嵌合型SARS-CoV-2中和性抗體之製備與功能分析

Development and Functional Characterization of the Chimeric SARS-CoV-2 Neutralizing Antibodies

張亭渝(Ting-Yu Chang)

指導教授 ： 張世宗

國立臺灣大學/生命科學院/生化科技學系/碩士(2022年)

https://doi.org/10.6342/NTU202202346

摘要

由新型冠狀病毒 (SARS-CoV-2) 導致的新型冠狀病毒肺炎 (COVID-19) 自2019年爆發至今仍在世界大流行中。而SARS-CoV-2中的棘蛋白 (Spike protein; S) 由S1亞基和S2亞基組成，並在受體結合及病毒與宿主細胞膜融合中扮演著最關鍵的角色。我們先前的研究發現有四種S2特異性鼠源單株抗體 (S2-4D、S2-5D、S2-8D和S2-4A) 能夠藉由阻斷病毒與宿主細胞膜融合進而有效中和SARS-CoV-2，並且得知S2-4D、S2-5D、S2-8D和S2-4A所結合的抗原表位位於S(1042-1167) 區域。本論文進一步確認了S2-4D、S2-5D、S2-8D和S2-4A的關鍵結合位點位於棘蛋白的E1144、F1148、L1152和F1156。接著，抽取這四種S2特異性單株抗體之融合瘤細胞的mRNA，進行次世代基因定序，以解析抗體重鏈和輕鏈的基因序列。將S2-4A和S2-8D之重鏈和輕鏈變異區的DNA序列接到含有人類IgG1重鏈和Kappa輕鏈恆定區的質體中，再將質體轉染至Expi293F細胞以生產嵌合型S2-4A和S2-8D抗體，並將其命名為ChS2-4A和ChS2-8D。利用酵素連結免疫吸附分析法及西方墨點法，證實ChS2-4A和ChS2-8D可專一性的辨認棘蛋白和S2-8D與S2-4A的抗原表位片段。在病毒斑抑制中和試驗中，證實ChS2-4A和ChS2-8D具有中和Wild type、Delta、Omicron BA.2之SARS-CoV-2病毒株的能力。

關鍵字

新型冠狀病毒 ； 新型冠狀病毒肺炎 ； 棘蛋白 ； 單株抗體 ； 次世代基因定序 ； 嵌合型抗體

並列摘要

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has spread worldwide for causing the pandemic of the emerging coronavirus disease 2019 (COVID-19). The SARS-CoV-2 spike (S) protein, composed of S1 subunit and S2 subunit, plays the most crucial roles in receptor binding and virus-host cell membrane fusion. In our previous study, four S2-specific mouse monoclonal antibodies (mAbs) (S2-4D, S2-5D, S2-8D and S2-4A) have been demonstrated with SARS-CoV-2 neutralizing activities through blocking the virus-host cell membrane fusion. The binding epitopes of S2-4D, S2-5D, S2-8D and S2-4A are located within the region of S(1042-1167). Here I further identified that E1144, F1148, L1152 and F1156 of S(1042-1167) are the essential antigenic determinants for efficient binding by S2-4D, S2-5D, S2-8D and S2-4A. The mRNAs from the hybridoma cell lines which can produce S2-4D, S2-5D, S2-8D and S2-4A were extracted for performing the next-generation sequencing (NGS). The DNA sequences encoding for the heavy chain and light chain variable domains of S2-8D and S2-4A were cloned into the plasmids to fuse with the constant regions of the human IgG1 heavy chain and kappa light chain, respectively. The plasmids were co-transfected to Expi293F cells for expression of the chimeric S2-8D and S2-4A mAbs (referred to as ChS2-8D and ChS2-4A). ChS2-8D and ChS2-4A can specifically identify spike protein and the epitope fragments of S2-8D and S2-4A. The results of the plaque reduction neutralization test (PRNT) showed that ChS2-8D and ChS2-4A can neutralize the SARS-CoV-2 virus strains of wild type, Delta, and Omicron BA.2.

並列關鍵字

SARS-CoV-2 ； Coronavirus disease 2019 (COVID-19) ； Spike protein ； Monoclonal antibody ； Next-generation sequencing (NGS) ； Antibody humanization

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