CONSTRAINED HIV1 GP41 ELDKWA PEPTIDES FOR AIDS VACCINES

描述：(改编自申请人的摘要)提出了一种跨学科的方法来鉴定构象受限制的多肽作为免疫原，将引起对艾滋病的保护性免疫。这一方法将基于已知的单抗2F5广泛的HIV-1中和活性，它识别高度保守的氨基酸序列ELDKWA，对应于HXB2病毒包膜糖蛋白gp41的662-667残基。需要检验的假设是，构象受限的多肽，旨在模拟ELDKWA表位的天然或2F5结合构象，当它们与合适的载体蛋白或多价合成呈递系统结合时，将诱导高水平的中和抗体。由于这些构象可能接近2F5结合的ELDKWA构象，因此将探索一系列旨在有利于β-折叠、β-转折或β-芽的半胱氨酸桥肽。该多肽系列将用于优化2F5表位的环大小和位置。在另一系列多肽中，将研究结合α-甲基取代以产生局部骨架约束的线性GP-41片段，以定位潜在的螺旋或β转角结构。第三系列类似物将测试模仿gp41中ELDKWA侧翼区域可能的自然构象的螺旋锁定多肽。然后，第二个设计周期将结合最有力的约束功能。对人类鼻病毒/ELDKWA嵌合体组合文库的单独、平行研究获得的新的结构洞察力也将被纳入。所有合成肽都将被检测与2F5的亲和力和HIV免疫球蛋白(HIVIG)。选定的多肽将在豚鼠身上检测其免疫原性，评估为抗肽豚鼠血清滴度，并测试这些豚鼠抗血清对T细胞系适应(TCLA)和HIV-1原代分离株的中和效力。几个最有效的多肽的溶液构象也将通过圆二色谱和质子核磁共振光谱进行详细的表征。这些研究应该有助于阐明2F5样中和免疫反应的结构要求。载体结合、高度限制的ELDKWA多肽本身可能会引起强大的中和免疫反应。研究人员的结构-活性数据也应该指导开发新的类似2F5的HIV-1中和单抗，以及可能用作活疫苗的有效的人鼻病毒/HIV-1嵌合体。

DESCRIPTION: (Adapted from Applicant's Abstract) An interdisciplinary approach towards the identification of conformationally constrained peptides as immunogens that will elicit protective immunity against AIDS is proposed. This approach will be based on the known broad HIV-1 neutralizing activity of the monoclonal antibody 2F5, which recognizes the highly conserved amino-acid sequence ELDKWA, corresponding to residues 662-667 of the HXB2 viral envelope glycoprotein, gp41. The hypothesis to be tested is that conformationally constrained peptides, designed to mimic the native or 2F5-bound conformations of the ELDKWA epitope, will elicit high tiers of neutralizing antibodies when they are conjugated to a suitable carrier protein or multivalent synthetic presentation system. A series of cystine-bridge peptides designed to favor beta-sheets, beta-turns or beta-budges will be explored, since these conformations may approximate the 2F5-bound ELDKWA conformation. This peptide series will be used to optimize the loop size and position of the 2F5 epitope. In another series of peptides, linear gp-41 fragments that incorporate alpha-methyl substitutions to produce local backbone constraints will be studied, in order to locate potential helical or beta-turn structures. A third series of analogues will test helix-locked peptides that mimic the likely native conformation of the ELDKWA- flanking regions in gp41. A second design cycle will then combine the most potent constraining features. New structural insights obtained from separate, parallel studies of combinatorial libraries of human rhinovirus/ELDKWA chimeras will also be incorporated. All synthetic peptides will be assayed for affinity to 2F5 and for HIV immunoglobulin (HIVIG). Selected peptides will then be assayed for their immunogenic potency in guinea pigs, assessed as the anti- peptide guinea-pig serum titer, and the neutralizing potency of these guinea pig antisera tested against T-cell-line-adapted (TCLA) and primary HIV-1 isolates. The solution conformations of several of the most potent peptides will also be characterized in detail by circular dichroism and proton-NMR spectroscopy. These studies should shed light on the structural requirements for 2F5-like neutralizing immune responses. Carrier-conjugated, highly constrained ELDKWA peptides may elicit, by themselves, a potent neutralizing immune response. The investigator's structure-activity data should also guide the development of new 2F5-like, HIV-1- neutralizing MAbs, and potent human rhinovirus/HIV-1 chimeras of potential use as live vaccines.