Assessment of antigenic difference of equine influenza virus strains by challenge study in horses

Influenza Other Respir Viruses. 2016 Nov;10(6):536-539. doi: 10.1111/irv.12418. Epub 2016 Aug 9.


We previously reported that horse antiserum against the Japanese equine influenza vaccine virus, A/equine/La Plata/1993 (LP93) exhibited reduced cross-neutralization against some Florida sublineage Clade (Fc) 2 viruses, for example, A/equine/Carlow/2011 (CL11). As a result, Japanese vaccine manufacturers will replace LP93 with A/equine/Yokohama/aq13/2010 (Y10, Fc2). To assess the benefit of updating the vaccine, five horses vaccinated with inactivated Y10 vaccine and five vaccinated with inactivated LP93 were challenged by exposure to a nebulized aerosol of CL11. The durations of pyrexia (≥38.5°C) and other adverse clinical symptoms experienced by the Y10 group were significantly shorter than those of the LP93 group.

Keywords: H3N8; challenge study; equine influenza; inactivated whole vaccine.

MeSH terms

  • Animals
  • Antibodies, Viral / blood*
  • Antibodies, Viral / immunology
  • Antigens, Viral / genetics
  • Antigens, Viral / immunology*
  • Horse Diseases / immunology*
  • Horse Diseases / virology
  • Horses
  • Influenza A Virus, H3N8 Subtype / immunology*
  • Influenza A virus / immunology
  • Influenza Vaccines / immunology*
  • Orthomyxoviridae Infections / immunology
  • Orthomyxoviridae Infections / veterinary*
  • Orthomyxoviridae Infections / virology
  • Vaccines, Inactivated / administration & dosage
  • Vaccines, Inactivated / immunology


  • Antibodies, Viral
  • Antigens, Viral
  • Influenza Vaccines
  • Vaccines, Inactivated