Antigenic properties of the V1/V2 domain of HIV-1 gp120

描述（由申请人提供）：尽管迫切需要艾滋病毒疫苗，但目前的疫苗方法取得的成功有限。我们已经表明，来源于原代病毒的许多Env对标准抗体中和的抗性的主要因素是V1/V2结构域掩蔽了敏感的中和靶标。这表明，通过更好地理解这种耐药机制，以及通过鉴定对这种阻断作用不敏感的其他免疫靶点，将有助于开发有效的疫苗。我们已经鉴定了原代HIV-1 Env的V2结构域中的一个特定区域，该区域是对几种mAb极其敏感的中和靶标。C108 g针对构象和聚糖依赖性V2表位，中和含有其表位的病毒，其效力比几乎任何其他已知抗体都大。2909针对在完整病毒体上特异性表达但不针对可溶性Env蛋白的四级表位，对SF 162和JR-FL变体具有甚至更强的中和活性。2909与病毒体的结合需要Env中存在V2和V3结构域。我们最近已经表明，2909表位的V3决定簇非常广泛，2909的类型特异性是由于V2中的残基需要精确地映射到与C108 g决定簇相同的区域。虽然这些单克隆抗体是类型特异性的，但C108 g和2909表位与共有进化枝B V2序列仅在单个残基处不同。这些单克隆抗体无与伦比的效力表明，它们与特别敏感的中和结构域结合，并表明这些表位的保守形式可能是重要的疫苗靶点。该提案将进一步绘制负责中和掩蔽的V1/V2决定簇，检查V1/V2结构域在自体中和中的作用，更完整地定义V2中介导有效中和的表位，分离和表征具有更广泛中和活性的其他V2特异性mAb，并确定此类Fab与适当V1/V2抗原之间形成的复合物的结构。最后，这些数据将被用来设计优化的miniproteins，目前的关键V2表位在高度免疫原性的形式，并测试这种免疫原诱导广泛中和抗体在几种动物模型的能力。

DESCRIPTION (provided by applicant): Despite the desperate need for an HIV vaccine, current approaches towards a vaccine has had limited success. We have shown that a major factor in the resistance of many Envs derived from primary viruses to neutralization by standard antibodies is masking of sensitive neutralization targets by the V1/V2 domain. This suggests that the development of an effective vaccine would be facilitated by a better understanding of this resistance mechanism, and by the identification of additional immune targets that are not susceptible to such blocking effects. We have identified a particular region in the V2 domain of primary HIV-1 Envs that is an extremely sensitive neutralization target to several mAbs. C108g, directed against a conformational and glycan-dependent V2 epitope, neutralizes viruses containing its epitope with greater potency than that of almost any other known antibody. 2909, directed against a quaternary epitope specifically expressed on intact virions but not soluble Env proteins, possesses even more potent neutralizing activity for SF162 and a JR-FL variant. 2909 binding to virions requires the presence of both the V2 and V3 domains in Env. We have recently shown that the V3 determinants of the 2909 epitope are very broad, and that the type-specificity of 2909 is due to the requirement for residues in V2 that map to precisely the same region as the C108g determinants. Although these mAbs are type-specific, both the C108g and 2909 epitopes differ from the consensus clade B V2 sequence only at single residues. The unrivalled potency of these mAbs argues that they bind to a particularly sensitive neutralization domain, and suggests that conserved forms of these epitopes could be important vaccine targets. This proposal will further map V1/V2 determinants responsible for neutralization masking, examine the role of the V1/V2 domain in autologous neutralization, more completely define epitopes in V2 that mediate potent neutralization, isolate and characterize additional V2- specific mAbs with broader neutralizing activities and determine the structures of complexes formed between such Fabs and appropriate V1/V2 antigens. Finally, this data will be used to design optimized miniproteins that present the critical V2 epitopes in highly immunogenic forms and to test the ability of such immunogens to induce broadly neutralizing antibodies in several animal models.