The coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged as a pandemic and has inflicted enormous damage on the lives of the people and economy of many countries worldwide. However, therapeutic agents against SARS-CoV-2 remain unclear. SARS-CoV-2 has a spike protein (S protein), and cleavage of the S protein is essential for viral entry. Nattokinase is produced by Bacillus subtilis var. natto and is beneficial to human health. In this study, we examined the effect of nattokinase on the S protein of SARS-CoV-2. When cell lysates transfected with S protein were incubated with nattokinase, the S protein was degraded in a dose- and time-dependent manner. Immunofluorescence analysis showed that S protein on the cell surface was degraded when nattokinase was added to the culture medium. Thus, our findings suggest that nattokinase exhibits potential for the inhibition of SARS-CoV-2 infection via S protein degradation.
由严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV-2) 引起的 2019 年冠状病毒病 (COVID-19) 已成为一种流行病，对全球许多国家的人民生活和经济造成了巨大损害。 然而，针对 SARS-CoV-2 的治疗剂仍不清楚。 SARS-CoV-2 具有刺突蛋白（S 蛋白），S 蛋白的切割对于病毒进入至关重要。 纳豆激酶由枯草芽孢杆菌变种产生。 纳豆对人体健康有益。 在这项研究中，我们检查了纳豆激酶对 SARS-CoV-2 的 S 蛋白的影响。 当用 S 蛋白转染的细胞裂解物与纳豆激酶一起孵育时，S 蛋白以剂量和时间依赖性方式降解。 免疫荧光分析表明，在培养基中加入纳豆激酶后，细胞表面的 S 蛋白被降解。 因此，我们的研究结果表明，纳豆激酶具有通过 S 蛋白降解抑制 SARS-CoV-2 感染的潜力。