Departments of Pediatrics and Microbiology & Immunology, Stanford University School of Medicine, Stanford, California, United States of America.
Department of Infectious Diseases, The Scripps Research Institute, Jupiter, Florida, United States of America.
PLoS One. 2018 Oct 25;13(10):e0206365. doi: 10.1371/journal.pone.0206365. eCollection 2018.
Human Immunodeficiency Virus-1 (HIV-1) entry is dependent on the envelope glycoprotein (Env) that is present on the virion and facilitates fusion between the envelope and the cellular membrane. The protein consists of two subunits, gp120 and gp41, with the former required for binding the CD4 receptor and either the CXCR4 or CCR5 coreceptor, and the latter for mediating fusion. The requirement of fusion for infection has made Env an attractive target for HIV therapy development and led to the FDA approval of enfuvirtide, a fusion inhibitor. Continued development of entry inhibitors is warranted because enfuvirtide resistant HIV-1 strains have emerged. In this study, a novel HIV-1 fusion assay was validated using neutralizing antibodies and then used to investigate the mechanism of action of eCD4-Igmim2, an HIV-1 inhibitor proposed to cooperatively bind the CD4 binding site and the sulfotyrosine-binding pocket of gp120. Greater reduction in fusion levels was observed with eCD4-Igmim2 in the fusion assay than all of the gp120 antibodies evaluated. Lab adapted isolates, HIV-1HXB2 and HIV-1YU2, were sensitive to eCD4-Igmim2 in the fusion assay, while primary isolates, HIV-1BG505 and HIV-1ZM651 were resistant. These results correlated with greater IC50 values for primary isolates compared to the lab adapted isolates observed in a virus neutralization assay. Analysis of gp120 models identified differences in the V1 and V2 domains that are associated with eCD4-Igmim2 sensitivity. This study highlights the use of a fusion assay to identify key areas for improving the potency of eCD4-Igmim2.
人类免疫缺陷病毒 1 型（HIV-1）的进入依赖于存在于病毒粒子上的包膜糖蛋白（Env），它促进包膜与细胞膜之间的融合。该蛋白由两个亚基 gp120 和 gp41 组成，前者需要与 CD4 受体结合，或者与 CXCR4 或 CCR5 核心受体结合，后者介导融合。感染需要融合，这使得 Env 成为 HIV 治疗开发的有吸引力的靶标，并导致 enfuvirtide 的 FDA 批准，一种融合抑制剂。需要继续开发进入抑制剂，因为已经出现了 enfuvirtide 耐药的 HIV-1 株。在这项研究中，使用中和抗体验证了一种新型 HIV-1 融合测定法，然后用于研究 HIV-1 抑制剂 eCD4-Igmim2 的作用机制，该抑制剂拟合作地结合 CD4 结合位点和 gp120 的磺酸酪氨酸结合口袋。在融合测定中，与评估的所有 gp120 抗体相比，eCD4-Igmim2 观察到融合水平的更大降低。在融合测定中，实验室适应的分离株 HIV-1HXB2 和 HIV-1YU2 对 eCD4-Igmim2 敏感，而原发性分离株 HIV-1BG505 和 HIV-1ZM651 耐药。这些结果与在病毒中和测定中观察到的原发性分离株比实验室适应的分离株的 IC50 值更高的结果相关。对 gp120 模型的分析确定了与 eCD4-Igmim2 敏感性相关的 V1 和 V2 结构域的差异。这项研究强调了使用融合测定法来确定提高 eCD4-Igmim2 效力的关键区域。
