Guiding the maturation of anti-CD4-BS bnAbs through sequential heterologous Env immunization

项目总结 一种有效的HIV-1疫苗将会引起不同的抗病毒免疫反应，包括 中和抗体(BNAbs)。我们专注于抗CD4结合位点(CD4BS)bNAbs的诱导， 包括VRC01类bNAbs，通过专门设计的环境衍生的引导免疫方法 蛋白质免疫原。我们之前报道了一种C型包膜衍生免疫原的设计，它可以激活 体内表达VRC01类抗体bNab前体的幼稚B细胞。我们还报道了 从分支B环境衍生的第二种免疫原的设计，当作为第一次加强注射时，增加 出现的VRC01B细胞反应的成熟。我们目前的建议是基于我们最新的 用稳定的可溶性三聚体EVS(SOSIPs)鸡尾酒进行第二次加强免疫的观察 这些VRC01B细胞的成熟接近于它们的完全成熟，因此所激发的抗体显示 大大提高了对某些异源2级病毒的交叉中和潜力 第一次免疫后产生抗体。然而，这种成熟过程仍然不完整，而且抗体 由第二次助推引发的病毒不会表现出与完全成熟的人VRC01一样的中和气息- 从HIV受试者身上分离出的类抗体。我们预计，并建议通过实验验证，他们的 这种稳定的环境三聚体的鸡尾酒将通过额外的免疫来完成成熟 (SOSIP)或这些SOSIP的特定子集。我们建议的一个重要方面是我们将比较 免疫原如何影响VRC01B细胞的成熟和抗体反应 呈现给免疫系统。具体地说，我们将比较体细胞突变的类型和比率- 当免疫原作为免疫原注射时，相应抗体的积累和质量 佐剂重组蛋白或通过自扩增平台(SARNA)在体内表达。另一个 我们建议的重要方面是，我们不会将我们的工作局限于控制良好的敲入老鼠，而是 表达人类VH/VL基因的转基因小鼠也是如此。因为这些小鼠的B细胞库更好 我们预计，我们优化的免疫方案不仅将激活更广泛的 VRC01类抗体的范围比它在敲入小鼠模型中的作用更大，但这种额外的抗类抗体 也会引起CD4-BS抗体反应。

PROJECT SUMMARY An effective HIV-1 vaccine will be one that elicits diverse anti-viral immune responses, including broadly neutralizing antibodies (bnAbs). We are focused on the elicitation of anti-CD4-binding site (CD4-BS) bnAbs, including VRC01-class bnAbs, through a guided immunization approach with specifically designed Env-derived protein immunogens. We previously reported on the design of a clade C Env-derived immunogen that activates naïve B cells expressing the bnAb precursors of VRC01-class antibodies in vivo. We also reported on the design of a second immunogen derived from a clade B Env that, when administered as a 1st boost, increases the maturation of the emerging VRC01 B cell responses. Our current proposal is based on our very recent observations that a 2nd booster immunization with a cocktail of stabilized soluble trimeric Envs (SOSIPs) drives the maturation of these VRC01 B cells closer to their full maturation, so that the elicited antibodies display vastly improved cross-neutralizing potentials against certain heterologous, tier 2 viruses as compared to the antibodies elicited after the 1st boost. However, this maturation process is still incomplete, and the antibodies elicited by the 2nd boost do not display the same breath of neutralization as the fully matured human VRC01- class antibodies isolated from HIV+ subjects. We expect, and propose to validate experimentally, that their maturation will be completed with additional immunizations with this cocktail of stabilized Env trimers (SOSIPs), or a specific subset of these SOSIPs. An important aspect of our proposal is that we will compare how the maturation of the VRC01 B cell and antibody responses may be affected by the way the immunogens are presented to the immune system. Specifically, we will compare the type and rates of somatic mutation- accumulation and the quality of the corresponding antibodies, when the immunogens are administered as adjuvanted recombinant proteins or expressed in vivo by a self-amplifying platform (saRNA). Another important aspect of our proposal is that we will not limit our work to well-controlled knock-in mice, but transgenic mice that express human VH/VL genes, as well. Because the B cell repertoire of these mice better reflect that of humans, we expect that our optimized immunization schema will not only activate a broader range of VRC01-class antibodies than it does in the knock-in mouse models, but that additional classes of anti- CD4-BS antibody responses will also be elicited.