RESUMEN
In a large herd of pigs where a trial was performed to cure the animals from Aujeszky's disease (AD) by applying to all animals an inactivated vaccine, a post-vaccination antibody response was studied in piglets coming from the sows that were vaccinated several times. When the piglets were vaccinated at the age of eight weeks (the average virus-neutralizing titer (VNT) of colostral antibodies was 1:11.4) and revaccinated at the age of 11 weeks, 73% of the forty-five animals (examined at the age of 17 weeks) did not have any virus-neutralizing (VN) antibodies in the blood serum. After the third vaccination dose (at the age of 17 weeks), 11% of piglets did not have any VN antibodies if they were examined at the age of 22 weeks (the average antibody VNT was 1:15.3). Applying the ELISA procedure, the antibodies were demonstrated in the sera of all piglets after three vaccination doses. Shifting the time intervals of vaccination (at the age of 8, 13 and 19 weeks), the VN antibodies were found out after three vaccination doses in the sera of all piglets examined at the age of 23 weeks (the average VNT was 1:56.4). After three vaccination doses at the age of 12, 17 and 23 weeks, the VN antibodies were also demonstrated in all piglets at the age of 27 weeks (the average VNT was 1:208).