Immunity of Pigs Vaccinated by Live or Inactivated Aujeszky Vaccines Against Experimental Infection

Abstract

Methods used in Aujeszky's disease (AD) control depend on the stage of its extension, the economic losses caused and the methods of management. Serological control and corresponding elimination measures are sufficient in the case of sporadic infection, but where infection is enzootic in an area and endemic infection exists on pig farms with large scale production one must apply methods of specific prophylaxis. For this purpose live vaccines have been used in the countries of middle and east Europe for two decades (2, 3, 4, 8, 11, 22,37). Attempts to eliminate the shortcomings resulting from the use of live vaccines and inactivated vaccines against AD have made it possible to provide the vaccinated pigs with a good protection against natural as well as experimental infections (5, 7, 14,29). Immunity stimulated by vaccination with live and inactivated vaccines does not preventin the case of contact with infectioncolonization of mucous membranes of the respiratory tract and virus excretion (6, 9, 10, 12, 18,30).In our laboratory, besides the derivation of several lines from the Bucarest strain, known to have differing residual virulence and used for preparation of live vaccines for various species of animals (31, 36), an inactivated vaccine with an oil adjuvant has been prepared and found to possess a good immunizing effect (38). The aim of the experiments discussed in this paper was to find whether there are differences in the clinical and biological protection of pigs vaccinated by live and inactivated vaccines and thus in the efficiency of the immunity stimulated by the two types of preparations to eliminate the virulent virus from the population of vaccinated pigs. Material and MethodsVaccines. Live lyophilized SUIVAK vaccine from the Buk-TK/650 strain was used (33). After rehydration in an equivalent volume of a solvent, 2 ml. were applied s. c., which re-U.S.