Martinez-Sañudo, Isabel, Cavaletto, Giacomo, Santoiemma, Giacomo, Saltarin, Andrea, Mazzon, Luca
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4791856/
https://www.ncbi.nlm.nih.gov/pubmed/26979749
http://dx.doi.org/10.1186/s13071-016-1429-1
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author Simonato, Mauro
Martinez-Sañudo, Isabel
Cavaletto, Giacomo
Santoiemma, Giacomo
Saltarin, Andrea
Mazzon, Luca
author_facet Simonato, Mauro
Martinez-Sañudo, Isabel
Cavaletto, Giacomo
Santoiemma, Giacomo
Saltarin, Andrea
Mazzon, Luca
author_sort Simonato, Mauro
collection PubMed
description BACKGROUND: The Culex pipiens complex includes the most widespread mosquito species in the world. Cx. pipiens is the primary vector of the West Nile Virus (WNV) in Europe and North America. Cases of WNV have been recorded in Italy since 1998. In particular, wet areas along the Po River are considered some of the most WNV affected areas in Italy. Here, we analyzed the genetic structure of ten Cx. pipiens populations collected in the last part of the Po River including the Delta area. METHODS: We assessed the genetic variability of two mitochondrial markers, cytochrome oxidase 1 (COI) and 2 (COII), for a total of 1200 bp, and one nuclear marker, a fragment of acetylcholinesterase-2 (ace-2), 502 bp long. The effect of the landscape features was evaluated comparing haplotype and nucleotide diversity with the landscape composition. RESULTS: The analysis showed a high genetic diversity in both COI and COII gene fragments mainly shared by the populations in the Delta area. The COI-COII network showed that the set of haplotypes found was grouped into three main supported lineages with the higher genetic variability gathered in two of the three lineages. By contrast, ace-2 fragment did not show the same differentiation, displaying alleles grouped in a single clade. Finally, a positive correlation between mitochondrial diversity and natural wetland areas was found. CONCLUSIONS: The high mitochondrial genetic diversity found in Cx. pipiens populations from the Po River Delta contrasts with the low variability of inland populations. The different patterns of genetic diversity found comparing mitochondrial and nuclear markers could be explained by factors such as differences in effective population size between markers, sex biased dispersal or lower fitness of dispersing females. Moreover, the correlation between genetic diversity and wetland areas is consistent with ecosystem stability and lack of insecticide pressure characteristic of this habitat. The mtDNA polymorphism found in the Po River Delta is even more interesting due to possible linkages between the mitochondrial lineages and different biting behaviors of the mosquitoes influencing their vector ability of arboviral infections. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13071-016-1429-1) contains supplementary material, which is available to authorized users.
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spelling pubmed-47918562016-03-16 High genetic diversity in the Culex pipiens complex from a West Nile Virus epidemic area in Southern Europe Simonato, Mauro Martinez-Sañudo, Isabel Cavaletto, Giacomo Santoiemma, Giacomo Saltarin, Andrea Mazzon, Luca Parasit Vectors Research BACKGROUND: The Culex pipiens complex includes the most widespread mosquito species in the world. Cx. pipiens is the primary vector of the West Nile Virus (WNV) in Europe and North America. Cases of WNV have been recorded in Italy since 1998. In particular, wet areas along the Po River are considered some of the most WNV affected areas in Italy. Here, we analyzed the genetic structure of ten Cx. pipiens populations collected in the last part of the Po River including the Delta area. METHODS: We assessed the genetic variability of two mitochondrial markers, cytochrome oxidase 1 (COI) and 2 (COII), for a total of 1200 bp, and one nuclear marker, a fragment of acetylcholinesterase-2 (ace-2), 502 bp long. The effect of the landscape features was evaluated comparing haplotype and nucleotide diversity with the landscape composition. RESULTS: The analysis showed a high genetic diversity in both COI and COII gene fragments mainly shared by the populations in the Delta area. The COI-COII network showed that the set of haplotypes found was grouped into three main supported lineages with the higher genetic variability gathered in two of the three lineages. By contrast, ace-2 fragment did not show the same differentiation, displaying alleles grouped in a single clade. Finally, a positive correlation between mitochondrial diversity and natural wetland areas was found. CONCLUSIONS: The high mitochondrial genetic diversity found in Cx. pipiens populations from the Po River Delta contrasts with the low variability of inland populations. The different patterns of genetic diversity found comparing mitochondrial and nuclear markers could be explained by factors such as differences in effective population size between markers, sex biased dispersal or lower fitness of dispersing females. Moreover, the correlation between genetic diversity and wetland areas is consistent with ecosystem stability and lack of insecticide pressure characteristic of this habitat. The mtDNA polymorphism found in the Po River Delta is even more interesting due to possible linkages between the mitochondrial lineages and different biting behaviors of the mosquitoes influencing their vector ability of arboviral infections. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13071-016-1429-1) contains supplementary material, which is available to authorized users. BioMed Central 2016-03-15 /pmc/articles/PMC4791856/ /pubmed/26979749 http://dx.doi.org/10.1186/s13071-016-1429-1 Text en © Simonato et al. 2016 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Simonato, Mauro
Martinez-Sañudo, Isabel
Cavaletto, Giacomo
Santoiemma, Giacomo
Saltarin, Andrea
Mazzon, Luca
High genetic diversity in the Culex pipiens complex from a West Nile Virus epidemic area in Southern Europe
title High genetic diversity in the Culex pipiens complex from a West Nile Virus epidemic area in Southern Europe
title_full High genetic diversity in the Culex pipiens complex from a West Nile Virus epidemic area in Southern Europe
title_fullStr High genetic diversity in the Culex pipiens complex from a West Nile Virus epidemic area in Southern Europe
title_full_unstemmed High genetic diversity in the Culex pipiens complex from a West Nile Virus epidemic area in Southern Europe
title_short High genetic diversity in the Culex pipiens complex from a West Nile Virus epidemic area in Southern Europe
title_sort high genetic diversity in the culex pipiens complex from a west nile virus epidemic area in southern europe
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4791856/
https://www.ncbi.nlm.nih.gov/pubmed/26979749
http://dx.doi.org/10.1186/s13071-016-1429-1
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