Expediting elicitation of HIV-1 bnAbs with membrane Env vaccines

项目总结/摘要 HIV/AIDS疫苗开发的主要目标是引发针对HIV-1的广泛中和抗体（bnAb）。 锚定在膜中的包膜糖蛋白刺突（m-Env）。到目前为止，实验性疫苗主要引起了 窄的、弱的或非中和抗体，通常使用可溶性Env（s-Env）分子。在这里，我们将使用膜 Env脂质体（MEL）疫苗，其通过脂质体结合良好有序且稳定的m-Env三聚体到脂质体中。 跨膜结构域因此，MEL以多价方式呈现Env的相关构象，并含有重要的 膜近端外部区域（MPER）的表位，其在s-Env疫苗中缺失。创建MEL 通过最近通过创建高Env生产细胞对m-Env生产的改进而变得可行。同时， B细胞无反应性在HIV-1 bnAb谱系中很常见，但传统疫苗没有很好地解决。初步数据 显示MEL在人CD 4 BS bnAb CH 103 UCA杂合dKI（HC+LC）中引发nAb应答的初步前景 KI）小鼠，其中“中靶”无反应性倾向B细胞对s-Env疫苗反应差。在目标1中，我们将建立在 这些发现通过使用共有Env MEL和混合Env MEL，结合选择性去除N-聚糖， 位置197以增加对CD 4结合位点的可及性，从而加速交叉中和抗体的引发 在黄金时期随后将使用MEL进行序贯加强。“助推器MEL”将是共识Envs，或 部分基于来自先前免疫的先前血清抗体的特异性结合而选择的那些，目的是 驱动B细胞对靶位点保守元件的亲和力成熟。为了进一步拓宽nAb 响应，我们将使用最近描述的方法，在多个物种中对融合肽（FP）进行eliminabnAb 包括老鼠。在该方法中，在CH 103 UCA het dKI小鼠中使用了初免-加强方案，该方案由FP-KLH初免和 MEL加强旨在“共同引发”CD 4 BS bnAb和FP bnAb。在目标2中，我们将测试类似的顺序MEL 免疫策略设计为在2F 5 KI小鼠中引发MPER定向的bnAb，其B细胞也受到更多的抑制。 显著的无反应性控制。因此，我们将使用强通用T辅助细胞表位作为进一步帮助破坏B的策略 细胞无反应性以最大化bnAb应答。这将涉及使用慢病毒载体用通用Th表位“预引发”。 疫苗载体（LVV）。最后，在目标3中，向下选择的m-Env疫苗候选物引发最佳nAb应答，并且 理想地，包括以最少的加强引发针对CD 4 BS、FP和MPER的nAb的实用方案，将用于 在完全多克隆系统中免疫，即兔和人源化IG基因座KI（Trianni）小鼠。创建基于m-Env的 能够引发针对关键疫苗靶标的交叉中和抗体的疫苗方案，特别是在人源化多克隆中， IG KI小鼠，应该会对HIV-1疫苗的开发产生重大影响。

Project Summary / Abstract A primary goal in HIV/AIDS vaccine development is to elicit broadly neutralizing antibodies (bnAbs) against the HIV-1 envelope glycoprotein spike that is anchored in the membrane (m-Env). To date, experimental vaccines have elicited mostly narrow, weak or non-neutralizing antibodies, typically using soluble Env (s-Env) molecules. Here, we will use membrane Env liposome (MEL) vaccines that incorporate well-ordered and stabilized m-Env trimers into liposomes via the transmembrane domain. MELs thus present a relevant conformation of Env in a multivalent manner and contain important epitopes of the membrane proximal external region (MPER) that are missing from s-Env vaccines. The creation of MELs has been made feasible by recent improvements to m-Env production by creation of high Env producer cells. Meanwhile, B cell anergy is common among HIV-1 bnAb lineages but is not well addressed by traditional vaccines. Preliminary data show initial promise of MELs in eliciting nAb responses in human CD4BS bnAb CH103 UCA heterozygous dKI (HC+LC KI) mice in which ‘on-target’ anergy prone B cells had responded poorly to s-Env vaccines. In Aim 1, we will build on these findings by using consensus Env MELs, and mixed Env MELs, combined with selective removal of N-glycan at position 197 to increase accessibility to the CD4 binding site in order to expedite elicitation of cross-neutralizing antibodies in the prime. This will be followed by sequential boosting with MELs. The ‘Booster MELs’ will be consensus Envs, or those selected in part based on specific binding by antecedent serum antibodies from prior immunization, with the intent to drive affinity maturation of B cells against conserved elements of the target site. In an effort to further broaden nAb responses, we will use an approach described recently that elicits bnAbs to the fusion peptide (FP) in multiple species including mice. In this approach, a prime-boost regimen in CH103 UCA het dKI mice consisting of an FP-KLH prime and MEL boosts is designed to “co-elicit” CD4BS bnAbs and FP bnAbs. In Aim 2, we will test a similar sequential MEL immunization strategy designed to elicit MPER-directed bnAbs in 2F5 KI mice, whose B-cells are also under more significant anergy controls. Hence, we will use strong universal T helper cell epitopes as a strategy to further help break B cell anergy to maximize bnAb responses. This will involve “pre-priming” with universal Th epitopes using a lentiviral vaccine vector (LVV). Finally, in Aim 3, down-selected m-Env vaccine candidates eliciting the best nAb responses, and ideally comprising practical regimens that elicit nAbs to CD4BS, FP and MPER with the least boosts, will be used to immunize in fully polyclonal systems, i.e. rabbits and humanized Ig locus KI (Trianni) mice. The creation of m-Env-based vaccine schemes able to elicit cross-neutralizing antibodies against key vaccine targets, particularly in humanized polyclonal Ig KI mice, should have a significant impact on HIV-1 vaccine development.