Study of homologous and heterologous antibody response in California horses vaccinated with attenuated Venezuelan equine encephalomyelitis vaccine (strain TC-83).
Of 359 horses vaccinated with attenuated Venezuelan equine encephalomyelitis (VEE) vaccine (strain TC-83), 87% developed hemagglutination-inhibition (HI) antibodies to VEE virus within 1 month. Blood from a subsample of 101 of the 359 horses was obtained over a 1-year period. Within 1 month after vaccination, 84% of the 101 horses had developed VEE HI antibodies, 87% had developed VEE-neutralizing (Nt) antibodies, and 78% had developed VEE complement-fixing (CF) antibodies. One year after vaccination, 58% of the horses had VEE HI antibodies and 73% had VEE Nt antibodies. The percentage of horses with VEE CF antibody titers dropped to a low level (46%) within 6 months after vaccination, and most horses were seronegative for VEE CF antibodies 1 year after vaccination. The presence of antibodies to heterologous (western equine or eastern equine encephalomyelitis, or both) alphaviruses suppressed VEE antibody formation in horses vaccinated with TC-83 vaccine. However, the proportion of horses that developed VEE antibodies exceeded levels that generally were believed adequate to suppress a VEE epizootic in a population. There was an 88% correlation between the HI and Nt tests for VEE antibodies.
D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis*; D000917:Antibody Formation; D002140:California; D003168:Complement Fixation Tests; D004663:Encephalitis Virus, Eastern Equine / Q000276:immunology; D004666:Encephalitis Virus, Venezuelan Equine / Q000276:immunology*; D004667:Encephalitis Virus, Western Equine / Q000276:immunology; D006385:Hemagglutination Inhibition Tests; D006736:Horses / Q000276:immunology*; D009500:Neutralization Tests; D014611:Vaccination / Q000662:veterinary*; D014613:Vaccines, Attenuated; D014765:Viral Vaccines
D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines