| In this study the E2 genes of 6 strains of Classical Swine Fever Virus (CSFV) isolated from healthy pig tonsils and abortive embryos in Guangxi (GX) were amplified by reverse n-transcription polymerase chain reaction (RT-nPCR). These E2 gene fragments which contain 1119 nucleotides in length and encoding 373 amino acid residues were cloned and sequenced.Comparison of E2 seqences between 6 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 92.5%~96.6% for nucleotide sequence and 90.0%~98.4% for deduced amino acid sequence. The homology between GX strains and Shimen were 89.8%~93.9% for nucleotide sequence and 86.3%~94.1% for deduced amino acid sequence. The nucleotide homology among GX strains were 93.1~99.6% , and the deduced amino acid homology were 86.3-99.2% . Howerer, the homology of nucleotide and deduced amino acid sequence between HCLV and Shimen were 95.5% and 94.6%, respectively. These results demonstrated that the homology among GXstrains is high, but between GX strains and reference strains Shimen is low, while between GX strains and HCLV, the homology is high. 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 change on the position 721 and 724 of residues. These varieties likely led to antigenic variance among CFSV .Phylogenetic tree among 6 strains of GX and other CSFV strains published were obtained by analyzing nucleotide sequences of E2 gene. These strains were classified into two major Genogroups . Six GX Strains belonged to Genogroup I, and HCLV and Shimen strains belonged to Genogroup I, too. The Phylogenetic tree revealed that CSFV strains from GX were not significantly genetic divergent from strains Shimen and HCLV in recent years.
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