Targeting neutralizing antibody-defined sites on HIV gp41 for vaccine design

描述(由申请人提供)：HIV-1gp41包含高度保守的区域，是疫苗设计的有吸引力的目标。其中一个区域是gp41的膜近端外区(MPER)，与其结合的人类单抗(MAbs)2F5、4E10和Z13可以中和来自不同分支的HIV-1初级分离株。此外，gp41的N-七肽重复区(NHR)也是融合抑制药物和中和单抗的靶点。(在我们的初步研究中，我们已经确定了亲和力增强的Z13(Z13e1)版本，以及针对gp41的NHR区域诱导的兔单抗和人HIV-1中和单抗。) 由于gp41结构的异质性，以及对HIV-1 gp41上的中和表位的特殊结构和呈现方式的了解，很难获得针对gp41的广泛中和抗体。我们设计了一系列gp41模拟物，专门呈现gp41的MPER和NHR区的中和表位。这些gp41模拟物将用于免疫兔，并测定血清中和抗体效价，以确定最佳MPER和NHR先导免疫原(目标1)。为了更好地了解中和表位的免疫原性，将用噬菌体展示法回收针对这些表位的兔单抗，并分别检测其中和活性(目标2)。MAb面板将用于探测gp41模拟表位，然后将进行修饰，以便有利地展示中和表位，并封闭非中和表位(目标3)。此外，在合作努力中，将确定抗NHR区(兔和人)的单抗Z13e1和两个HIV-1中和单抗的结构(目标4)。通过这些方式，抗体对gp41的MPER和NHR区域的访问将得到准确的评估，这反过来应导致基于gp41的免疫原的改进，从而产生更有效的针对HIV-1的中和抗体。

DESCRIPTION (provided by applicant): HIV-1 gp41 contains highly conserved regions that are attractive targets for vaccine design. One such region is the membrane-proximal external region (MPER) of gp41, and the human monoclonal antibodies (mAbs) that bind to it, 2F5, 4E10 and Z13, neutralize primary isolates of HIV-1 from different clades. In addition, the N-heptad repeat (NHR) region of gp41 is a target of fusion inhibitor drugs and neutralizing mAbs. (In our preliminary studies, we have identified an affinity-improved version of Z13 (Z13e1), as well as rabbit mAbs and a human HIV-1 neutralizing mAb that were elicited against the NHR region of gp41.) Eliciting broadly neutralizing Abs against gp41 has been difficult due in part to heterogeneity in gp41 structure and a poor understanding of the specific structure and presentation of the neutralizing epitopes on HIV-1 gp41. We have designed a series of gp41 mimetics that specifically present the neutralizing epitopes of the MPER and NHR region of gp41. These gp41 mimetics will be used to immunize rabbits, and the serum neutralizing Ab titers measured to determine the best MPER and NHR lead immunogens (Aim 1). In order to gain more specific knowledge about the immunogenicity of the neutralizing epitopes, rabbit mAbs that were elicited to these epitopes will be rescued by phage display and tested individually for neutralizing activity (Aim 2). The mAb panels will be used to probe the gp41 mimetics, and then modifications will be introduced so as to favorably display the neutralizing epitopes and occlude the non-neutralizing ones (Aim 3). In addition, in a collaborative effort, structures of the mAb Z13e1 and two HIV-1 neutralizing mAbs against the NHR region (rabbit and human) will be determined (Aim 4). In these ways, antibody access to the MPER and NHR region of gp41 will be precisely evaluated, which in turn should lead to improved gp41-based immunogens that will elicit more potent neutralizing Abs against HIV-1.