Evaluation of humoral and antigen-specific T-cell responses after vaccination of pigs against pseudorabies in the presence of maternal antibodies.

In this study the influence of maternal immunity against pseudorabies virus (PRV) on the development of humoral and T-cell mediated immune (CMI) responses was investigated under the experimental condition. Pigs born to immune sows were vaccinated with gE-deleted vaccine according to five different schedules. Peripheral blood mononuclear cells (PBMC), collected after vaccination, were used for PRV-induced lymphocyte proliferation assay (LPA). Antibodies to the gB and gE of PRV in serum were determined using ELISA kits. Maternally derived antibodies (MDA) in the serum of unvaccinated piglets born to immune sows were above the level considered to be positive until about 10-11 weeks of life. The active humoral as well as CMI responses was the highest in group vaccinated at 10 and 14 weeks of age. The results of this study suggest that MDA may disturb or even block development of active humoral response. Early priming of T-cells with attenuated gE-deleted PRV vaccine in the presence of MDA could be successful, but obtaining a long-term cellular immunity at least one booster is required.