Immune Response in Model Animals to Live and Inactivated Vaccine Against Equine Herpesvirus Type-1 Infection

The article presents the results of studying the characteristics of the immune response in model animals - Balb/c mice after immunization with a virus vaccine and an inactivated virus-containing drug against equine herpesviral type-1 infection to control antigenic activity in laboratory conditions. In our experiments, we performed a comparative analysis of the dynamics of the humoral immune response to the inactivated virus and attenuated live virus. The antigenic activity of these vaccines was assessed in ELISA on days 7, 21, 35, 49, 64 and 80 after double immunization of mice with an interval of 14 days. Sera from non-immunized animals served as a negative control. The period of logarithmic increase in antibody titers was observed in all mice on days 7-21 after the second immunization. The highest antibody titers were caused by the live vaccine strain «CB/69». After administration of the preparations, the antibody titer decreased on day 35 for the virus vaccine and on day 49 for the inactivated virus. Thus, the duration of the immune response to the inactivated vaccine was longer than to the virus vaccine. The choice of the concentration ranges of the vaccine preparations for determining the optimal immunizing dose was determined by previous studies, which showed that the virus vaccine in a titer of 5.0 lg TCD 50/sm3 or higher has reactogenic properties for mice, and the maximum titer for the inactivated preparation of 7.0 lg TCD 50/sm3 is limited by the capabilities of virus replication in cell culture. The results of the experiments in the present work showed that the optimal immunizing dose for the «CB/69» vaccine virus is 0.2 x 4.0 lg TCID 50/sm3; for inactivated EHV-1 – 0.2 x 7.0 lg TCD 50/sm3.