Synthetic Variable Domain Glycopeptides for Neutralizing Epitope Characterization

描述（由申请方提供）：HIV-1包膜上广泛中和表位的鉴定和表征是设计有效HIV-1疫苗的重要步骤。最近，一类新的广泛中和抗体（bNAb），包括PG 9，PG 16和PGT类抗体，已从HIV感染的“精英控制者”中分离出来。这些bNAb以显著的广度和效力中和主要HIV-1菌株。这些bNAb的抗原识别的共同特征是它们都靶向gp 120的V1/V2和/或V3区的聚糖依赖性四级表位。最近的X-射线晶体结构研究表明，PG 9在V1/V2结构域的背景下与N160和N156处的N-聚糖结合，而PGT 128在V3结构域的背景下识别N322和N301位点的保守N-聚糖。然而，中和表位的精确性质，特别是N156和N301处N-聚糖的精细结构仍有待表征。HIV-1 gp 120糖基化的复杂性和异质性使表位的进一步定位变得复杂。我们推测，独特的V1/V2和V3糖肽构成这些bNAb的中和表位。为了验证这一假设，我们将进行两个具体目标中描述的实验。目的一是通过化学酶法设计并合成N-糖链连接在保守的N-糖基化位点上的HIV-1环状糖肽V1/V2和V3。目的2是通过与合成糖肽的结合和结构研究来表征中和抗体的抗原识别。此外，合成糖肽将用于检测HIV感染的“非进展者”血清中的聚糖依赖性、V1/V2和V3特异性中和抗体。这些研究可能为HIV-1疫苗设计提供重要见解。 与公共卫生的关系：艾滋病毒/艾滋病是一种严重的全球流行病，威胁着人类健康和社会稳定。拟议的研究旨在表征广泛中和抗体的中和表位，这将为HIV-1疫苗设计提供重要见解。

DESCRIPTION (provided by applicant): Identification and characterization of broadly neutralizing epitopes on the HIV-1 envelope are important steps in the design of an effective HIV-1 vaccine. Recently, a new class of broadly neutralizing antibodies (bNAbs), including PG9, PG16, and the PGT class antibodies, has been isolated from HIV-infected "elite controllers". These bNAbs neutralize primary HIV-1 strains with remarkable breadth and potency. A common feature of antigen recognition by these bNAbs is that they all target glycan-dependent quaternary epitopes at the V1/V2 and/or V3 regions of gp120. Recent X-ray crystal structural studies indicate that PG9 binds to N-glycans at N160 and N156 in the context of V1/V2 domain, and PGT128 recognizes conserved N-glycans at N322 and N301 sites in the context of V3 domain. However, the precise nature of the neutralizing epitopes, particularly the fine structures of the N-glycans at N156 and N301 remains to be characterized. Further mapping of the epitopes is complicated by the complexity and heterogeneity of glycosylation of HIV-1 gp120. We hypothesize that unique V1/V2 and V3 glycopeptides constitute the neutralizing epitopes for these bNAbs. To test this hypothesis, we will perform experiments described in two specific aims. Aim 1 is to design and synthesize cyclic V1/V2 and V3 HIV-1 glycopeptides with defined N-glycans being attached at the conserved N- glycosylation sites, by a novel chemoenzymatic method. Aim 2 is to characterize antigen recognition by the neutralizing antibodies through binding and structural studies with the synthetic glycopeptides. In addition, the synthetic glycopeptides will be used to detect glycan- dependent, V1/V2 and V3-specific neutralizing antibodies in sera from HIV-infected "non- progressors". These studies are likely to provide important insights for HIV-1 vaccine design. PUBLIC HEALTH RELEVANCE: HIV/AIDS is a serious global epidemic that threatens human health and social stability. The proposed research aims to characterize the neutralizing epitopes of broadly neutralizing antibodies, which will provide important insights in HIV-1 vaccine design.