Evaluation of the epitope specificities, locations (systemic or mucosal), and effector functions of antibodies elicited by novel HIV-1 immunogens engineered to improve exposure of specific epitopes is critical for HIV-1 vaccine development. Utilizing an array of humoral assays, we evaluated the magnitudes, epitope specificities, avidities, and functions of systemic and mucosal immune responses elicited by a vaccine regimen containing Env cross-linked to a CD4-mimetic miniprotein (gp140-M64U1) in rhesus macaques. Cross-linking of gp140 Env to M64U1 resulted in earlier increases of both the magnitude and avidity of the IgG binding response than those with Env protein alone. Notably, IgG binding responses at an early time point correlated with antibody-dependent cellular cytotoxicity (ADCC) function at the peak immunity time point, which was higher for the cross-linked Env group than for the Env group. In addition, the cross-linked Env group developed higher IgG responses against a linear epitope in the gp120 C1 region of the HIV-1 envelope glycoprotein. These data demonstrate that structural modification of the HIV-1 envelope immunogen by cross-linking of gp140 with the CD4-mimetic M64U1 elicited an earlier increase of binding antibody responses and altered the specificity of the IgG responses, correlating with the rise of subsequent antibody-mediated antiviral functions.

IMPORTANCE The development of an efficacious HIV-1 vaccine remains a global priority to prevent new cases of HIV-1 infection. Of the six HIV-1 efficacy trials to date, only one has demonstrated partial efficacy, and immune correlate analysis of that trial revealed a role for binding antibodies and antibody Fc-mediated effector functions. New HIV-1 envelope immunogens are being engineered to selectively expose the most vulnerable and conserved sites on the HIV-1 envelope, with the goal of eliciting antiviral antibodies. Evaluation of the humoral responses elicited by these novel immunogen designs in nonhuman primates is critical for understanding how to improve upon immunogen design to inform further testing in human clinical trials. Our results demonstrate that structural modifications of Env that aim to mimic the CD4-bound conformation can result in earlier antibody elicitation, altered epitope specificity, and increased antiviral function postimmunization.

评价新的HIV-1免疫原引发的抗体的表位特异性，位置（全身或粘膜）和效应子功能的评估对于HIV-1疫苗的开发至关重要。我们利用一系列体液检测方法，评估了猕猴猕猴中由含Env的疫苗接种方案引起的系统性和粘膜免疫应答的大小，抗原决定簇特异性，亲和力和功能，该Env疫苗与CD4模仿的小蛋白（gp140-M64U1）交联。gp140 Env与M64U1的交联比单独使用Env蛋白的IgG结合反应的幅度和亲和力都更早增加。值得注意的是，早期的IgG结合反应与峰值免疫时间点的抗体依赖性细胞毒性（ADCC）功能相关，交联的Env组高于Env组。另外，交联的Env基团对HIV-1包膜糖蛋白的gp120C1区域中的线性表位产生了更高的IgG应答。这些数据表明，通过gp140与CD4-拟态M64U1的交联对HIV-1包膜免疫原进行结构修饰会引起结合抗体应答的较早增加，并改变IgG应答的特异性，这与后续抗体的产生有关。介导的抗病毒功能。

重要性有效的HIV-1疫苗的开发仍然是防止HIV-1感染新病例的全球优先事项。迄今为止，在六项HIV-1功效试验中，只有一项已显示出部分功效，对该试验的免疫相关分析显示了结合抗体和抗体Fc介导的效应子功能的作用。正在设计新的HIV-1包膜免疫原，以选择性地暴露HIV-1包膜上最脆弱和保守的位点，目的是引发抗病毒抗体。这些新颖的免疫原设计在非人类灵长类动物中引发的体液反应的评估对于理解如何改善免疫原设计以为人类临床试验中的进一步测试提供信息至关重要。