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。我们已经证明，许多原代病毒衍生的env对标准抗体的中和产生抗性的一个主要因素是V1/V2结构域掩盖了敏感的中和靶标。这表明，更好地了解这种耐药性机制，并确定不容易受到这种阻断效应影响的其他免疫靶点，将有助于开发有效的疫苗。我们已经在原发HIV-1 Envs的V2结构域中发现了一个特殊的区域，该区域对几种单克隆抗体是一个极其敏感的中和靶点。C108g针对构象和聚糖依赖的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要大。2909靶向在完整病毒粒子上特异性表达的四元表位，但不溶性Env蛋白，对SF162和JR-FL变体具有更强的中和活性。2909与病毒粒子的结合需要在Env中同时存在V2和V3结构域。我们最近表明2909表位的V3决定因子非常广泛，并且2909的类型特异性是由于V2中的残基需要精确地映射到与C108g决定因子相同的区域。尽管这些单克隆抗体具有类型特异性，但C108g和2909表位仅在单个残基上与共识的进化支B V2序列不同。这些单克隆抗体无与伦比的效力表明，它们与一个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决定因子，检查V1/V2结构域在自身中和中的作用，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额外V2特异性单克隆抗体，并确定这些单克隆抗体与适当的V1/V2抗原之间形成的复合物的结构。最后，这些数据将用于设计优化的微蛋白，以高度免疫原的形式呈现关键的V2表位，并在几种动物模型中测试这些免疫原诱导广泛中和抗体的能力。

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.