A study of the ability of a TK-negative and gI/gE-negative pseudorabies virus (PRV) mutant inoculated by different routes to protect pigs against PRVinfection

The capacity of a TK-negative (TK-) and gI/gE-negative (gI/gE(-)) pseudorab ies virus (PRV) mutant to protect pigs against Aujeszky's disease carried o ut by experimental infection with a virulent PRV strain, was tested. There were three groups, each of four susceptible pigs which were inoculated twic e by two different schedules. Group 1 received the modified virus by the in tradermal (first inoculation)-intramuscular (second inoculation) routes; gr oup 2 was treated by the intranasal (first inoculation)-intramuscular (seco nd inoculation) routes. The third group was left untreated as the control. All of the pigs were challenged intranasally with a virulent PRV strain and they were subsequently injected with dexamethasone. Two pigs in each group were necropsied on days 5 and 15 after dexamethasone inoculation. The chal lenge exposure resulted in mild clinical signs, increase in growth and a sh orter period of virus shedding in vaccinated pigs, whereas the control grou p showed severe signs of Aujeszky's disease. No difference in the titre of the virulent virus which was excreted by pigs of all three groups, was obse rved and all animals seroconverted. Both the mutant strain and the wild-typ e virus established a latent infection although only the latter was reactiv ated and shed. Slight lesions were observed in target tissues of the vaccin ated animals and no significant differences were detected between the two i noculation schedules.