[Objective] A total of 260 swine samples of dead or sick pigs collected from 7 provinces （municipalities） Jiangsu, Anhui, Shanghai, Shandong, Zhejiang, Fujian and Jiangxi of China during 2008-2010 were detected for ...
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[Objective] A total of 260 swine samples of dead or sick pigs collected from 7 provinces （municipalities） Jiangsu, Anhui, Shanghai, Shandong, Zhejiang, Fujian and Jiangxi of China during 2008-2010 were detected for porcine reproductive and respiratory syndrome virus （PRRSV）. And the ORF5 genes of some isolates were amplified and sequenced for understanding the molecule epidemiology and the genetic evolution of PRRSV in East China. [Method] Using RT-PCR method, PRRSV was detected by RT-PCR from samples. The complete ORF5 genes of 36 PRRSV positive samples was amplified, sequenced and analyzed with other 15 strains available on GenBank. [Result] PRRSV was detected in 118/260 of the clinical samples, with a positive rate was 45.4%. Sequence analysis showed that the 36 isolates of this study belonged to the North American-type PRRSV strains and were closely related to the highly pathogenic PRRSV （HP-PRRSV） with 94.6%-100% amino acid sequence identities. The sequence analysis combined with the phylogenetic analysis indicated that all these North American-type PRRSV strains in East China were further divided into five subgenotypes, subgenotype Ⅲ showed closer identity with HPPRRSV; almost all subgenotypes were found to be variable in the primary neutralizing epitope; subgenotypes Ⅲ and IV had more glycosylation sites than others. Although these 36 isolates were collected from different provinces in East China, there were no obvious relations between the distribution of PRRSV and the region. [Conclusion] The PRRSV infection was widespread and HP-PRRSV was the popular strain in East China during 2008-2010. However some different genetic characteristics appeared in the genomes, the genetic evolution was relatively stable. There exists a cross-cutting phenomenon on the genetic relationship of PRRSV isolates obtained from different provinces. Subgenotypes IV and V only appeared in some provinces, but the distribution of PRRSV did not show apparent geographical characteristics.
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