Screening and Identification of Mimotopes for Lipopolysaccharide Conservative Epitope from Random Phage Display Peptide Library

To screen and identify the mimotopes for lipopolysaccharide(LPS) epitope, a random phage displayed dodecapeptide library was screened with a monoclonal antibody 2B4 specifically against LPS conservative epitope. The positive clones were identified by phage ELISA and competitive inhibition assay by either S.typhi T8 61 LPS or E.coli O111:B4 LPS. After three rounds of biopanning,the clones binding with 2B4 antibody were well enriched with positive rate of 80%. The bindings between 12 of positive phage clones and screening antibody were competitively inhibited by the two kinds of LPS,indicating that the positive clones have similar epitope with LPS. The positive peptide sequences were deduced from the corresponding DNA sequences. There were identical sequences among them. The sequences were GPPQWFFSQPQL (5/12,41 7%),LPQYFWNTATTA (3/12,25%),FPQNHWNVPWAT(2/12,16 6%),HSQSFWNAPLAM and AHPWTHGYFPPL (1/12,8 3%) respectively. The results demonstrate that the peptides screened with 2B4 antibody are mimotopes for LPS conservative epitope.