Institute of Virology, Hannover Medical School, Hannover, Germany.
J Virol. 2011 Dec;85(24):13363-72. doi: 10.1128/JVI.05300-11. Epub 2011 Oct 12.
The highly pathogenic severe acute respiratory syndrome coronavirus (SARS-CoV) poses a constant threat to human health. The viral spike protein (SARS-S) mediates host cell entry and is a potential target for antiviral intervention. Activation of SARS-S by host cell proteases is essential for SARS-CoV infectivity but remains incompletely understood. Here, we analyzed the role of the type II transmembrane serine proteases (TTSPs) human airway trypsin-like protease (HAT) and transmembrane protease, serine 2 (TMPRSS2), in SARS-S activation. We found that HAT activates SARS-S in the context of surrogate systems and authentic SARS-CoV infection and is coexpressed with the viral receptor angiotensin-converting enzyme 2 (ACE2) in bronchial epithelial cells and pneumocytes. HAT cleaved SARS-S at R667, as determined by mutagenesis and mass spectrometry, and activated SARS-S for cell-cell fusion in cis and trans, while the related pulmonary protease TMPRSS2 cleaved SARS-S at multiple sites and activated SARS-S only in trans. However, TMPRSS2 but not HAT expression rendered SARS-S-driven virus-cell fusion independent of cathepsin activity, indicating that HAT and TMPRSS2 activate SARS-S differentially. Collectively, our results show that HAT cleaves and activates SARS-S and might support viral spread in patients.
高致病性严重急性呼吸综合征冠状病毒（SARS-CoV）对人类健康构成持续威胁。病毒刺突蛋白（SARS-S）介导宿主细胞进入，是抗病毒干预的潜在靶点。宿主细胞蛋白酶激活 SARS-S 对于 SARS-CoV 的感染性至关重要，但仍不完全清楚。在这里，我们分析了 II 型跨膜丝氨酸蛋白酶（TTSPs）人气道胰蛋白酶样蛋白酶（HAT）和跨膜蛋白酶丝氨酸 2（TMPRSS2）在 SARS-S 激活中的作用。我们发现 HAT 在替代系统和真实 SARS-CoV 感染的背景下激活 SARS-S，并且在支气管上皮细胞和肺细胞中与病毒受体血管紧张素转换酶 2（ACE2）共表达。HAT 通过突变和质谱法在 R667 处切割 SARS-S，并在顺式和反式激活 SARS-S 细胞-细胞融合，而相关的肺蛋白酶 TMPRSS2 在多个位点切割 SARS-S 并仅在反式激活 SARS-S。然而，只有 TMPRSS2 而不是 HAT 表达使 SARS-S 驱动的病毒-细胞融合不依赖于组织蛋白酶活性，表明 HAT 和 TMPRSS2 以不同的方式激活 SARS-S。总的来说，我们的结果表明 HAT 切割并激活 SARS-S，并且可能支持患者体内的病毒传播。
