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  • Vaccine-induced HIV-1 envelope gp120 constant region 1-specific antibodies expose a CD4-inducible epitope and block the interaction of HIV-1 gp140 with galactosylceramide.

Vaccine-induced HIV-1 envelope gp120 constant region 1-specific antibodies expose a CD4-inducible epitope and block the interaction of HIV-1 gp140 with galactosylceramide.

Journal of virology (2014-06-13)
S Moses Dennison, Kara M Anasti, Frederick H Jaeger, Shelley M Stewart, Justin Pollara, Pinghuang Liu, Erika L Kunz, Ruijun Zhang, Nathan Vandergrift, Sallie Permar, Guido Ferrari, Georgia D Tomaras, Mattia Bonsignori, Nelson L Michael, Jerome H Kim, Jaranit Kaewkungwal, Sorachai Nitayaphan, Punnee Pitisuttithum, Supachai Rerks-Ngarm, Hua-Xin Liao, Barton F Haynes, S Munir Alam
ABSTRACT

Mucosal epithelial cell surface galactosylceramide (Galcer) has been postulated to be a receptor for HIV-1 envelope (Env) interactions with mucosal epithelial cells. Disruption of the HIV-1 Env interaction with such alternate receptors could be one strategy to prevent HIV-1 entry through the mucosal barrier. To study antibody modulation of HIV-1 Env-Galcer interactions, we used Galcer-containing liposomes to assess whether natural- and vaccine-induced monoclonal antibodies can block HIV-1 Env binding to Galcer. HIV-1 Env gp140 proteins bound to Galcer liposomes with Kds (dissociation constants) in the nanomolar range. Several HIV-1 ALVAC/AIDSVAX vaccinee-derived monoclonal antibodies (MAbs) specific for the gp120 first constant (C1) region blocked Galcer binding of a transmitted/founder HIV-1 Env gp140. Among the C1-specific MAbs that showed Galcer blocking, the antibody-dependent cellular cytotoxicity-mediating CH38 IgG and its natural IgA isotype were the most potent blocking antibodies. C1-specific IgG monoclonal antibodies that blocked Env binding to Galcer induced upregulation of the gp120 CD4-inducible (CD4i) epitope bound by MAb 17B, demonstrating that a conformational change in gp120 may be required for Galcer blocking. However, the MAb 17B itself did not block Env-Galcer binding, suggesting that the C1 antibody-induced gp120 conformational changes resulted in alteration in a Galcer binding site distant from the CD4i 17B MAb binding site. Galactosyl ceramide, a glycosphingolipid, has been postulated to be a receptor for the HIV-1 envelope glycoprotein (Env) interaction with mucosal epithelial cells. Here, we have mimicked this interaction by using an artificial membrane containing synthetic Galcer and recombinant HIV-1 Env proteins to identify antibodies that would block the HIV-1 Env-Galcer interaction. Our study revealed that a class of vaccine-induced human antibodies potently blocks HIV-1 Env-Galcer binding by perturbing the HIV-1 Env conformation.

MATERIALS
Product Number
Brand
Product Description

Supelco
Residual Solvent - Chloroform, Pharmaceutical Secondary Standard; Certified Reference Material
Avanti
C8 Galactosyl(β) Ceramide (d18:1/8:0), Avanti Research - A Croda Brand 860538P, powder
Avanti
C18:1 Galactosyl(β) Ceramide (d18:1/18:1(9Z)), Avanti Research - A Croda Brand 860596P, powder
Supelco
Chloroform, analytical standard
Sigma-Aldrich
Chloroform, anhydrous, ≥99%, contains 0.5-1.0% ethanol as stabilizer
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Chloroform, anhydrous, contains amylenes as stabilizer, ≥99%
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Chloroform, ≥99%, PCR Reagent, contains amylenes as stabilizer
Supelco
Chloroform, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Chloroform, suitable for HPLC, ≥99.8%, contains 0.5-1.0% ethanol as stabilizer
Sigma-Aldrich
Chloroform, ACS spectrophotometric grade, ≥99.8%, contains 0.5-1.0% ethanol as stabilizer
Sigma-Aldrich
Chloroform, contains ethanol as stabilizer, meets analytical specification of BP, 99-99.4% (GC)
Avanti
C16 Galactosyl(β) Ceramide (d18:1/16:0), Avanti Research - A Croda Brand 860521P, powder
Sigma-Aldrich
Chloroform, ReagentPlus®, ≥99.8%, contains 0.5-1.0% ethanol as stabilizer
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Chloroform, contains 100-200 ppm amylenes as stabilizer, ≥99.5%
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Chloroform, biotech. grade, ≥99.8%, contains 0.5-1.0% ethanol as stabilizer
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Chloroform, puriss. p.a., reag. ISO, reag. Ph. Eur., 99.0-99.4% (GC)
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Chloroform, suitable for HPLC, ≥99.8%, amylene stabilized
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Chloroform, HPLC Plus, for HPLC, GC, and residue analysis, ≥99.9%, contains 0.5-1.0% ethanol as stabilizer
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Chloroform, HPLC Plus, for HPLC, GC, and residue analysis, ≥99.9%, contains amylenes as stabilizer