Identification and characterization of a peptide that specifically binds the human, broadly neutralizing anti-human immunodeficiency virus type 1 antibody b12.
Human monoclonal antibody (MAb) b12 recognizes a conformational epitope that overlaps the CD-4-binding site of the human immunodeficiency virus type 1 (HIV-1) envelope. MAb b12 neutralizes a broad range of HIV-1 primary isolates and protects against primary virus challenge in animal models. We report here the discovery and characterization of B2.1, a peptide that binds specifically to MAb b12. B2.1 was selected from a phage-displayed peptide library by using immunoglobulin G1 b12 as the selecting agent. The peptide is a homodimer whose activity depends on an intact disulfide bridge joining its polypeptide chains. Competition studies with gp120 indicate that B2.1 occupies the b12 antigen-binding site. The affinity of b12 for B2.1 depends on the form in which the peptide is presented; b12 binds best to the homodimer as a recombinant polypeptide fused to the phage coat. Originally, b12 was isolated from a phage-displayed Fab library constructed from the bone marrow of an HIV-1-infected donor. The B2.1 peptide is highly specific for b12 since it selected only phage bearing b12 Fab from this large and diverse antibody library.
Zwick
M B
MB
Department of Molecular Biology and Biochemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.
Bonnycastle
L L
LL
Menendez
A
A
Irving
M B
MB
Barbas
C F
CF
Parren
P W
PW
Burton
D R
DR
Scott
J K
JK
D000911:Antibodies, Monoclonal / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D015658:HIV Infections / Q000517:prevention & control; D015497:HIV-1 / Q000737:chemistry*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D009500:Neutralization Tests; D010455:Peptides / Q000737:chemistry / Q000276:immunology*; D011485:Protein Binding; D012680:Sensitivity and Specificity; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D007074:Immunoglobulin G; D010455:Peptides; D014759:Viral Envelope Proteins