title: Phylogenetic characterization of Central/Southern European lineage 2 West Nile virus: analysis of human outbreaks in Italy and Greece, 2013-2014.
abstract: In recent years, West Nile virus (WNV) lineage 2 has been spreading and causing disease outbreaks in humans and animals in Europe. In order to characterize viral diversity, we performed full-length genome sequencing of WNV lineage 2 from human samples collected during outbreaks in Italy and Greece in 2013 and 2014. Phylogenetic analysis showed that these WNV lineage 2 genomes belonged to a monophyletic clade derived from a single introduction into Europe of the prototype Hungarian strain. Correlation of phylogenetic data with geospatial information showed geographical clustering of WNV genome sequences both in Italy and in Greece, indicating that the virus had evolved and diverged during its dispersal in Europe, leading to the emergence of novel genotypes, as it adapted to local ecological niches. These genotypes carried divergent conserved amino acid substitutions, which might have been relevant for viral adaptation, as suggested by selection pressure analysis and in silico and experimental modelling of sequence changes. In conclusion, the results of this study provide further information on WNV lineage 2 transmission dynamics in Europe, and emphasize the need for WNV surveillance activities to monitor viral evolution and diversity.
authors.affiliation: Department of Molecular Medicine, University of Padova, Padova, Italy; Microbiology and Virology Unit, Padova University Hospital, Padova, Italy. Electronic address: luisa.barzon@unipd.it.
authors.forename: L
authors.initials: L
authors.lastname: Barzon
authors.affiliation: National Reference Centre for Arboviruses, Department of Microbiology, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Papa
authors.affiliation: Department of Molecular Medicine, University of Padova, Padova, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Lavezzo
authors.affiliation: Department of Molecular Medicine, University of Padova, Padova, Italy; Microbiology and Virology Unit, Padova University Hospital, Padova, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Franchin
authors.affiliation: Microbiology and Virology Unit, Padova University Hospital, Padova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Pacenti
authors.affiliation: IRCCS-IOV Istituto Oncologico Veneto, Padova, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Sinigaglia
authors.affiliation: Department of Molecular Medicine, University of Padova, Padova, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Masi
authors.affiliation: Department of Molecular Medicine, University of Padova, Padova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Trevisan
authors.affiliation: Department of Molecular Medicine, University of Padova, Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Squarzon
authors.affiliation: Department of Molecular Medicine, University of Padova, Padova, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Toppo
authors.affiliation: National Reference Centre for Arboviruses, Department of Microbiology, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: E
authors.initials: E
authors.lastname: Papadopoulou
authors.affiliation: Institute of Virology, University of Veterinary Medicine, Vienna, Austria; Department of Microbiology and Immunology, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman.
authors.forename: N
authors.initials: N
authors.lastname: Nowotny
authors.affiliation: Department of Immunology, Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Ulbert
authors.affiliation: Molecular Virology Unit, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Piralla
authors.affiliation: Molecular Virology Unit, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Rovida
authors.affiliation: Molecular Virology Unit, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; Department of Clinical Sciences, Surgery, Diagnostics and Paediatrics, University of Pavia, Pavia, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Baldanti
authors.affiliation: Molecular Virology Unit, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Percivalle
authors.affiliation: Department of Molecular Medicine, University of Padova, Padova, Italy; Microbiology and Virology Unit, Padova University Hospital, Padova, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Palù
mesh_terms: D019943:Amino Acid Substitution; D004196:Disease Outbreaks; D019143:Evolution, Molecular; D016679:Genome, Viral; D006115:Greece; D006801:Humans; D007558:Italy; D008958:Models, Molecular; D010802:Phylogeny; D058974:Phylogeography; D012367:RNA, Viral / Q000235:genetics*; D017423:Sequence Analysis, RNA; D014901:West Nile Fever / Q000453:epidemiology* / Q000635:transmission; D014902:West Nile virus / Q000145:classification* / Q000235:genetics*
chemical_list: D012367:RNA, Viral
keywords: Europe; Greece; Italy; WNV lineage 1; WNV lineage 2; West Nile virus; genetic evolution; genome sequencing; molecular epidemiology; phylogenetic analysis