Division of HIV/AIDS and Sex-transmitted Virus Vaccines, Institute for Biological Product Control, National Institutes for Food and Drug Control (NIFDC), Beijing, People's Republic of China.
National Vaccine & Serum Institute, Beijing, People's Republic of China.
Emerg Microbes Infect. 2022 Dec;11(1):182-194. doi: 10.1080/22221751.2021.2014284.
The ubiquitously-expressed proteolytic enzyme furin is closely related to the pathogenesis of SARS-CoV-2 and therefore represents a key target for antiviral therapy. Based on bioinformatic analysis and pseudovirus tests, we discovered a second functional furin site located in the spike protein. Furin still increased the infectivity of mutated SARS-CoV-2 pseudovirus in 293T-ACE2 cells when the canonical polybasic cleavage site (682-686) was deleted. However, K814A mutation eliminated the enhancing effect of furin on virus infection. Furin inhibitor prevented infection by 682-686-deleted SARS-CoV-2 in 293T-ACE2-furin cells, but not the K814A mutant. K814A mutation did not affect the activity of TMPRSS2 and cathepsin L but did impact the cleavage of S2 into S2' and cell-cell fusion. Additionally, we showed that this functional furin site exists in RaTG13 from bat and PCoV-GD/GX from pangolin. Therefore, we discovered a new functional furin site that is pivotal in promoting SARS-CoV-2 infection.
普遍表达的蛋白水解酶弗林与 SARS-CoV-2 的发病机制密切相关，因此是抗病毒治疗的关键靶点。基于生物信息学分析和假病毒检测，我们在刺突蛋白中发现了第二个功能性弗林位点。当经典的多碱性切割位点（682-686）缺失时，弗林仍能增加突变的 SARS-CoV-2 假病毒在 293T-ACE2 细胞中的感染性。然而，K814A 突变消除了弗林对病毒感染的增强作用。弗林抑制剂可阻止 293T-ACE2-弗林细胞中 682-686 缺失的 SARS-CoV-2 的感染，但不能阻止 K814A 突变体。K814A 突变不影响 TMPRSS2 和组织蛋白酶 L 的活性，但影响 S2 切割成 S2'和细胞-细胞融合。此外，我们表明，这个功能性弗林位点存在于蝙蝠的 RaTG13 和穿山甲的 PCoV-GD/GX 中。因此，我们发现了一个促进 SARS-CoV-2 感染的新的功能性弗林位点。
