title: West Nile virus-specific immunoglobulin isotype responses in vaccinated and infected horses.
abstract: OBJECTIVE
  To compare antibody responses of horses naturally infected with West Nile virus (WNV) and those vaccinated against WNV, to identify whether vaccination interferes with the ability to diagnose WNV infection, and to determine the duration of antibody responses after vaccination.
  
  
  METHODS
  Sera from horses naturally infected with WNV (n = 10) and adult WNV-naïve horses before and after vaccination with a live canarypox virus-vectored vaccine (7) or a killed virus vaccine (8).
  
  
  METHODS
  An established WNV IgM capture ELISA was used to measure IgM responses. Newly developed capture ELISAs were used to measure responses of 8 other WNV-specific immunoglobulin isotypes. A serum neutralization assay was used to determine anti-WNV antibody titers.
  
  
  RESULTS
  WNV-specific IgM responses were typically detected in the sera of WNV-infected horses but not in sera of horses vaccinated against WNV. Natural infection with and vaccination against WNV induced an immunoglobulin response that was primarily composed of IgG1. West Nile virus-specific IgG1 was detected in the sera of most horses 14 days after vaccination. Serum anti-WNV IgG1 and neutralizing antibody responses induced by the killed-virus vaccines were higher and lasted longer than did those induced by the live canarypox virus-vectored vaccine.
  
  
  CONCLUSIONS
  On the basis of these findings, we recommend that horses be vaccinated against WNV annually near the beginning of mosquito season, that both IgM and IgG1 responses against WNV be measured to distinguish between natural infection and vaccination, and that a WNV IgG1 ELISA be used to monitor anti-WNV antibodies titers in vaccinated horses.
authors.affiliation: Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Khatibzadeh
authors.forename: Carvel B
authors.initials: CB
authors.lastname: Gold
authors.forename: Alison E
authors.initials: AE
authors.lastname: Keggan
authors.forename: Gillian A
authors.initials: GA
authors.lastname: Perkins
authors.forename: Amy L
authors.initials: AL
authors.lastname: Glaser
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Dubovi
authors.forename: Bettina
authors.initials: B
authors.lastname: Wagner
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000917:Antibody Formation; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D006734:Horse Diseases / Q000276:immunology*; D006736:Horses / Q000276:immunology*; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D014611:Vaccination / Q000662:veterinary; D014765:Viral Vaccines / Q000008:administration & dosage; D014901:West Nile Fever / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D014902:West Nile virus / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D014765:Viral Vaccines