Elicitation of structure-specific antibodies by epitope scaffolds
Elicitation of structure-specific antibodies by epitope scaffolds
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DOI：
10.1073/pnas.1004728107
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发表时间：
2010-10-19
影响因子：
11.1
通讯作者：
Kwong, Peter D.
中科院分区：
文献类型：
--
作者：
Ofek, Gilad;Guenaga, F. Javier;Kwong, Peter D.
在天然环境中，针对免疫隐性、隐蔽或瞬时的靶点诱导抗体产生一直是疫苗设计的一个挑战。在此，我们展示了针对广泛中和抗体2F5的HIV - 1 gp41表位诱导产生结构特异性抗体。gp41的这个构象灵活的区域大多呈螺旋构象，但在与抗体2F5结合时会呈现一种弯曲的伸展结构。运用计算技术将2F5表位移植到选定的受体支架上。由此产生的“2F5 - 表位支架”对抗体2F5具有纳摩尔亲和力，并且具有一系列表位灵活性和抗原特异性。对具有最高亲和力和抗原区分能力的表位支架进行晶体学表征，分别证实了在游离态和与2F5结合态下，gp41分子移植物的目标构象达到了良好至近乎完美的程度。用2F5 - 表位支架免疫的动物显示出与移植物灵活性相关的移植物特异性免疫反应水平（p < 0.04），而针对移植物（通过丙氨酸替代逐个残基剖析）的抗体反应比用柔性或环化肽诱导产生的血清更接近2F5的反应，异源初免 - 加强免疫进一步增强了这种相似性。最后，由2F5 - 表位支架诱导产生的单克隆抗体与gp41肽形成的复合物的晶体结构显示，诱导产生的抗体使gp41呈现出其被2F5识别的形状。因此，表位支架提供了一种诱导产生识别预定目标形状和序列的抗体的方法，即使该形状在本质上是瞬时的，同时也提供了一种剖析影响这种诱导的因素的方法。
Elicitation of antibodies against targets that are immunorecessive, cryptic, or transient in their native context has been a challenge for vaccine design. Here we demonstrate the elicitation of structure-specific antibodies against the HIV-1 gp41 epitope of the broadly neutralizing antibody 2F5. This conformationally flexible region of gp41 assumes mostly helical conformations but adopts a kinked, extended structure when bound by antibody 2F5. Computational techniques were employed to transplant the 2F5 epitope into select acceptor scaffolds. The resultant "2F5-epitope scaffolds" possessed nanomolar affinity for antibody 2F5 and a range of epitope flexibilities and antigenic specificities. Crystallographic characterization of the epitope scaffold with highest affinity and antigenic discrimination confirmed good to near perfect attainment of the target conformation for the gp41 molecular graft in free and 2F5-bound states, respectively. Animals immunized with 2F5-epitope scaffolds showed levels of graft-specific immune responses that correlated with graft flexibility (p < 0.04), while antibody responses against the graft-as dissected residue-by-residue with alanine substitutions-resembled more closely those of 2F5 than sera elicited with flexible or cyclized peptides, a resemblance heightened by heterologous prime-boost. Lastly, crystal structures of a gp41 peptide in complex with monoclonal antibodies elicited by the 2F5-epitope scaffolds revealed that the elicited antibodies induce gp41 to assume its 2F5-recognized shape. Epitope scaffolds thus provide a means to elicit antibodies that recognize a predetermined target shape and sequence, even if that shape is transient in nature, and a means by which to dissect factors influencing such elicitation.