Identification Of The Ligand Epitope Of The Classical Swine Fever Virus

Classical swine fever (CSF) is a highly contagious and fatal disease of swine, which is caused by Classical swine fever virus (CSFV), a member of the genus Pestivirus of the family Flaviviridae. Erns, E1 and E2 are the chief structrural proteins of CSFV and relevant to adsorption and invasion of target cell. For identification of the ligand epitope binding with target cells of CSFV, we designed and synthesized ten peptides according to the amino acid sequence of the glycoprotein Erns E1 and E2 of the CSFV by using bioinformatics technique. Porcine kidney 15 (PK-15) cells were used as the target cell. Peptide binding with PK-15 cell and blocked binding assays were used for screening and identification of ligand epitope of CSFV. Furthermor, CSFV infection inhibiting experiment was applyed to identify the function of the epitope peptide. The results indicate that the polypeptide SE24 in E2 glycoprotein of CSFV can bind with PK-15 cells effectively at the concentration of 0.2mmol/L, 0.1mmol/L, 0.05mmol/L and 0.025mmol/L. Blocking assay showes that the epitope peptide SE24 can inhibite the CSFV infecting PK15 cells, in which the precentage of positive cells and the mean fluorescence intensity reduced by 11.6% and 3.07, respectively. These results demonstrate that peptide SE24 is a ligand epitope of the CSFV, and its amino acid sequence is VHASDERLGPMPCRPKEIGSSAGPVRKTSCTFNYAKTGKNKYYEPRDSYF on the glycoprotein E2. It is suggested that the ligand epitope peptide SE24 has the function of infection inhibiting with dose dependent according to the infection rate of CSFV decreased while the concentration of the ploypeptide SE24 increased. And the infection of CSFV is inhibited completely at the concentration of 0.2mmol/L of the ploypeptide SE24.