COMPARATIVE EFFICACY OF 3 DOSES OF THE GENETICALLY ENGINEERED AUJESZKYS DISEASE VIRUS-VACCINE STRAIN 783 IN PIGS WITH MATERNAL ANTIBODIES

Pigs with low levels of maternally derived antibodies were vaccinated twice intramuscularly with 10(5), 10(5.5), or 10(6) plaque forming units (p.f.u.) of the genetically engineered Aujeszky's disease virus (ADV) vaccine strain 783. Strain 783 has deletions in genes encoding glycoprotein gI and thymidine kinase. All vaccinated pigs showed a high level of protection against clinical disease after challenge infection with virulent ADV. Vaccination also reduced virus excretion. The daily mean virus excretion and the mean number of days with virus excretion, fever, mild clinical signs, and growth retardation were higher in pigs vaccinated with 10(5) than in pigs vaccinated with 10(5.5) or 10(6) p.f.u. of strain 783.