Heterologous epitope-scaffold prime:boosting immuno-focuses B cell responses to the HIV-1 gp41 2F5 neutralization determinant.
Heterologous epitope-scaffold prime:boosting immuno-focuses B cell responses to the HIV-1 gp41 2F5 neutralization determinant.
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DOI：
10.1371/journal.pone.0016074
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发表时间：
2011-01-26
期刊：
影响因子：
3.7
通讯作者：
Wyatt RT
中科院分区：
文献类型：
--
作者：
Guenaga J;Dosenovic P;Ofek G;Baker D;Schief WR;Kwong PD;Karlsson Hedestam GB;Wyatt RT
HIV - 1包膜糖蛋白（Env）gp120和gp41介导病毒进入，并且是中和抗体的作用靶点。在gp41中，由广泛中和抗体2F5所确定的一个连续表位是功能性HIV Env刺突上少数几个抗体可接近的保守位点之一。最近，作为基于结构指导设计的初步尝试，我们将2F5表位移植到几种非HIV受体支架蛋白上，我们将这些蛋白称为表位支架（ES）。作为免疫原，这些ES蛋白引发的抗体具有与2F5抗体相匹配的精细结合特异性。这些新型的2F5表位支架为我们提供了测试异源初免∶加强免疫策略的机会，以选择性地增强针对植入的gp41 2F5表位的抗体反应。这种策略可用于靶向HIV - 1 Env上保守但免疫原性差的位点，并且更普遍地，可用于其他结构明确的病原体靶点。在此，我们通过酶联免疫吸附测定（ELISA）测量表位特异性血清抗体滴度以及通过酶联免疫斑点分析（ELISpot）使用游离的2F5肽和一种不相关的ES蛋白作为探针来评估B细胞反应，从而对ES初免∶加强免疫进行评估。我们发现异源ES初免∶加强免疫方案引发了针对结构受限的2F5表位靶点的交叉反应性体液反应，并且在免疫原中加入混杂的T细胞辅助表位导致针对2F5移植表位的抗体滴度更高，但未产生病毒中和作用。有趣的是，两种表位支架（ES1和ES2）自身不能引发可检测到的2F5表位特异性反应，但在以ES5作为初免时可增强这种反应。总之，这些结果表明异源ES初免∶加强免疫方案有效地将体液免疫反应聚焦于结构明确且在免疫原中保守的HIV - 1 2F5表位。
The HIV-1 envelope glycoproteins (Env) gp120 and gp41 mediate entry and are the targets for neutralizing antibodies. Within gp41, a continuous epitope defined by the broadly neutralizing antibody 2F5, is one of the few conserved sites accessible to antibodies on the functional HIV Env spike. Recently, as an initial attempt at structure-guided design, we transplanted the 2F5 epitope onto several non-HIV acceptor scaffold proteins that we termed epitope scaffolds (ES). As immunogens, these ES proteins elicited antibodies with exquisite binding specificity matching that of the 2F5 antibody. These novel 2F5 epitope scaffolds presented us with the opportunity to test heterologous prime∶boost immunization strategies to selectively boost antibody responses against the engrafted gp41 2F5 epitope. Such strategies might be employed to target conserved but poorly immunogenic sites on the HIV-1 Env, and, more generally, other structurally defined pathogen targets. Here, we assessed ES prime∶boosting by measuring epitope specific serum antibody titers by ELISA and B cell responses by ELISpot analysis using both free 2F5 peptide and an unrelated ES protein as probes. We found that the heterologous ES prime∶boosting immunization regimen elicits cross-reactive humoral responses to the structurally constrained 2F5 epitope target, and that incorporating a promiscuous T cell helper epitope in the immunogens resulted in higher antibody titers against the 2F5 graft, but did not result in virus neutralization. Interestingly, two epitope scaffolds (ES1 and ES2), which did not elicit a detectable 2F5 epitope-specific response on their own, boosted such responses when primed with the ES5. Together, these results indicate that heterologous ES prime∶boost immunization regimens effectively focus the humoral immune response on the structurally defined and immunogen-conserved HIV-1 2F5 epitope.
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