The immunogenic properties of a series of
glycoprotein preparations are compared using inactivated conventional
vaccines as reference. Serological response and protective efficacy of vaccination of mice and pigs are evaluated for
glycoprotein immunogens obtained from various sources. BHK-21 cell cultures were infected with Aujeszky's disease virus and used as antigenic source.
Glycoproteins were obtained from (i) the whole culture (ii) the cell sediment and (iii) the clarified supernatant. Both in pigs and in mice, protection was greater with
glycoproteins purified from infected-cell membranes than with viral mature particle
glycoproteins. The specific profiles of humoral responses were basically identical regardless of the source of
glycoprotein. Bartha strain, one of the gI- strains most commonly used as an
attenuated vaccine, was also used as a
glycoprotein source. Immunogens obtained from this strain were protective in challenge trials with the virulent E-974 strain of the Aujeszky's disease virus.
Glycoproteins did not induce detectable delayed type
hypersensitivity in mice but conferred greater protection than particulate
antigens (which, conversely, did induce a detectable delayed type
hypersensitivity reaction). Until the recent proposal of the potency criterion delta 7, no objective method was available to evaluate the degree of protection conferred by
Aujeszky's disease vaccines. In this study, we thus used the protection index, a quantitative parameter designed to evaluate potency of
vaccines against Aujeszky's disease virus.