PDF(Pubmed)
Abstract：
The coronavirus papain-like protease (PLpro) is crucial for viral replicase polyprotein processing. Additionally, PLpro can subvert host defense mechanisms by its deubiquitinating (DUB) and deISGylating activities. To elucidate the role of these activities during SARS-CoV-2 infection, we introduced mutations that disrupt binding of PLpro to ubiquitin or ISG15. We identified several mutations that strongly reduced DUB activity of PLpro, without affecting viral polyprotein processing. In contrast, mutations that abrogated deISGylating activity also hampered viral polyprotein processing and when introduced into the virus these mutants were not viable. SARS-CoV-2 mutants exhibiting reduced DUB activity elicited a stronger interferon response in human lung cells. In a mouse model of severe disease, disruption of PLpro DUB activity did not affect lethality, virus replication, or innate immune responses in the lungs. This suggests that the DUB activity of SARS-CoV-2 PLpro is dispensable for virus replication and does not affect innate immune responses in vivo. Interestingly, the DUB mutant of SARS-CoV replicated to slightly lower titers in mice and elicited a diminished immune response early in infection, although lethality was unaffected. We previously showed that a MERS-CoV mutant deficient in DUB and deISGylating activity was strongly attenuated in mice. Here, we demonstrate that the role of PLpro DUB activity during infection can vary considerably between highly pathogenic coronaviruses. Therefore, careful considerations should be taken when developing pan-coronavirus antiviral strategies targeting PLpro.
摘要：
冠状病毒木瓜蛋白酶（PLpro）对于病毒复制酶多蛋白加工至关重要。此外,PLpro可以通过其去泛素化（DUB）和去分化活动来破坏宿主防御机制。为了阐明这些活动在SARS-CoV-2感染过程中的作用，我们引入了破坏PLpro与泛素或ISG15结合的突变.我们发现了一些突变，这些突变强烈降低了PLpro的DUB活性，不影响病毒多蛋白加工。相比之下,消除去糖基化活性的突变也阻碍了病毒多蛋白的加工，当引入病毒时，这些突变体是不可行的。表现出DUB活性降低的SARS-CoV-2突变体在人肺细胞中引起更强的干扰素应答。在严重疾病的小鼠模型中，PLproDUB活性的破坏不影响致死率，病毒复制，或肺部的先天免疫反应。这表明SARS-CoV-2PLpro的DUB活性对于病毒复制是可有可无的,并且不影响体内的先天免疫应答。有趣的是,SARS-CoV的DUB突变体在小鼠中复制至略低的滴度，并在感染早期引起免疫反应减弱，虽然杀伤力没有受到影响.我们先前表明，缺乏DUB和去糖基化活性的MERS-CoV突变体在小鼠中被强烈减弱。这里,我们证明PLproDUB活性在感染过程中的作用在高致病性冠状病毒之间可以有很大差异.因此,在开发针对PLpro的泛冠状病毒抗病毒策略时，应谨慎考虑。
