Wang Feng-Xue, Yang Bo-Chao, Wen Yong-Jun , Liu Zhun , Leng Xue et al
Porcine reproductive and respiratory syndrome (PRRS) is an economically important disease in swine producing area. PRRSV vaccine strain TJM had been proved to have low virulence in swine. To investigate the genomic characteristics of TJM strain, the full-length nucleotide sequence was obtained and analyzed. It contains 14 960 nucleotides in length. The nucleotide variations and amino acid substitutions were randomly distributed in the genome comparing to its parental TJ strain, but mainly occurred on the nonstructural protein genes Nsp1, Nsp2, Nsp3, Nsp9 and Nsp10, as well as on the structural protein gene ORF7. The most notable variation is the 360 nucleotides deletion exhibited in the Nsp2 gene. The novel deletion in Nsp2 resulted in altered protein structure. The genomic sequence of TJM was also compared with that of two US isolates (prototypic VR-2332 strain and virulent isolate P129) and eight Chinese isolates (previous isolates CH-1a, BJ-4, HN1, HB-2(sh) 2002, MN184C, and newly highly pathogenic isolates JX143 and GDQY2). TJM and the highly pathogenic strains belong to one group on phylogenetic relationship, although TJM has a low virulence. The 120- amino acid deletion downstream the 30-amino acid deletion region is unique to the attenuated TJM strain and applicated for discriminating the vaccine TJM from other virulent PRRSV.
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