title: Immunogenicity of HIV type 1 gp120 CD4 binding site phage mimotopes.
abstract: The conserved domain of the CD4 binding site (CD4bs) on the human immunodeficiency virus type 1 (HIV- 1) envelope represents a potential target for vaccine development. Here we describe selection of peptide mimotopes by panning a phage peptide library on the HIV-1 CD4bs-specific, broadly neutralizing anti-HIV-1 monoclonal antibody, IgG(1) b12. We identified an initial consensus sequence for IgG1 b12 binding (M/VThetaSD, where Theta represents an aromatic amino acid). A molecular evolution approach, using second- and third-generation libraries, led us to identify a refined consensus sequence (GLLVWSDEL). The resulting IgG1 b12 phage mimotopes compete with gp160 for the IgG1 b12 antigen-binding site, but the phage coat protein (pIII) may play an important structural role, since both free peptides and KLH-conjugated peptides have no detectable binding activity. Mice immunized with IgG1 b12 phage mimotopes elicited a weak but persistent humoral response directed against the HIV-1 envelope. An antibody fragment was isolated from the antibody repertoires of these animals. It is noteworthy that while it has a relatively low affinity for HIV-1 gp160, the antibody targets an epitope that overlaps with that of IgG1 b12. Our data therefore suggest that engineered IgG1 b12 mimotopes share immunogenic features with the CD4bs. However, these peptidic structures will require further improvement in order to generate broad specificity neutralizing antibodies like IgG1 b12.
authors.affiliation: Immunologie A, CERVI, INSERM U543 and Université Pierre et Marie Curie, Hôpital Pitié-Salpêtrière, 75013 Paris, France.
authors.forename: Karim
authors.initials: K
authors.lastname: Dorgham
authors.forename: Ismaïl
authors.initials: I
authors.lastname: Dogan
authors.forename: Natacha
authors.initials: N
authors.lastname: Bitton
authors.forename: Christophe
authors.initials: C
authors.lastname: Parizot
authors.forename: Valerie
authors.initials: V
authors.lastname: Cardona
authors.forename: Patrice
authors.initials: P
authors.lastname: Debré
authors.forename: Oliver
authors.initials: O
authors.lastname: Hartley
authors.forename: Guy
authors.initials: G
authors.lastname: Gorochov
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001435:Bacteriophages / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D015704:CD4 Antigens / Q000378:metabolism*; D005260:Female; D015483:HIV Antibodies / Q000097:blood; D015699:HIV Envelope Protein gp120 / Q000737:chemistry* / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007114:Immunization; D007074:Immunoglobulin G / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D019151:Peptide Library; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D007074:Immunoglobulin G; D019151:Peptide Library; D010455:Peptides