Oronasal challenge of fattening pigs after vaccination with an inactivated Aujeszky's disease vaccine.

Groups of pigs from vaccinated and unvaccinated sows were vaccinated once or twice between the ages of eight and 20 weeks with a commercial inactivated, oil adjuvanted Aujeszky's disease virus vaccine. Pigs were challenged by the oronasal route when 22 to 27 weeks old. Pigs from unvaccinated sows developed neutralising antibodies after vaccination but no seroconversion was detected in eight-week-old pigs or in 80 per cent of 15-week-old pigs from vaccinated sows. Challenge resulted in severe disease and weight loss in control pigs. In vaccinated animals the duration and severity of clinical signs and the amount of weight lost decreased with increasing serum neutralisation titres. The results indicate that parenteral vaccination at weaning with the vaccine described will not protect pigs at slaughter age against infection and disease, particularly if they were born from seropositive mothers.