A Conserved Region at the COOH Terminus of Human Immunodeficiency Virus Gp120 Envelope Protein Contains an Immunodominant Epitope

• Published in: Proceedings of the National Academy of Sciences - PNAS 1987-04, Vol.84 (8), p.2479-2483
• Main Authors: Palker, Thomas J., Matthews, Thomas J., Clark, Michael E., Cianciolo, George J., Randall, Richard R., Langlois, Alphonse J., White, Gilbert C., Safai, Bijan, Snyderman, Ralph, Bolognesi, Dani P., Haynes, Barton F.
• Format: Article
• Language: English
• Subjects: Acquired Immunodeficiency Syndrome - immunology; AIDS; AIDS/HIV; Amino Acid Sequence; Amino acids; Antibodies; Antibodies, Viral - analysis; Antigens; Biological and medical sciences; DNA Replication; Epitopes; Epitopes - analysis; Fundamental and applied biological sciences. Psychology; Giant cells; HIV; HIV - analysis; HIV - genetics; HIV - immunology; HIV Antibodies; human immunodeficiency virus; Humans; Immunodominant epitopes; Microbiology; Morphology, structure, chemical composition, physicochemical properties; Neutralization Tests; Peptides - chemical synthesis; Radioimmunoassay; Reactivity; Viral Envelope Proteins - analysis; Viral Envelope Proteins - immunology; Virology; Virus Replication; Viruses
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.84.8.2479

A highly immunogenic epitope from a conserved COOH-terminal region of the human immunodeficiency virus (HIV) gp120 envelope protein has been identified with antisera from HIV-seropositive subjects and a synthetic peptide (SP-22) containing 15 amino acids from this region (Ala-Pro-Thr-Lys-Ala-Lys-Arg-Arg-Val-Val-Gln-Arg-Glu-Lys-Arg). Peptide SP-22 absorbed up to 100% of anti-gp120 antibody reactivity from select HIV+patient sera in immunoblot assays and up to 79% of serum anti-gp120 antibody reactivity in competition RIA. In RIA, 45% of HIV-seropositive subjects had antibodies that bound to peptide SP-22. Human anti-SP-22 antibodies that bound to and were eluted from an SP-22 affinity column reacted with gp120 in RIA and immunoblot assays but did not neutralize HIV or inhibit HIV-induced syncytium formation in vitro, even though these antibodies comprised 70% of all anti-gp120 antibodies in the test serum. In contrast, the remaining 30% of SP-22 nonreactive anti-gp120 antibodies did not react with gp120 in immunoblot assays but did react in RIA and neutralized HIV in vitro. Thus, ≈ 50% of HIV-seropositive patients make high titers of nonneutralizing antibodies to an immunodominant antigen on gp120 defined by SP-22. Moreover, the COOH terminus of gp120 contains the major antigen or antigens identified by human anti-gp120 antibodies in immunoblot assays.