The elicitation of broadly neutralizing antibodies (bNAbs) against the HIV-1 envelope glycoprotein (Env) trimer remains a major vaccine challenge. Most cross-conserved protein determinants are occluded by self-N-glycan shielding, limiting B cell recognition of the underlying polypeptide surface. The exceptions to the contiguous glycan shield include the conserved receptor CD4 binding site (CD4bs) and glycoprotein (gp)41 elements proximal to the furin cleavage site. Accordingly, we performed heterologous trimer-liposome prime:boosting in rabbits to drive B cells specific for cross-conserved sites. To preferentially expose the CD4bs to B cells, we eliminated proximal N-glycans while maintaining the native-like state of the cleavage-independent NFL trimers, followed by gradual N-glycan restoration coupled with heterologous boosting. This approach successfully elicited CD4bs-directed, cross-neutralizing Abs, including one targeting a unique glycan-protein epitope and a bNAb (87% breadth) directed to the gp120:gp41 interface, both resolved by high-resolution cryoelectron microscopy. This study provides proof-of-principle immunogenicity toward eliciting bNAbs by vaccination.

中文翻译：

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用聚糖修饰的 HIV NFL 包膜三聚体脂质体接种疫苗可引发针对多个易损部位的广泛中和抗体。

诱导针对 HIV-1 包膜糖蛋白 (Env) 三聚体的广泛中和抗体 (bNAb) 仍然是一项主要的疫苗挑战。大多数交叉保守的蛋白质决定簇被自身 N-聚糖屏蔽所封闭，从而限制了 B 细胞对底层多肽表面的识别。连续聚糖屏蔽的例外包括靠近弗林蛋白酶切割位点的保守受体 CD4 结合位点 (CD4bs) 和糖蛋白 (gp)41 元件。因此，我们在兔子中进行了异源三聚体-脂质体启动：增强以驱动对交叉保守位点特异的 B 细胞。为了优先将 CD4bs 暴露给 B 细胞，我们消除了近端 N-聚糖，同时保持了不依赖切割的 NFL 三聚体的天然样状态，然后逐渐恢复 N-聚糖并结合异源增强。这种方法成功地引发了 CD4bs 导向的交叉中和 Abs，包括一个靶向独特的聚糖蛋白表位和一个指向 gp120:gp41 界面的 bNAb（87% 宽度），两者都通过高分辨率冷冻电子显微镜解决。这项研究为通过疫苗接种引发 bNAbs 提供了原理证明的免疫原性。