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

项目摘要 有效的HIV-1疫苗将是一种激发多种抗病毒免疫应答的疫苗，包括广泛的 中和抗体（bnAb）。我们专注于抗CD 4结合位点（CD 4-BS）bnAb的诱导， 包括VRC 01类bnAb，通过指导免疫方法，使用专门设计的Env衍生的 蛋白免疫原。我们先前报道了一种进化枝C Env衍生的免疫原的设计， 体内表达VRC 01类抗体的bnAb前体的幼稚B细胞。我们还报道了 设计衍生自进化枝B Env的第二免疫原，当作为第一次加强施用时， 新出现的VRC 01 B细胞应答的成熟。我们目前的建议是基于我们最近的 观察到，用稳定的可溶性三聚体Env（SOSIP）的混合物进行的第二次加强免疫驱动了 这些VRC 01 B细胞的成熟更接近于它们的完全成熟，使得所引发的抗体显示 与常规抗病毒药物相比，对某些异源2级病毒的交叉中和潜力大大提高， 第一次加强后产生的抗体。然而，这种成熟过程仍然是不完全的， 由第二次加强引起的不显示与完全成熟的人类VRC 01相同的中和呼吸- 从HIV+受试者中分离的类抗体。我们期望，并建议通过实验验证， 用这种稳定的Env三聚体的混合物进行额外的免疫， （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VRC 01 B细胞的成熟和抗体应答 被呈递给免疫系统。具体来说，我们将比较体细胞突变的类型和速率- 当免疫原作为抗体施用时， 佐剂化的重组蛋白或通过自扩增平台（saRNA）在体内表达。另一 我们建议的一个重要方面是，我们不会将我们的工作局限于控制良好的基因敲入小鼠， 表达人VH/VL基因的转基因小鼠。因为这些小鼠的B细胞库 反映了人类的情况，我们希望我们优化的免疫方案不仅能激活更广泛的免疫系统， 一系列的VRC 01类抗体比它在敲入小鼠模型，但额外的类别的抗- 还将引发CD 4-BS抗体应答。

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.