Expediting elicitation of HIV-1 bnAbs with membrane Env vaccines

项目摘要/摘要 开发HIV/AIDS疫苗的一个主要目标是诱导针对HIV-1的广泛中和抗体(BNAbs) 膜上固定的包膜糖蛋白尖峰(m-env)。到目前为止，实验性疫苗已经引发了大部分 窄、弱或非中和抗体，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)疫苗将有序和稳定的m-Env三聚体通过 跨膜结构域。因此，MEL以多价方式呈现Env的相关构象，并包含重要的 S-env疫苗缺失的膜近端外区表位。MEL的创建 通过创建高环境容量的生产细胞，最近对m-Env生产进行了改进，使其成为可行的。同时， B细胞无能在HIV-1bNab谱系中很常见，但传统疫苗并不能很好地解决这一问题。初步数据 MEL在人CD4BS bNab CH103UCA杂合子DKI(HC+LC)中诱导NAB反应的初步前景 Ki)小鼠，在这些小鼠中，“靶向”无能倾向的B细胞对S环境病毒疫苗的反应很差。在目标1中，我们将在 这些发现是通过使用共识Env MEL和混合Env MEL，并结合选择性地去除N-糖链在 位置197以增加对CD4结合部位的可及性，以加快交叉中和抗体的激发 在黄金时期。这之后将使用MES进行顺序增强。《助推器梅尔斯》将成为共识的env，或者 部分基于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 推动B细胞对靶部位保守元件的亲和力成熟。为了进一步扩大NAB的范围 ，我们将使用最近描述的一种方法，在多个物种中诱导融合多肽(FP)的bNAbs 包括老鼠。在这种方法中，CH103UCA HET DKI小鼠的Prime-Boost方案由FP-KLH素和 MEL Boost被设计用来“共同诱导”CD4BS bNAbs和FP bNAbs。在目标2中，我们将测试类似的顺序MEL 在2F5Ki小鼠中诱导MPER导向的bNAb的免疫策略，其B细胞也处于 显著的无能控制。因此，我们将使用强大的通用T辅助细胞表位作为策略，进一步帮助打破B 细胞无能，以最大限度地提高bNab反应。这将包括使用慢病毒对通用Th表位进行预启动 疫苗载体(LVV)。最后，在目标3中，下调选择的m-Env候选疫苗可产生最佳的NAB反应，以及 理想情况下，包括对CD4BS、FP和MPER具有最小促进作用的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。基于m-Env的网络环境的创建 能够诱导针对关键疫苗靶点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.