ABSTRACT
Random peptide libraries displayed by bacteriophage T7 and M13 were employed to identify mimotopes from 4 monoclonal antibodies (MAbs) specific to Burkholderia pseudomallei. Insert DNA sequences of bound phages selected from four rounds of panning with each MAb revealed peptide sequences corresponding to B. pseudomallei K96243 hypothetical protein BPSL2046, hypothetical protein BpseP_02000035, B. pseudomallei K96243 hypothetical protein BPSS0784, B. pseudomallei 1710b hypothetical protein BURPS1710b_1104, and B. cenocepacia H12424 TonB-dependent siderophore receptor, all located at the outer membrane. The immune responses from all selected phagotopes were significantly higher than that of lipopolysaccharide. The study demonstrates the feasibility of identifying mimotopes through screening of phage-displayed random peptide libraries with B. pseudomallei MAbs.
Subject(s)
Amino Acid Sequence , Animals , Antibodies, Bacterial/immunology , Antibodies, Monoclonal/genetics , Antibody Specificity , Antigens, Bacterial/immunology , Bacterial Vaccines/immunology , Bacteriophage M13/genetics , Bacteriophage T3/genetics , Base Sequence , Burkholderia pseudomallei/immunology , Enzyme-Linked Immunosorbent Assay , Epitopes/genetics , Melioidosis/immunology , Mice , Molecular Sequence Data , Peptide Library , Peptides/geneticsABSTRACT
The envelope glycoprotein, gp120, on the surface of HIV interacts with the human CD4 molecule and thus helps the virus in gaining entry into the T-helper cells. To display the gp120 binding domains of human CD4 on the surface of the bacteriophage M13, two types of vectors have been constructed. In these, the first 176 amino acids of the human CD4 have been fused with the minor coat protein, gIIIp, of M13 bacteriophage for surface display. The Western blot analysis revealed that using the phage based vector, M13CD41923, all the copies of gIIIP (3-5 per virion) were present as fusion protein indicating multivalent display. In the phagemid based vector, phage particles were produced only upon infection of the cells carrying pVCCD43426, with the helper phage, M13KO7. Thus these phage particles carried both, the fusion protein as well as the unfused gIIIp, as shown by Western blot analysis. The presence of large amount of unfused gIIIp ensured that the phage particles did not display more than one fusion protein per phage particle, thus leading to monovalent display. Phage particles produced by both vectors could be captured on immobilized gp120, thereby showing that the displayed CD4 domains were functional.