Genetic Analyses Of CSFV E2Gene In Several Rigions Of China And Complete Gene Of Isolate HeN2F16

Classical swine fever (CSF) was caused by Classical swine fever Virus (CSFV), which belonged in the genus Pestivirus in the family Flaviviridae. Acute CSF had got to lead to many serious discusses, as high fever, severe depression, anorexia, diarrhea, multiple superficial and internal hemorrhages, central nervous disorders, vertical transmission and high morbidity and mortality. CSFV had the cause of the severe economical impact and were notifiabled by the Office International des Epizootics (OIE). In China, CSFV had led to serious effects and losses several years before. However, CSFV was not cleaned up in many farms of china, and sometimes it was going to lead to more latent CSFV infection or secondary infection. The morbidity of CSFV has recently keeping between10%～15%, although most farms of China used the vaccine (HCLV) made in china.To investigate the variation of CSFV in China and samples which were collected in2012to2013from12provinces were positive in CSFV detected by RT-nested PCR and sequenced. To gain insight into the molecular epidemiology of CSFV in China with167isolates and analyzing that the N-terminal fragment of E2gene, which was the hypervariable region of E2. The result revealed that all of these167isolates belonged to subgenotype1.1and2.1.There were59isolates (35.3%of total) classified in Subgenotype1.1, and108isolates (64.7%of total) classified in Subgenotype2.1, and none of isolates were classified in Subgenotype2.2or Subgenotype2.3. All viruses of Subgenotype1.1were closed to HCLV and more diversity with Shim en strain, and it proved that Shimen strain had been not more popular than before. So they were presumed to be lentogenic strains. Most of viruses belonged to2.1. The isolates of2.1b were more prevalent than others and the viruses of2.1c had a tendency to be popular.According to the analyzing of homology, nucleotide sequence identity between Subgenotypes1.1which were isolated in2012to2013and the vaccine (HCLV) was97.4%-99.5%, which nearer than Shimen (94.7%～95.3%), and the identity of amino acid sequences was96.6%～100.0%. The average nucleotide homology between2.1b and2.1c was86.7%. The nucleotide sequence identity was79.4%～83.6%between Subgenotypes2.1b and HCLV, and81.0%～81.5%between2.1c and HCLV. The different of amino acid sequences was84.1%～87.3%between Subgenotypes2.1b and HCLV. and85.1%～88.9%between2.1c and HCLV.Analyzing with B/C major pep-tide binding region of E2gene which was gain show isolates of subgenotype1.1were not more variation than HCLV. There were many changings of B/C gene, and most of them collect on two locuses (720aa and721aa). The locuse (736aa) was more different between2.1and HCLV (subgenotype1.1). and10locuses had changed on B/C gene (720aa,723aa,725aa.729aa.734aa.736aa.738aa..745aa,761aa and777aa).Thereinto, evasion locuses of immune on B/C gene (729aa and736aa) and one antigen epitope of lymphatic B cell (777aa) had also changed.Depending on CSFV complete gene on GenBank (NCBI), primers for degenerate PCR were disgined with Primer Premier6and Oligo7to amplification of HeN2F16. Compare with sequence of isolate HeN2F16on BLAST show the most nearly nucleotide sequence identity was isolate GXWZ02. It was demonstrate there was traditional pandemic strain (2.1b). Acoording to SWISS-MODEL online, the protein structure of HeN2F16E2complete gene was predicted. And there was raised structure on the surface and it was consist of729aa and736aa in ORF. This structure was different from the same position of HCLV, and it should be going to research whether it has more effects by the changing of structure.