Led by Hongxuan He’s research group at Institute of Zoology, Chinese Academy of Sciences, seven PRRSV field isolates Shijiazhuang city of Hebei province in China were analyzed on the molecular and biological characteristics based on five genes (GP2, GP3, GP4, GP5 and NSP2). Phylogenetic analyses based on the nucleotide sequence of the ORF2-5 and NSP2 showed that the seven Chinese isolates belonged to the same genetic subgroup and were related to the North American PRRSV genotype. Comparative analysis with the relevant sequences of another Chinese isolate (BJ-4) and North American (VR2332 and MLV) viruses revealed that these isolates have 80.8-92.9% homology with VR-2332, and 81.3-98.8% identity with MLV and 80.7-92.9% with BJ-4. All Nsp2 nonstructural protein of these seven isolates exhibited variations (a 29 amino acids deletion) in comparison with other North American PRRSV isolates. Therefore, these isolates were novel strain with unique amino acid composition. However, they all share more than 97% identity with other highly pathogenic Chinese PRRSV strains. Additionally, there are extensive amino acid (aa) mutations in the GP5 protein and the Nsp2 protein when compared with the previous isolates. These results might be useful to study the genetic diversity of PRRSV in China and to track the infection sources as well as for vaccines development.

This work was supported by grants from: Hi-Tech Research and development program of China (863, 2007AA100606), National Science and Technology Ministry(ID:2009BAI83B01) and The National Key Basic Research and Development Program of China (973, 2007BC109103).

Chengmin Wang, Bin Wu, Said Amer, Jing Luo, Hongmei Zhang, Yunhai Guo, Guoying Dong, Baohua Zhaoand Hongxuan He. Phylogenetic analysis and molecular characteristics of seven variant Chinese field isolates of PRRSV. BMC Microbiol. 2010 May 20; 10:146.