Salimi Hamid, Johnson Jacklyn, Flores Manuel G, Zhang Michael S, O'Malley Yunxia, Houtman Jon C, Schlievert Patrick M, Haim Hillel
Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242.
Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242.
J Biol Chem. 2020 Jan 10;295(2):348-362. doi: 10.1074/jbc.RA119.009481. Epub 2019 Nov 22.
The envelope glycoproteins (Envs) of HIV-1 are embedded in the cholesterol-rich lipid membrane of the virus. Chemical depletion of cholesterol from HIV-1 particles inactivates their infectivity. We observed that diverse HIV-1 strains exhibit a range of sensitivities to such treatment. Differences in sensitivity to cholesterol depletion could not be explained by variation in Env components known to interact with cholesterol, including the cholesterol-recognition motif and cytoplasmic tail of gp41. Using antibody-binding assays, measurements of virus infectivity, and analyses of lipid membrane order, we found that depletion of cholesterol from HIV-1 particles decreases the conformational stability of Env. It enhances exposure of partially cryptic epitopes on the trimer and increases sensitivity to structure-perturbing treatments such as antibodies and cold denaturation. Substitutions in the cholesterol-interacting motif of gp41 induced similar effects as depletion of cholesterol. Surface-acting agents, which are incorporated into the virus lipid membrane, caused similar effects as disruption of the Env-cholesterol interaction. Furthermore, substitutions in gp120 that increased structural stability of Env ( induced a "closed" conformation of the trimer) increased virus resistance to cholesterol depletion and to the surface-acting agents. Collectively, these results indicate a critical contribution of the viral membrane to the stability of the Env trimer and to neutralization resistance against antibodies. Our findings suggest that the potency of poorly neutralizing antibodies, which are commonly elicited in vaccinated individuals, may be markedly enhanced by altering the lipid composition of the viral membrane.
HIV-1的包膜糖蛋白（Envs）嵌入病毒富含胆固醇的脂质膜中。从HIV-1颗粒中化学去除胆固醇会使其失去感染性。我们观察到不同的HIV-1毒株对这种处理表现出不同程度的敏感性。对胆固醇去除的敏感性差异无法用已知与胆固醇相互作用的Env组分的变化来解释，包括gp41的胆固醇识别基序和细胞质尾巴。通过抗体结合试验、病毒感染性测量以及脂质膜有序性分析，我们发现从HIV-1颗粒中去除胆固醇会降低Env的构象稳定性。它增强了三聚体上部分隐蔽表位的暴露，并增加了对诸如抗体和冷变性等结构扰动处理的敏感性。gp41中胆固醇相互作用基序的替代诱导了与胆固醇去除类似的效果。掺入病毒脂质膜的表面活性剂产生了与Env-胆固醇相互作用破坏类似的效果。此外，gp120中增加Env结构稳定性（诱导三聚体的“封闭”构象）的替代增加了病毒对胆固醇去除和表面活性剂的抗性。总体而言，这些结果表明病毒膜对Env三聚体的稳定性以及对抗体中和抗性具有关键作用。我们的研究结果表明，通过改变病毒膜的脂质组成，疫苗接种个体中通常诱导产生的低效中和抗体的效力可能会显著增强。
