Protective effect of glycoprotein gC-rich antigen against pseudorabies virus.

A trial vaccine containing pseudorabies virus (PRV) glycoprotein gC as the main component showed excellent protection against virulent virus infection in pigs. Glycoprotein gC-rich antigen was prepared by heparin affinity chromatography from PRV-infected cell lysates. The preparations were mixed with mineral oil adjuvant as a water-in-oil emulsion. Six-week-old pigs were immunized twice at two-week intervals with trial vaccines containing 128,000, 12,800 and 1,280 HA units per dose of gC antigen. They were then challenged with a virulent PRV at day 7 after the final immunization. Neutralizing (NT) antibodies were produced with increase of antibody titers after challenge. Pigs immunized with 128,000 HA units per dose of gC survived and showed no virus shedding during the 2-week experimental period after the challenge. The role of cell-mediated immunity was examined using BALB/c mice, and induction of gC-specific cytotoxic T lymphocytes (CTLs) was detected by 51Cr release assay. From these results with mice, it is inferred that cell-mediated immunity, especially CTL, may play an important role in the effectiveness of our trial vaccine in addition to humoral immunity.