Expression of H3N2 Subtype Swine Influenza Virus (SIV) Hemagglutinin 1 (HA1) and Screening out a New Epitope with Phage Displayed Library

摘要

Swine influenza virus (SIV), subtype H3N2, is a newly emerged re-assorted influenza virus in swine. To development new vaccine with high efficiency, effective epitopes was to be identified. Since hemagglutinin (HA) is the most important surface protein of all influenza viruses including SIV, HA1, fragment of HA, was cloned with RT-PCR, and then overexpressed in Escherichia coli. Recombined HA1 was purified and inoculating New Zealand rabbit. The anti-serum from immunized rabbit was isolated and IgG purified which was coated in 96-wells for biopanning with dodeca-peptide phage library. After four rounds bioscanning, 20 eluted single phage colonies were selected, and Sandwich and competitive inhibition ELISA were performed to identify the specificity of the colonies. The phages were amplified and DNA templates were extracted for sequencing. Subsequently their amino acid sequences were deduced. The results show all of the fourth round eluted phage can bind with the specific IgG. Alignment with the 9 HA1 of H3N2 strains, eight amino acid residues were conservative and the homological model-building analogy graph shows that the 8 residues are adjacent in space conformation. The results indicate the space adjacent 8 amino acid residues may be a new space conformation epitope in HA of subtype H3N2 SIV.