Hajishengallis G, Hollingshead S K, Koga T, Russell M W
Department of Microbiology, University of Alabama at Birmingham 35294, USA.
J Immunol. 1995 May 1;154(9):4322-32.
The generation of secretory IgA Abs for specific immune protection of mucosal surfaces depends on stimulation of the mucosal immune system, but this is not effectively achieved by parenteral or even oral administration of most soluble Ags. To harness the exceptional mucosal immunogenicity of cholera toxin (CT), which is largely attributed to the cell-binding property of its B subunit, for the generation of other oral vaccines, we have genetically replaced the toxic A1 subunit of CT with a 42-kDa segment of a streptococcal protein adhesin. This construct was expressed in Escherichia coli as a chimeric protein that retained the GM1 ganglioside-binding activity of CT subunit B and the antigenicity of the streptococcal adhesin, as shown by GM1-ELISA developed with Abs to the steptococcal segment. The protein composition of chromatographically purified chimeric protein was verified by SDS-PAGE and Western blotting with Abs to both antigenic components of the construct. Peroral administration of this chimeric immunogen in mice elicited high levels of mucosal IgA and serum IgG Abs to the streptococcal adhesin, which persisted for at least 6 mo. This strategy allows the development of similar constructs from other candidate Ags for oral immunization against a variety of mucosally acquired infections.
分泌型IgA抗体的产生对于黏膜表面的特异性免疫保护至关重要，这依赖于黏膜免疫系统的刺激，但通过肠胃外甚至口服大多数可溶性抗原并不能有效地实现这一点。为了利用霍乱毒素（CT）卓越的黏膜免疫原性（这在很大程度上归因于其B亚基的细胞结合特性）来研发其他口服疫苗，我们已通过基因工程手段，用一种链球菌蛋白黏附素的42 kDa片段替换了CT的毒性A1亚基。这种构建体在大肠杆菌中表达为一种嵌合蛋白，它保留了CT亚基B的GM1神经节苷脂结合活性以及链球菌黏附素的抗原性，这通过用针对链球菌片段的抗体开展的GM1 - ELISA得以证实。通过SDS - PAGE以及用针对构建体两种抗原成分的抗体进行蛋白质印迹分析，验证了经色谱纯化的嵌合蛋白的蛋白质组成。在小鼠中经口给予这种嵌合免疫原可引发针对链球菌黏附素的高水平黏膜IgA和血清IgG抗体，且这些抗体至少持续6个月。该策略使得能够从其他候选抗原开发类似的构建体，用于口服免疫以抵御多种经黏膜感染。
