Isolation and molecular characteristics of a novel recombinant pseudorabies virus strain in Hunan province, China

Pseudorabies (PR), an infectious disease caused by PR virus (PRV), has had a significant impact the development of the swine industry in China. Moreover, the public threat posed by PRV has raised widespread concern, with over 30 documented cases of PRV infection in humans in China. Various vaccines have been developed to prevent and control PR in China, primarily including inactivated vaccines and attenuated live vaccines. However, the extensive use of attenuated live vaccines and the presence of the field PRV strain in pig farm may increase the likelihood of recombination. In this study, we isolated a PRV variant strain (designated HuN-YY) from a piglet that had been immunized with the HB-98 vaccine strain in Hunan province and explored its genetic and biological features. The results showed that the gE, TK and gD genes of HuN-YY exhibited the highest sequence similarity with those of PRV variants, while the gC gene showed high homology with classical PRV strains. In addition, HuN-YY strain exhibited similar replication features compared to those of HB-98 and variant strains. Its pathogenesis in a mouse model was significantly lower than that of the variant strain. Collectively, these results provide clear evidence of genomic recombination of the HuN-YY strain, which will offer guidance for the future prevention and control of PR.