人巨细胞病毒自然感染过程中体液免疫应答机制研究

人巨细胞病毒（HCMV）在人群中普遍感染且潜伏多年，机体免疫功能低下人群的新发或复发感染将引起致命疾病。由于缺乏动物模型及完整病毒蛋白抗原，HCMV诱导的中和抗体及病毒优势中和表位尚不清晰，多种疫苗的研制在临床实验中宣告失败。HCMV病毒自然感染者的体液免疫应答及病毒表面的优势中和表位尚待深入研究。在前期工作中，课题组建立了高效全人抗体筛选和PGM深度测序平台，从HCMV自然感染者中获得56株全人抗体，包含多株优势中和抗体。本研究将在此基础上获得6例HCMV自然感染者的特异全人抗体盘，揭示抗体的分子特征以及抗体功能与基因型的关系，鉴定出HCMV表面的优势中和表位，揭示抗原驱动下的抗体体细胞突变，分析突变抗体谱系复杂度与抗病毒功能的关系。本研究将深入认识HCMV自然感染过程中的体液免疫应答机制，获得的优势中和抗体谱系特征和识别的中和表位分布，对于HCMV治疗性抗体和疫苗的研发具有重要意义。

Human cytomegalovirus (HCMV) is capable of latent infection in humans, which causes serious and even life-threatening disease in human populations with immune suppression or immunocompromised patients. . Due to the lack of animal model and full antigens, the neutralizing antibodies induced by HCMV and predominant neutralizing epitopes on HCMV antigen remain elusive. As a result, there have been several experimental vaccines which are difficult to induce potent neutralization failed in human clinical trials. Understanding the humoral immune response to human cytomegalovirus during natural infection and the characterization of dominant neutralizing epitopes on HCMV antigen need to be addressed urgently.. In previous study, with efficient method on human antibody isolation and PGM deep sequencing, we have established a panel of 56 HCMV-specific monoclonal antibodies from natural infected healthy donors, most of which exhibited potent neutralizing activity. In this study, we will establish a larger panel of HCMV-specific monoclonal antibodies from six healthy subjects. Using these antibodies as probes, we will discover the relationship between antigen specificity and antibody function, and further identify the dominant neutralizing epitopes precisely. To investigate the somatic variants driven by antigen, we will analyze the correlation between the size and complexity of antibody lineages and their antiviral function. Our study provides extensive understanding on active evolution and mechanism of humoral response against HCMV. Furthermore, the lineage character of dominant neutralizing antibodies and the distribution of corresponding epitopes on HCMV antigen may play an important role for the development of therapeutic antibody and prophylaxis vaccine.