Virus & Immunity Unit, Institut Pasteur, Université de Paris Cité, CNRS UMR 3569, Paris, France.
Structural Virology Unit, Institut Pasteur, Université de Paris Cité, CNRS UMR 3569, Paris, France.
Nature. 2023 Dec;624(7990):207-214. doi: 10.1038/s41586-023-06761-7. Epub 2023 Oct 25.
Four endemic seasonal human coronaviruses causing common colds circulate worldwide: HKU1, 229E, NL63 and OC43 (ref. ). After binding to cellular receptors, coronavirus spike proteins are primed for fusion by transmembrane serine protease 2 (TMPRSS2) or endosomal cathepsins. NL63 uses angiotensin-converting enzyme 2 as a receptor, whereas 229E uses human aminopeptidase-N. HKU1 and OC43 spikes bind cells through 9-O-acetylated sialic acid, but their protein receptors remain unknown. Here we show that TMPRSS2 is a functional receptor for HKU1. TMPRSS2 triggers HKU1 spike-mediated cell-cell fusion and pseudovirus infection. Catalytically inactive TMPRSS2 mutants do not cleave HKU1 spike but allow pseudovirus infection. Furthermore, TMPRSS2 binds with high affinity to the HKU1 receptor binding domain (Kd 334 and 137 nM for HKU1A and HKU1B genotypes) but not to SARS-CoV-2. Conserved amino acids in the HKU1 receptor binding domain are essential for binding to TMPRSS2 and pseudovirus infection. Newly designed anti-TMPRSS2 nanobodies potently inhibit HKU1 spike attachment to TMPRSS2, fusion and pseudovirus infection. The nanobodies also reduce infection of primary human bronchial cells by an authentic HKU1 virus. Our findings illustrate the various evolution strategies of coronaviruses, which use TMPRSS2 to either directly bind to target cells or prime their spike for membrane fusion and entry.
四种地方性季节性人冠状病毒（HCoV）可引起普通感冒，在全球范围内流行：HKU1、229E、NL63 和 OC43（参考文献）。冠状病毒的刺突蛋白与细胞受体结合后，通过跨膜丝氨酸蛋白酶 2（TMPRSS2）或内体组织蛋白酶进行融合前的激活。NL63 使用血管紧张素转换酶 2（ACE2）作为受体，而 229E 使用人类氨肽酶 N。HKU1 和 OC43 的刺突通过 9-O-乙酰化唾液酸结合细胞，但它们的蛋白受体仍不清楚。在这里，我们表明 TMPRSS2 是 HKU1 的功能性受体。TMPRSS2 触发 HKU1 刺突介导的细胞-细胞融合和假病毒感染。无催化活性的 TMPRSS2 突变体不能切割 HKU1 刺突，但允许假病毒感染。此外，TMPRSS2 与 HKU1 受体结合域具有高亲和力（HKU1A 和 HKU1B 基因型的 Kd 值分别为 334 和 137 nM），但与 SARS-CoV-2 不结合。HKU1 受体结合域中的保守氨基酸对于与 TMPRSS2 的结合和假病毒感染是必需的。新设计的抗 TMPRSS2 纳米抗体可有效抑制 HKU1 刺突与 TMPRSS2 的附着、融合和假病毒感染。纳米抗体还降低了真实 HKU1 病毒对原代人支气管细胞的感染。我们的研究结果说明了冠状病毒的各种进化策略，这些策略利用 TMPRSS2 直接结合靶细胞或对其刺突进行融合前的激活，以实现膜融合和进入。
