Background and Aim: The Aujeszky's disease, also known as Pseudorabies, remains one of the most problematic fulminant diseases in domestic animals, affecting the central nervous system. The study aimed to investigate the effect of an inactivated vaccine against Aujeszky's disease based on "Kordai" virus strain.

Materials and Methods: To test the inactivation of the "Kordai" strain (grown by the roller method in VNK-21/13 cell culture with an infectious titer of at least 7.5 lg TCD₅₀/ml) which is causative of Aujeszky's disease, next-generation teotropin and propolis preparations were used in concentrations of 0.1%, 0.08%, and 0.04%.

Results: As a result of comparative studies on the optimization of parameters for inactivating the "Kordai" virus strain, it was established that teotropin is a more effective inactivant than propolis. At the same time, the optimal final concentration of teotropin for inactivation was 0.1%, along with a reaction medium temperature of 37°C, pH of 7.4-7.6, and duration of inactivation of 14 h. The titer of virus-neutralizing activity (VNA) of antibodies at the pH (neutralization reactions) in vaccinated sheep of 10-12 months of age was 7.5±0.3, Ig TCID₅₀/ml (tissue culture infectious dose 50%), and 3.5±0.3 in the cell culture VNK-21/13 (culture of Syrian hamster kidney cells).

Conclusion: To determine colostral immunity in newborn lambs, the method of metabolic status correction was used to vaccinate lambs obtained from immune sheep 4 months after birth. The results showed that lambs obtained from immune sheep had high VNA titers. A sustained immune response in vaccinated animals was obtained after double vaccination.

Keywords: adjuvant, Aujeszky's disease virus, colostral immunity, immunogenicity, strain "Kordai."