CELLULAR-RESPONSES AND ANTIBODY-RESPONSES TO EQUINE HERPESVIRUS-1 ANDHERPESVIRUS-4 FOLLOWING VACCINATION OF HORSES WITH MODIFIED-LIVE AND INACTIVATED VIRUSES

The ability of monovalent and bivalent equine herpesvirus (EHV) vaccin es to stimulate cellular and antibody responses to EHV-1 and EHV-4 was compared in healthy horses. Comparison of data from lymphocyte blasto genesis tests in which live viruses were used as antigens and that wer e conducted prior to vaccination and after 2 vaccinations revealed tha t houses given modified-live EHV-1 had significant increases in prolif erative responses to EHV-1 (P = 0.03) and EHV-4 (P = 0.04). Responses to EHV-1 and EHV-4 in horses given the inactivated-virus bivalent vacc ine were less; however, significant differences were not noticed when postvaccinal lymphocyte blastogenesis tests were compared between the groups of vaccinees. Interleukin-2 activity was not detected in leukoc yte cultures from either group of vaccinees following stimulation with live EHV-1 or EHV-4; however, interferon activity was found in simila r cultures from both groups of vaccinees. For EHV-4, interferon activi ty in cultures from both groups of vaccinees was significantly (P < 0. 05) greater than that in leukocyte cultures from unvaccinated controls . Both vaccines induced significant (P < 0.05) increases in serum anti bodies that neutralized EHV-1 infectivity. The ELISA for EHV-1 and EHV -4 antibodies revealed that both vaccines induced significant (P < 0.0 5) increases (compared with preinoculation values) in antibodies react ive with these 2 types of EHV. Total serum antibody responses, as meas ured by ELISA, to EHV-1 and EHV-4 were significantly (P < 0.05) higher in horses that received the bivalent inactivated-virus vaccine, compa red with that in horses that received monovalent vaccine. Evaluation o f these data revealed that vaccination with modified-live EHV-1 can st imulate cellular and antibody responses that cross-react with EHV-4.