Vaccines against Aujeszky's disease: comparison of efficacy, DNA fingerprints and antibody response to glycoprotein I.

The efficacy of two inactivated and three attenuated Aujeszky's disease virus (ADV) vaccines was compared in pigs in a standardised test. After vaccination, excretion of attenuated vaccine viruses was not detected. All vaccines were capable of preventing mortality, but none conferred complete protection against challenge with a virulent strain of ADV 3 months after the first vaccination. After a single vaccination, no large differences in vaccine efficacy were observed. Revaccination markedly enhanced protection; however, with one vaccine this was not the case. The two inactivated vaccines induced quite different levels of neutralising antibodies. Two vaccine viruses had a wild-type DNA fingerprint and gave rise to an antibody response to glycoprotein I (gI) of ADV. The three remaining vaccines carried a deletion in the unique short region of the genome. Two of them failed to induce gI-antibody in pigs. Pigs given the third 'deleted' vaccine did not respond uniformly of gI. With regard to control of Aujeszky's disease, efficacious vaccines with a 'serological' marker may be preferred in the future.