Recognition properties of V3-specific antibodies to V3 loop peptides derived from HIV-1 gp120 presented in multiple conformations.
To identify structural constraints and amino acid sequences important for antibody recognition of the third variable domain (V3) of HIV-1 gp120, we have studied the solution conformation of three 35-mer circular V3 loop peptides derived from HIV-1 strains which differ in syncytium- (SI) and non-syncytium-inducing (NSI) capacity. In addition to 2D NMR and CD analyses, fluid- and solid-phase immunoassays were performed using V3-specific antibodies to V3 peptides and gp120 derived from different strains of HIV-1. NMR and CD spectroscopy indicated that circular and linear V3 loops exist in water as a dynamic ensemble of multiple conformations. Amino acid substitutions and biochemical modifications of the V3 loop were found to affect antibody binding depending on the presentation of the antigens. From NMR observations and immunological experiments, we provide evidence for a V3 loop specific monoclonal antibody interaction which is directed predominantly against linear epitopes rather than against discontinuous epitopes. The absence of a single defined solution conformation of 35-mer circular V3 peptides should be taken into account when using V3-related peptides to investigate structural elements in the V3 domain of the gp120 envelope protein of HIV-1 involved in biological processes of the virus.
Huisman
J G
JG
CLB, Sanquin Blood Supply Foundation, Laboratory for Clinical and Experimental Immunology, Department of Pathophysiology of Plasma Proteins, Amsterdam, The Netherlands.
Carotenuto
A
A
Labrijn
A F
AF
Papavoine
C H
CH
Laman
J D
JD
Schellekens
M M
MM
Koppelman
M H
MH
Hilbers
C W
CW
D000595:Amino Acid Sequence; D000918:Antibody Specificity; D017951:Antigen Presentation; D000937:Antigen-Antibody Reactions; D002942:Circular Dichroism; D004797:Enzyme-Linked Immunosorbent Assay; D015726:Giant Cells / Q000821:virology; D015483:HIV Antibodies / Q000378:metabolism*; D015488:HIV Antigens / Q000276:immunology / Q000378:metabolism; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*; D015497:HIV-1 / Q000737:chemistry / Q000276:immunology* / Q000502:physiology; D006868:Hydrolysis; D008745:Methylation; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism*; D010641:Phenotype; D011487:Protein Conformation; D011489:Protein Denaturation; D011863:Radioimmunoassay; D013816:Thermodynamics; D013917:Thrombin / Q000378:metabolism; D014867:Water
D015483:HIV Antibodies; D015488:HIV Antigens; D015699:HIV Envelope Protein gp120; D010446:Peptide Fragments; D014867:Water; D013917:Thrombin