Antigen-specific proliferative responses to vesicular stomatitis virus following immunization of cattle with inactive virus.

Peripheral blood mononuclear cells (PBM) from four normal cows with no known exposure to vesicular stomatitis virus (VSV) were cultured with a New Jersey (NJ) serotype (Ogden) VSV that had been UV-irradiated and inactivated. PBM from these animals produced no detectable proliferative response when incubated with varying concentrations of VSV-NJ (Ogden) ranging from 10 ng to 10 micrograms protein/ml. Two of these cows were immunized with an experimental VSV-NJ vaccine and their PBM were tested at various intervals after immunization. PBM tested 14 days after the initial immunization produced readily detectable antigen-specific proliferative responses when cultured with UV-irradiated strains of VSV-NJ. Following a second immunization, lower concentrations of antigen were sufficient to stimulate the proliferative response and the magnitude of the proliferative response was increased. The responsiveness persisted for at least 6 months after these two immunizations. The specificity of the proliferative response was examined by comparing the responses stimulated by one VSV-Ind and four VSV-NJ serotype strains. The PBM from the immunized cows produced proliferative responses that were essentially specific for the VSV-NJ serotype antigens. In dose titrations, the VSV-NJ antigens were 300-1000-fold more effective than was the VSV-Ind antigen. Thus, persistent antigen-specific proliferative responsiveness that is serotype specific can be stimulated by immunizing cattle with an inactivated VSV vaccine.