Authors : Peng Zhao, Cheng-Tai Ma and Zhi-Zhong Cui
Abstract: To study the quasispecies diversity and mutations of highly pathogenic porcine reproductive and respiratory syndrome virus emerged in 2006 in China, the ORF5 gene of a wild HP-PRRSV strain SD0612 was amplified and the amplified product was cloned into T vector, all positive clones were sequenced and analyzed with DNA Star software. To exclude sequencing errors, another very conservative gene ORF6 with the similar product length to ORF5 gene was amplified, cloned and sequenced as above. About 60 positive clones of ORF5 gene were obtained, sequenced and analyzed and their nucleic acid sequence homology ranging from 97.7-100%, a total of 78 base mutants between them were found. Among these 60 sequence 17 sequence was quite the same and be determined as the sequence of advantage quasispecies which account for the magerority of SD0612. For the conservative ORF6 gene, 54 positive clones were obtained and their nucleic acid sequence homology ranging from 99.2-100%, among these 54 sequences 46 sequences was quite the same, a total of 8 base mutants were found between them. The GP5 sequence for advantages quasispecies of SD0612 was also compared with other reference GP5 sequence of 20 highly pathogenic PRRSV mutants and they shared only 93.5-98.5% homology, total 23 mutation points between them was found and some mutations located in the epitopes. This study indicate the quasispecies diversity of SD0612 can be indicated by the sequence diversity of ORF5 gene, the mutations between different HP-PRRSV mutants is also great although they have the same deletions in NSP2 gene.
Peng Zhao, Cheng-Tai Ma and Zhi-Zhong Cui, 2012. Analysis of Quasispecies Diversity and Mutations for Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus in China Based on ORF5 Genes. Journal of Animal and Veterinary Advances, 11: 2741-2746.