title: Experimental infection of house sparrows (Passer domesticus) with West Nile virus isolates of Euro-Mediterranean and North American origins.
abstract: West Nile virus (WNV) is a zoonotic arboviral pathogen transmitted by mosquitoes in a cycle involving wild birds as reservoir hosts. The virus has recently emerged in North America and re-emerged in Europe. North American WNV outbreaks are often accompanied by high mortality in wild birds, a feature that is uncommon in Europe. The reason for this difference is unknown, but the intrinsic virulence of the viruses circulating in each continent and/or the susceptibility to the disease of Palearctic as opposed to Nearctic wild bird species could play a role. To assess this question, experimental inoculations with four lineage 1 WNV strains, three from southern Europe (Italy/2008, Italy/2009 and Spain/2007) and one from North America (NY99) were performed on house sparrows (Passer domesticus), a wild passerine common in both continents. Non-significant differences which ranged from 0% to 25% were observed in mortality for the different WNV strains. Viremias lasted from 1 to 5-6 days post-inoculation (dpi) in all cases; individuals inoculated with NY99 had significantly higher titres than those inoculated with any of the Euro-Mediterranean strains. Remarkably, host competence was found to be higher for NY99 than for the other strains. Consequently, albeit being pathogenic for house sparrows, some Euro-Mediterranean strains had reduced capacity for replication in -and transmission from- this host, as compared to the NY99 strain. If applicable also to other wild bird host species, this relatively reduced transmission capacity of the Euro-Mediterranean strains could explain the lower incidence of this disease in wild birds in the Euro-Mediterranean area.
authors.forename: Javier
authors.initials: J
authors.lastname: Del Amo
authors.forename: Francisco
authors.initials: F
authors.lastname: Llorente
authors.forename: Jordi
authors.initials: J
authors.lastname: Figuerola
authors.forename: Ramón C
authors.initials: RC
authors.lastname: Soriguer
authors.forename: Ana M
authors.initials: AM
authors.lastname: Moreno
authors.forename: Paolo
authors.initials: P
authors.lastname: Cordioli
authors.forename: Herbert
authors.initials: H
authors.lastname: Weissenböck
authors.affiliation: Centro de Investigación en Sanidad Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (CISA-INIA), Ctra Algete-El Casar s/n, Valdeolmos, Spain. majimenez@inia.es.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Jiménez-Clavero
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001715:Bird Diseases / Q000401:mortality / Q000821:virology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D008297:Male; D016133:Polymerase Chain Reaction / Q000662:veterinary; D013030:Spain / Q000453:epidemiology; D046370:Sparrows; D014766:Viremia / Q000401:mortality / Q000662:veterinary* / Q000821:virology; D014774:Virulence; D014901:West Nile Fever / Q000401:mortality / Q000662:veterinary* / Q000821:virology; D014902:West Nile virus / Q000235:genetics / Q000472:pathogenicity*
chemical_list: D000914:Antibodies, Viral