A gD&gC-substituted pseudorabies virus vaccine strain provides complete clinical protection and is helpful to prevent virus shedding against challenge by a Chinese pseudorabies variant

BackgroundSince 2011, pseudorabies caused by a variant PRV has re-emerged in many Chinese Bartha-K61-vaccinated pig farms. An efficacious vaccine is necessary to control this disease. We described the construction of a gD&gC-substituted pseudorabies virus (PRV B-gD&gC(S)) from the Bartha-K61 (as backbone) and AH02LA strain (as template for gD and gC genes) through bacterial artificial chromosome (BAC) technology using homologous recombination. The growth kinetics of PRV B-gD&gC(S) was compared with Bartha-K61. Its safety was evaluated in 28-day-old piglets. Protection efficacy was tested in piglets by lethal challenge with AH02LA at 7days post vaccination, including body temperature, clinical symptoms, virus shedding, mortality rate, and lung lesions.ResultsThe results showed that a BAC clone of Bartha-K61 and a B-gD&gC(S) clone were successfully generated. The growth kinetics of PRV B-gD&gC(S) strain on ST (Swine testicular) cells was similar to that of the Bartha-K61 strain. No piglets inoculated intramuscularly with PRV B-gD&gC(S) strain exhibited any clinical symptoms or virus shedding. After AH02LA challenge, all piglets in PRV B-gD&gC(S) and Bartha-K61 groups (n=5 each) survived without exhibiting any clinical symptoms and high body temperature. More importantly, PRV B-gD&gC(S) strain completely prevented virus shedding in 2 piglets and reduced virus shedding post challenge in the other 3 piglets as compared with Bartha-K61 group.ConclusionsOur results suggest that PRV B-gD&gC(S) strain is a promising vaccine candidate for the effective control of current severe epidemic pseudorabies in China.