title: Naturally induced humoral immunity to West Nile virus infection in raptors.
abstract: West Nile virus (WNV) infection can be fatal to many bird species, including numerous raptors, though population- and ecosystem-level impacts following introduction of the virus to North America have been difficult to document. Raptors occupy a diverse array of habitats worldwide and are important to ecosystems for their role as opportunistic predators. We documented initial (primary) WNV infection and then regularly measured WNV-specific neutralizing antibody titers in 16 resident raptors of seven species, plus one turkey vulture. Most individuals were initially infected and seroconverted between July and September of 2003, though three birds remained seronegative until summer 2006. Many of these birds became clinically ill upon primary infection, with clinical signs ranging from loss of appetite to moderate neurological disease. Naturally induced WNV neutralizing antibody titers remained essentially unchanged in some birds, while eight individuals experienced secondary rises in titer presumably due to additional exposures at 1, 2, or 3 years following primary infection. No birds experienced clinical signs surrounding or following the time of secondary exposure, and therefore antibodies were considered protective. Results of this study have implications for transmission dynamics of WNV and health of raptor populations, as well as the interpretation of serologic data from free-ranging and captive birds. Antibodies in raptors surviving WNV may persist for multiple years and protect against potential adverse effects of subsequent exposures.
authors.affiliation: Arbovirus Diseases Branch, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA. nnemeth@colostate.edu
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Nemeth
authors.forename: Gail E
authors.initials: GE
authors.lastname: Kratz
authors.forename: Rebecca
authors.initials: R
authors.lastname: Bates
authors.forename: Judy A
authors.initials: JA
authors.lastname: Scherpelz
authors.forename: Richard A
authors.initials: RA
authors.lastname: Bowen
authors.forename: Nicholas
authors.initials: N
authors.lastname: Komar
mesh_terms: D000818:Animals; D000917:Antibody Formation; D001715:Bird Diseases / Q000276:immunology*; D004197:Disease Reservoirs; D009656:North America; D020304:Raptors / Q000821:virology*; D010948:Viral Plaque Assay; D014901:West Nile Fever / Q000276:immunology / Q000662:veterinary*; D014902:West Nile virus / Q000276:immunology*