Complete Genomic Sequence Analysis Of Epidemic PCV2 Strains Isolated From Fujian Province

PURPOSE:To investigate the genetype and mutation of seven PCV2 strains prevailing in Fujian province in recent years to get more information about epidemiology of the disease,and to provide scientific basis for investigating the construction function and mutation rule of the gene and the biomolecular characteristics of PCV2,and for developing effective immune preparation.The complete genome of the seven PCV2 isolates from different pig farms in different area of Fujian province was compared with published genomes of PCV2 isolates in GenBank and the genetic relativity and molecular differences were analysed among PCV2 strains.METHOD:According to the published gene sequence of PCV2 in GenBank,two pairs of specific primers were designed and synthesized to amplify the complete genome of the seven PCV2 strains.These amplified productions were cloned into pMD 18-T easy vector and sequenced.These sequences of the complete genome of the seven PCV2 isolates were compared with published genomes of seventeen PCV2 isolates and two PCV1 isolates in GenBank by DNAstar software.and a phylogenetic tree of the PCV2 strains was drawn.Nucleotide sequence and amino acid identify of ORF1 gene and ORF2 gene of the seven isolates were compared with published genomes of PCV2 isolates in GenBank,and the mutation locus were compared and analyzed as well.Moreover,hydrophilic property and epitope of ORF2 genes of the seven isolates were analyzed.RESULT:(1)the genomes of the seven PCV2 isolates were 1767bp in length. (2)There was a 98.4%-99.5%homology of the complete genomic nucleotides and 98.1%-99.7%homology of nucleotide sequence and amino acid of the ORF1 genes among the seven isolates.The ORF2 genes of the seven isolates homologous rate was 98.9%-99.7%,and the amino acid homologous rate was 97.9%-99.6%.(3) Compared with other reference PCV2 strains in GenBank,the homology of the complete genomic nucleotides among the PCV2 strains was 94.7%-99.5%;the homology ofnucleotide sequence and amino acid of the ORF1 genes and ORF2 genes were 95.9%-99.7%and 95.9%-99.7%;91.1%-99.7%and 85%-100% respectively.CONCLUSION:(1)Complete genomes of the seven PCV2 strains isolates from Fujian provine were high homology and no significantly differences were observed. (2)The genes of ORF1 of the seven PCV2 strains were also high homology and were relatively conservative,and their heterogeneity was very low.(3)greater mutation was observed in ORF2 which was provided with highly hydrophilic property and immunogenicity.