Human viruses possess very complex supramolecular structures. Both icosahedral and enveloped viruses typically display an array of viral-encoded protein antigens at varied spatial densities on the viral particle surface. The viral nucleic acid genome, on the other hand, is encapsulated inside the viral particle. Although both the surface antigen and the interior nucleic acids could independently produce immunological responses, how B cells integrate these two types of signals and respond to a typical virus particle to initiate activation is not well understood at a molecular level. The study of these fundamental biological processes would benefit from the development of viral structural mimics that are well constructed to incorporate both quantitative and qualitative viral features for presentation to B cells. These novel tools would enable researchers to systematically dissect the underlying processes. Here we report the development of such particulate antigens based on liposomes engineered to display a model protein antigen, hen egg lysozyme (HEL). We developed methods to overexpress and purify various affinity mutants of HEL from E. coli. We conjugated the purified recombinant HEL proteins onto the surface of a virion-sized liposome in an orientation-specific manner at defined spatial densities and also encapsulated nucleic acid molecules into the interior of the liposome. Both the chemical conjugation of the HEL antigen on liposome surfaces and the encapsulation of nucleic acids were stable under physiologically relevant conditions. These liposomes elicited antigen-specific B-cell responses in vitro, which validate these supramolecular structures as a novel and effective approach to mimic and systematically isolate the role of essential viral features in directing the B-cell response to particulate antigens.

中文翻译：

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用于研究对感染和疫苗免疫反应的生物病毒合成脂质体模拟物。

人类病毒具有非常复杂的超分子结构。二十面体病毒和包膜病毒都通常在病毒颗粒表面以不同的空间密度显示一系列病毒编码的蛋白抗原。另一方面，病毒核酸基因组被封装在病毒颗粒内部。尽管表面抗原和内部核酸都可以独立产生免疫反应，但是在分子水平上，B细胞如何整合这两种信号并响应典型的病毒颗粒以启动激活尚不清楚。这些基本生物学过程的研究将受益于病毒结构模拟物的开发，该结构物构造得很好，可以结合定量和定性的病毒特征以呈递给B细胞。这些新颖的工具将使研究人员能够系统地解剖潜在过程。在这里，我们报道了基于脂质体的此类微粒抗原的开发，该脂质体经过工程改造以展示模型蛋白抗原，即鸡蛋溶菌酶（HEL）。我们开发了从大肠杆菌中过表达和纯化HEL的各种亲和突变体的方法。我们以定向特异性的方式在限定的空间密度下将纯化的重组HEL蛋白缀合到病毒体大小的脂质体的表面上，并且还将核酸分子封装到脂质体内。HEL抗原在脂质体表面的化学结合和核酸的封装在生理相关条件下均稳定。这些脂质体在体外引发了抗原特异性B细胞反应，