Efficacy of a mixed glycoprotein vaccine against pseudorabies in pregnant sows

A pseudorabies virus (PRV) glycoprotein-mixed vaccine was prepared by heparin-affinity chromatography from PRV-infected PK-15 cell lysates. In our previous study, the trial vaccine was induced protection with suppression of virus shedding in one-month-old pigs and generation of cytotoxic T lymphocyte (CTL) response in mice. In this study, the effect of the trial vaccine on suppression of both virus shedding and reproductive failure in pregnant sows was examined. Three sows were vaccinated twice until one week before mating. Each of them was infected intranasally with 10(6) TCID50 of PRV on day 28, 54, or 85 after mating, respectively. Three other sows were also mated and challenged at the same time as the respective control. The vaccinated sows produced virus-neutralizing antibodies. Sows with high level of VN antibody lowered the level and period of virus shedding after challenge. The maximum level of shed-virus titers in vaccinated sows were 10(1.25) to 10(3) times lower than controls. Vaccinated sows shed virus for 1 or 5 days, while controls shed for 8, 9, or 12 days. No abortion or stillbirth was observed in vaccinated sows during pregnancy. On the other hand, control sow challenged at a late stage of pregnancy showed abortion and stillbirth. The results obtained here indicate that our trial vaccine is effective to prevent reproductive failure by pseudorabies virus.