利用腺相關病毒表現中和抗體以預防新型冠狀病毒感染

Abstract

新型冠狀病毒 (SARS-CoV-2) 是一種高傳染力的冠狀病毒，主要透過上呼吸道黏膜感染人體，在2020年到2023年間對人類造成重大的影響，為此人類也發展出如小分子藥物、疫苗、單株抗體的策略以應對SARS-CoV-2的挑戰。其中，單株抗體可以直接中和病毒以抑制病毒感染，目前已有許多商業化單株抗體投入使用，其中一種單株抗體COV2-2130，在商業化的單株抗體中是相對廣效的，具有中和多個變異株的能力。因此為了在鼻腔黏膜產生對SARS-CoV-2的免疫力以預防感染，本研究將包裹COV2-2130抗體基因的腺相關病毒 (adeno-associated virus，AAV) 轉導到鼻腔，而且由於自然情況下鼻腔黏膜的抗體組成是dIgA (dimeric IgA) 的衍生物，為了瞭解抗體的類型 (class) 與構型 (conformation) 是否會影響中和能力，研究還將抗體以dIgA、mIgA (monomeric IgA)、IgG的形式表現；並檢驗鼻腔給予AAV之後是否能提供黏膜免疫 (mucosal immunity) 與全身免疫 (systemic immunity)。結果顯示在血液中dIgA、IgG組的小鼠可偵測到抗體表現，在mIgA組則觀察到較低的表現量；而這些抗體的中和能力與抗體表現量呈現高度一致。在鼻腔分泌物中則觀察到不一樣的現象，不論dIgA、mIgA、IgG組皆可以在鼻腔沖洗液中檢測到抗體表現，然而dIgA與IgG組相比，即使抗體表現量相近，dIgA組卻表現出更明顯的病毒抑制能力。透過AAV鼻腔轉導抗體基因可以在鼻腔分泌物與血液中偵測到這些功能性抗體的表現，說明這套系統具有提供黏膜免疫與全身免疫的潛力，期望未來能有更廣泛的利用。

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly contagious coronavirus that primarily infects human through the upper respiratory tract mucosa. It has had a significant impact on humans from 2020 to 2023. In response to the challenge, various strategies have been developed, including small molecule drugs, vaccines, and monoclonal antibodies. Monoclonal antibodies have the ability to directly neutralize the virus and inhibit viral infection. Currently, there are numerous commercial monoclonal antibodies, among which COV2-2130 is relatively broad-spectrum, capable of neutralizing multiple variants. Therefore, to generate immunity against SARS-CoV-2 in the nasal mucosa and prevent infection, this study employed adeno-associated virus (AAV) to deliver the COV2-2130 antibody gene in the nasal cavity. Since the main type of antibody in nasal mucosa is a derivative of dimeric IgA (dIgA), the study aimed to investigate whether the antibody class and conformation would affect its neutralizing capacity. To understand their impact, COV2-2130 were expressed in the forms of dIgA, monomeric IgA (mIgA), and IgG. The study also examined whether nasal administration of AAV could induce both mucosal immunity and systemic immunity. Results revealed detectable antibody expression in mice belonging to the dIgA and IgG groups in the blood, but lower expression was observed in the mIgA group. The neutralizing capacity of serum antibodies correlated significantly with their expression levels. While, distinct findings were observed in nasal secretions. Antibody expression was detectable in the nasal lavage fluid of all groups. However, despite similar expression levels, the dIgA group exhibited enhanced ability to inhibit viral activity compared to the IgG group. The expression of these functional antibodies can be detected in nasal secretions and blood by delivering antibody genes after AAV nasal administration. This indicates that the system has the potential to provide both mucosal and systemic immunity. We hope that this system can be more widely utilized in the future.