Molecular characterization and phylogenetic analysis of pseudorabies virus variants isolated from Guangdong province of southern China during 2013-2014

Abstract

Outbreaks of pseudorabies (PR) have occurred in southern China since late 2011, resulting in significant economic impacts on the swine industry. To identify the cause of PR outbreaks, especially among vaccinated pigs, 11 pseudorabies virus (PRV) field strains were isolated from Guangdong province during 2013-2014. Their major viral genes (gE, TK, gI, PK, gD, 11K, and 28K) were analyzed in this study. Insertions or deletions were observed in gD, gE, gI and PK genes compared with other PRV isolates from all over the world. Furthermore, sequence alignment showed that insertions in gD and gE were unique molecular characteristics of the new prevalent PRV strains in China. Phylogenetic analysis showed that our isolates were clustered in an independent branch together with other strains isolated from China in recent years, and that they showed a closer genetic relationship with earlier isolates from Asia. Our results suggest that these isolates are novel PRV variants with unique molecular signatures.

Keywords: molecular characterization; phylogenetic analysis; pseudorabies virus.

Fig. 1. Alignment of gE (A), PK (B), gI (C) and gD (D) genes of pseudorabies virus at the nucleotide level. Black box indicates the region of insertion or deletion.

Fig. 2. Phylogenetic trees for gE (A), gI (B), gD (C) and PK (D) genes. Only bootstrap values greater than 50 are shown. Strains marked with black diamonds were isolated in our laboratory during 2013–2014.

Fig. 3. Phylogenetic trees for 11K (A), 28K (B) and TK (C) genes. Only bootstrap values greater than 50 are shown. Strains marked with black diamonds were isolated in our laboratory during 2013–2014.