Studies with monoclonal antibodies to the V3 region of HIV-1 gp120 reveal limitations to the utility of solid-phase peptide binding assays.
Using human monoclonal antibodies (HuMAbs) r(1)-447 (L-736,523) and 19b to the V3 region of HIV-1 gp120, we have explored epitope presentation on V3-peptides and on the corresponding gp120 proteins. HuMAb r(1)-447 binds strongly to the MN and SF-2 peptides and gp120 proteins. In contrast, while this HuMAb binds equally avidly to both the HxB2 and the BRU/BH10 peptides, it binds but weakly to the HxB2 V3 loop on gp120 and fails to bind at all to BH10 gp120. Thus, the solid-phase peptide binding assay can falsely predict reactivity of an MAb with a gp120 protein. Conversely, HuMAb 19b fails to bind to a peptide from the V3 loop of HIV-1 AD-6 in solid-phase assays, but binds to the same peptide in solution and also to AD-6 gp120. Thus, the solid-phase peptide binding assay can fail to predict reactivity of an MAb with a gp120 protein. Furthermore, serum antibodies from individual AD-6 do not react well with the AD-6 V3-peptide in a solid-phase assay, but react strongly with the corresponding MN V3-peptide. On the basis of peptide binding assays, we had assumed that the AD-6 virus was "MN-like" with a prototypic North American/European subtype B GPGR motif at the crown of the V3 loop. However, direct sequencing demonstrates that the AD-6 V3 loop contains a variant GPGK motif. This highlights a limitation of V3-peptide-based assays for serotyping viruses.
Moore
J P
JP
Aaron Diamond AIDS Research Center, New York University School of Medicine, NY 10016.
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Conley
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Wyatt
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Robinson
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Gorny
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Zolla-Pazner
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D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001667:Binding, Competitive; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000276:immunology; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000276:immunology*; D015497:HIV-1 / Q000145:classification / Q000276:immunology*; D006801:Humans; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology*; D011110:Polymorphism, Genetic; D011994:Recombinant Proteins / Q000276:immunology; D012680:Sensitivity and Specificity; D012703:Serotyping
D000911:Antibodies, Monoclonal; D000939:Epitopes; D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments; D011994:Recombinant Proteins