人B组腺病毒中和抗体的作用机制研究

人腺病毒B组3、7、55型等是重要的致急性呼吸道感染病原体，中和抗体作用机制是腺病毒新型疫苗和抗体药物研发有待解决的基本问题。我们已证明人B组腺病毒中和抗体主要靶向六邻体，并获得多株抗六邻体中和单抗并人源化；但发现重组B组11型纤毛头免疫小鼠产生了高滴度型间交叉中和抗体，并制备了广谱中和单抗。我们推测重组五邻体基座等也可能诱导广谱中和抗体应答，靶向不同结构蛋白的中和抗体可能有独特的作用机制。本课题将表达人B组腺病毒多种结构蛋白，免疫动物制备多抗，以鉴定新的中和抗原；在已有单抗基础上，研发靶向新抗原的中和单抗，分析这些单抗阻断病毒吸附、内化、出内含体、转运或脱壳的方式，及抗原抗体结合的关键氨基酸和可能涉及的细胞蛋白，系统探讨靶向人B组腺病毒六邻体、纤毛、五邻体基座等中和抗体的作用机制，及可能的广谱作用机制。本研究将加深我们对腺病毒结构和免疫的认识，为新型疫苗和中和抗体药物研发奠定基础。

Human adenovirus (HAdV) types 3, 7, 55 of species B are important pathogens causing acute respiratory tract infection. The neutralization mechanism of antibody is the basic problem to be solved in the development of novel vaccines and antibody drugs for adenovirus. We found the neutralizing antibodies against HAdV-B mainly target the structure protein, hexon; and several neutralizing monoclonal antibodies (NMAb) against HAdV-3 or HAdV-7 hexon have been prepared and successfully humanized. But the neutralization mechanism of the antibodies against hexon is still unclear. We expressed and purified the fiber knob protein of HAdV-11 in E.coli which could induce high titer cross-neutralizing antibodies against several types of HAdV-B in mice. And several broad-spectrum NMAbs were obtained using this knob. So other recombinant structural proteins may also induce neutralizing antibody responses, and antibodies targeting the various structural proteins may neutralize HAdV by unique mechanisms. In this study, we will express a variety of recombinant structural proteins of HAdV-B, such as penton base, to identify more neutralizing antigens and cross-neutralizing antigens among different types. And the main neutralization mechanisms of antibodies against different structural proteins will be investigated. We will prepare more NMAbs against newly identified antigens, especially broad-spectrum NMAbs. The possible neutralization mechanisms of the our existing and novel NMAbs will be investigated by studying the process of NMAbs blocking virus adsorption, internalization and transport in cells, and analyzing the structure of antigen-antibody complex and the possible cellular proteins involved. This research will contribute to a better understanding of structure and protective immunity of HAdV-B, and provide a basis on the development of HAdV-B vaccines or neutralizing antibody medicines.