Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, USA.
Department of Surgery, Duke University School of Medicine, Durham, North Carolina, USA.
J Virol. 2014 Aug;88(16):9406-17. doi: 10.1128/JVI.01031-14. Epub 2014 Jun 11.
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.
糖鞘脂半乳糖脑苷脂已被推测为 HIV-1 包膜（Env）与黏膜上皮细胞相互作用的受体。通过破坏 HIV-1 Env 与替代受体的相互作用，可能是阻止 HIV-1 通过黏膜屏障进入的一种策略。为了研究抗体对 HIV-1 Env-Galcer 相互作用的调节作用，我们使用含有 Galcer 的脂质体来评估天然和疫苗诱导的单克隆抗体是否可以阻断 HIV-1 Env 与 Galcer 的结合。HIV-1 Env gp140 蛋白与 Galcer 脂质体结合的 Kd（解离常数）在纳摩尔范围内。几种针对 gp120 第一恒定（C1）区的 HIV-1 ALVAC/AIDSVAX 疫苗衍生的单克隆抗体（Mab）特异性阻断了传播/起始 HIV-1 Env gp140 与 Galcer 的结合。在显示 Galcer 阻断的 C1 特异性 Mab 中，抗体依赖性细胞毒性介导的 CH38 IgG 及其天然 IgA 同种型是最有效的阻断抗体。阻断 Env 与 Galcer 结合的 C1 特异性 IgG 单克隆抗体诱导 MAb 17B 结合的 gp120 CD4 诱导表位（CD4i）上调，表明 gp120 的构象变化可能是 Galcer 阻断所必需的。然而，单抗 17B 本身不能阻断 Env-Galcer 结合，这表明 C1 抗体诱导的 gp120 构象变化导致与 CD4i 17B 单抗结合位点远离的 Galcer 结合位点发生改变。
半乳糖脑苷脂是一种糖鞘脂，已被推测为 HIV-1 包膜糖蛋白（Env）与黏膜上皮细胞相互作用的受体。在这里，我们通过使用含有合成 Galcer 和重组 HIV-1 Env 蛋白的人工膜模拟这种相互作用，来鉴定可以阻断 HIV-1 Env-Galcer 相互作用的抗体。我们的研究表明，一类疫苗诱导的人类抗体通过扰乱 HIV-1 Env 构象，强力阻断 HIV-1 Env-Galcer 结合。
