Sequences Analysis of Virulence Associated Genes gE and TK of Pseudorabies Virus Strain BJ/YT

To analyze the molecular characterization and evolutionary relationship of the virulence associated genes of the BJ/YT strain which was isolated from a Yorkshire Terrier in Beijing in 2012. The results revealed that the homologies of the gE gene nucleotide sequences and amino acid sequences were 98.9% to 100.0% and 98.3% to 100.0%, respectively; meanwhile, the homologies of the TK gene nucleotide sequences and amino acid sequence were 99.2% to 99.9% and 99.0% to 100.0%, respectively. The phylogenetic tree based on gE gene showed that BJ/YT and the strains isolated from Hebei province could be grouped into a relatively independent branch, and all of them shared a high homology. Besides, a concordant mutation site was presented. Few mutation sites in gE and TK amino acid sequences were observed when compared with other referenced sequences. But those sites were not located in the main domains or antigenic epitope regions. Therefore, from the view of molecular epidemiology, it was likely that the BJ/YT isolate was the main circulating strain in Beijing and its surrounding area the last few years. However, the variations of gE and TK genes did not have obvious effects on the virulence of the epidemic strain during this period.