Identification of host cell binding peptide from an overlapping peptide library for inhibition of classical swine fever virus infection.

The envelope proteins of classical swine fever virus (CSFV) mediate the binding of CSFV to cell surface molecules and allow CSFV subsequent to enter host cells. However, the proteins binding to host cells and their binding sequences are uncertain. The results showed that the protein E1, E2, and Erns were displayed on the surfaces of T7 phages. The E2 and Erns phage clones showed high binding affinity to host cells, in which the E2 phage clone interacted more specifically with host cells than with other cells, while the Erns phage clone interacted with all tested cells. A 30-mer phage displaying peptide library was constructed and screened against immobilized host cells, in which each peptide was overlapped 10aa to another peptide and spanned all amino acid sequences of Erns and E2. Fifty-eight clones with specific binding to host cells were isolated. Amino acid sequence analyses for two phage clones (P2 and P6) demonstrated the strongest binding positions were at 101-130 (S2) in Erns, and 141-170 (S6) in E2, respectively. The synthetic peptides (S2 and S6) could inhibit the binding of phage clones (P2 and P6) and CSFV to cell. About 86.74 and 74.24% inhibition rates of CSFV infection were achieved at 55 μM of the synthetic peptides S2 and S6. The results also indicated that the S2 (LAEGPPVKECAVTCRYDKDADINVVTQARN) and S6 (AVSPTTLRTEVVKTFRRDKPFPHRMDCVTT) from CSFV were host cell binding peptides, and both of them had potential for research of CSFV entering host cells.