| In this study the E2 genes of 15 Classical Swine Fever Virus (CSFV) strains isolated from Guangxi (GX) were amplified by reverse transcription polymerase chain reaction (RT-PCR). These E2 gene fragments which contain 1092 base pair in length and encode 364 amino acid residues were cloned and sequenced .Comparison of E2 seqences between 15 GX strains and Hog Cholera Lapinised Virus (HCLV), Shimen strains using DNAStar software was carried out, the result showed that the homology between GX strains and HCLV were 81.5%~82.8% for nucleotide sequence and 82.8%~84.3% for deduced amino acid sequence. The homology between GX strains and Shimen were 87.1%~88.8% for nucleotide sequence and 88.5%~89.9% for deduced amino acid sequence. The nucleotide homology among GX strains were 92.3%~99.9% , and the deduced amino acid homology were 94.8%~100% . Howerer, the homology of nucleotide and deduced amino acid sequence between HCLV and Shimen were 95.9% , 95.3%, respectively. These results demonstrated that the homology among GX strains is high, but between GX strains and reference strains is low. No Cystein residues change on E2 glycoprotein of GX strains had been shown, indicating that E2 glycoprotein of GX strains still remain highly stability. The antigenic domain B and C which related with neutralizing activity ,were variable on the position 724, 725, 729, 734 and 738 of residues. These varieties likely led to antigenic difference among CFSV .Phylogenetic tree among 15 strains of GX and other 19 CSFV strains published were obtained by analyzing nucleotide sequences of E2 gene. These 34 strains are classified into two major Genogroups and a special individual (which agreed with domestic and foreign scholors' conclusions) .Fifteen GX Strains belonged to Genogroup II , but HCLV and Shimen strains belonged to Genogroup I . The Phylogenetic tree revealed that CSFV epidemic strains from GuangXi were significantly genetic divergent from strains Shimen and HCLV in recent years. |
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