Genome Characteristics and Evolution of Pseudorabies Virus Strains in Eastern China from 2017 to 2019

Since late 2011, outbreaks of pseudorabies virus (PRV) have occurred in southern China causing major economic losses to the pig industry. We previously reported variant PRV may from recombination in China that could be the source of continued epidemics. Here, we analyzed samples from intensive pig farms in eastern China between 2017 and 2019, and sequenced the main glycoproteins (gB, gC, gD, and gE) to study the evolution characteristics of PRV. Based on the gC gene, we found that PRV variants belong to clade 2 and identified a founder effect by the PRV epidemic process. In addition, we detected inter- and intra-clade recombination, in particular, inter-clade recombination in the gB gene of strains FJ-ZXF and FJ-W2, which were recombinants with clade 1 strains. Specific amino acid changes and positively selected sites possibly associated with functional changes were also observed. The characteristics of PRV emergence in China necessitate continuous monitoring and development of vaccines capable of providing immunity against specific PRV variants.