Study On The E2 Gene Nucleotide Sequences Of Classical Swine Fever Virus Field Strains And Their Potential Molecular Difference With The Attenuated Classical Swine Fever Virus Lapinized

E2 genes encoding the major protective antigen region of field classical swine fever virus (CSFV) isolates from Jangsu area were amplified and analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) and restriction fragment length polymorphism (RFLP) respectively. E2 genes of classical swine fever virus filed isolates from Jiangsu area were cloned and sequenced. Comparison and analysis of the nucleotide sequences and the deduced amino sequences among these strains with CSFV C-strain were performed by computer with the DNAstar software. The genetic relationship of the five strains was analyzed by the phylogenetic tree constructed on the base of the data of the E2 gene with computer software. The results showed some substitutions of nucleotides or deduced amino acids scattering along the E2 genes or their encoding proteins compared to those reported.Based on the above results, classical swine fever virus virulent strains, such as SM-strain, Brescia strain, Alfort-187 strain and Esystrup strain all were found to have one recognition sequence of Avaâ… (BmeT110â… )within E2 gene, while attenuated strains, such as GPE strain, CS strain, Riems strain and C-strain were not found. Then restriction fragment length polymorphism (RFLP) was applied to analysis the RT-PCR...