新型冠状病毒入侵的宿主因子及潜在抗病毒药物研究进展

新型冠状病毒（SARS-CoV-2）是一种新发高传染性的冠状病毒。因其编码有限的病毒蛋白,SARS-CoV-2需要借助多种宿主因子完成其生命周期,而大多数参与其中的宿主因子及作用机理仍不明确。因此,研究参与SARS-CoV-2复制周期的宿主因子及作用机理,将有助于我们对病毒生命周期的认识及寻找抗SARS-CoV-2药物的作用靶点,从而可以帮助人们更加有效地防控新冠疫情。本文归纳了参与SARS-CoV-2复制周期中入侵的宿主因子,对全面理解SARS-CoV-2致病的分子机制、病毒感染的快速诊断及抗病毒新药研发具有重要的意义。     

SARS-CoV-2病毒以广泛存在且分化不同的动物源性ACE2为受体

正新型冠状病毒肺炎疫情对全球造成了史无前例的公共健康威胁和经济危机。尽管目前推测蝙蝠和穿山甲可能是导致新型冠状病毒肺炎的病原体SARS-CoV-2病毒的天然宿主,但其来源和为何突然暴发仍然是一个谜。但令人惊奇的是,与蝙蝠和穿山甲体内发现的SARS-CoV-2样冠状病毒不同,SARS-CoV-2病毒糖蛋白刺突(S)上有一个多元furin蛋白切割序列。SARS-CoV-2病毒利用人体内血管紧张素转换酶2(ACE2)作为受体侵染细胞。     

干扰素刺激基因与新型冠状病毒相互作用的研究进展

目前新型冠状病毒(severe acute respiratory syndrome coronavirus 2, SARS-CoV-2)感染所致的新型冠状病毒肺炎(corona virus disease, COVID-19)已成为威胁人类健康和安全的全球性流行性疾病。随着新突变株的不断出现,寻找有效治疗药物和靶点迫在眉睫。干扰素刺激基因(interferon-stimulated genes, ISGs)是由干扰素(interferons, IFNs)诱导后表达上调的一类基因,在宿主抵抗病毒感染过程中发挥着至关重要的作用。研究表明,ISGs能够靶向许多病毒复制的不同阶段发挥抗病毒作用,然而SARS-CoV-2也进化出各种策略干扰或逃避宿主天然免疫。因此,全面了解SARS-CoV-2与ISGs相互作用,对于设计抗病毒策略至关重要。本文简要综述不同ISGs抵抗SARS-CoV-2的作用机制,为开发新型的抗病毒药物提供思路和理论依据。     

冠状病毒对天然免疫的抑制作用

由严重急性呼吸综合征冠状病毒2(severe acute respiratory syndrome coronavirus 2, SARS-CoV-2)引起的新型冠状病毒肺炎(corona virus disease 2019, COVID-19),至今仍在全球范围内流行。21世纪以来,数次冠状病毒感染疫情促使人类更加重视冠状病毒,尤其是COVID-19疫情的暴发与大流行,更将新冠病毒提升为全球的研究重点。免疫反应与病毒的感染、清除以及病理损伤等密切相关。天然免疫是机体防御体系的重要组成部分和首道防线,在病毒感染早期对于抑制病毒的复制和扩散具有至关重要的作用,并且在获得性免疫的启动及后续的发展中也发挥着关键的调控功能。研究表明,免疫逃逸是冠状病毒的重要致病机制,冠状病毒能够通过多种方式抑制宿主的天然免疫应答。现对SARS-CoV-2等主要的冠状病毒抑制天然免疫的分子机制作一概述,以期为抗冠状病毒感染的疫苗及治疗性药物的研发提供帮助。     

SARS-CoV-2 NP和NP-FlaB融合蛋白的免疫原性研究

新型冠状病毒严重急性呼吸综合征冠状病毒2(SARS-CoV-2)感染引发的新型冠状病毒肺炎(COVID-19)疫情在全球持续流行,疫苗的研发和推广使用是阻止新冠疫情的关键手段。SARS-CoV-2核衣壳蛋白(NP)作为病毒的主要结构蛋白,是疫苗开发的潜在候选靶点。鞭毛素B(FlaB)可作为免疫佐剂,增强抗原的免疫原性。本研究对NP和NP-FlaB融合蛋白的免疫原性开展了研究,利用大肠杆菌表达系统分别表达纯化了NP、NP-FlaB融合蛋白,将抗原通过皮下或鼻内途径免疫BALB/c小鼠,分析血清中NP特异性免疫球蛋白G(IgG)、黏膜中NP特异性免疫球蛋白A(IgA)和NP特异性细胞因子分泌的T细胞应答。结果表明:一次皮下免疫NP或NP-FlaB融合蛋白足以引起抗NP的血清IgG抗体反应,能有效诱导分泌白细胞介素4(IL-4)的NP特异性效应T细胞,但NP和NP-FlaB融合蛋白组别之间无显著性差异;鼻内途径免疫下,NP-FlaB融合蛋白免疫组血清中NP特异性IgG抗体滴度和肺内黏膜IgA抗体滴度显著高于NP组。整体结果显示,SARS-CoV-2 NP和NP-FlaB融合蛋白具有很强的免疫原性,NPFlaB融合蛋白能引起黏膜免疫应答,两者均可作为SARS-CoV-2疫苗的候选蛋白。SARS-CoV-2 NP及NP-FlaB融合蛋白的免疫原性的探究为后续新冠病毒NP疫苗开发提供了新的思路和参考。     

血管活性肠肽：潜在的的抗病毒治疗靶点（英文）

病毒感染在临床上十分常见,且部分病毒性疾病有很高的发病率和死亡率,比如正在全球爆发的由严重急性呼吸道综合征冠状病毒-2 (severe acute respiratory syndrome coronavirus-2, SARS-CoV-2)引起的新型冠状病毒肺炎(coronavirus disease2019, COVID-19)。然而,由于反应不足、耐药率增加和严重的不良副作用等原因,目前大多数病毒感染缺乏特定的治疗药物和有效的预防性疫苗。因此,寻找抗病毒感染新的特定治疗靶点非常紧迫,其中“基于多肽的治疗方法”是一个新兴领域。因其高效力和低毒副作用,肽类可能成为很有前景的抗病毒药物。血管活性肠肽(vasoactive intestinal peptide, VIP)是一种具有前瞻性的抗病毒多肽。自1970年成功分离以来,研究证明VIP参与调控SARS-CoV-2、人类免疫缺陷病毒(human immunedeficiencyvirus,HIV)、水泡口炎病毒(vesicularstomatitisvirus, VSV)、呼吸道合胞病毒(respiratorysyncytialvir...     

新型冠状病毒(SARS-CoV-2)的致病过程及疫苗设计策略

2019年12月中国发现了一场由新型冠状病毒(Severe acute respiratory syndromes coronavirus,SARS-CoV-2)感染引发的肺炎疫情,感染者常伴有发热、干咳、呼吸困难等症状,严重情况下会出现急性呼吸窘迫综合征。SARS-CoV-2的致病过程涉及了跨物种传播,侵染宿主细胞以及与免疫系统相互抗争等多个环节,深入了解这一致病过程对于新型治疗药物的研发及病毒疫苗的设计至关重要。因此,本文对SARS-CoV-2的致病过程进行总结,并讨论了针对该病毒的疫苗设计策略。     

编委推荐

正Cell|发现新型冠状病毒抑制宿主防御的新机制近一年来,新型冠状病毒SARS-CoV-2在全球肆虐,引起的新冠肺炎已达3615万例,患者死亡已超过105万例。尽管疫情紧迫,但人们对SARS-CoV-2的致病机制仍知之甚少。美国加州理工大学Guttman及南加州大学Majumdar团队通过综合研究SARS-CoV-2的病毒蛋白与人类RNA之间的相互作用,发现SARS-CoV-2可破坏宿主细胞mRNA的剪接加工、蛋白质翻译及蛋白质运输等过程,从而抑制宿主防御(2020年10月8日在线发表,doi:10.1016/j.cell.2020.10.004)。具体来说,     

新型冠状病毒的相关研究进展

2019年12月出现于湖北武汉的一种新型冠状病毒(SARS-CoV-2)感染所致肺炎疫情,给人类生命安全造成威胁。迄今为止,对2019年出现的SARS-CoV-2的研究仍处于起步阶段,本文就其相关研究进展进行综述,重点阐述了目前关于SARS-CoV-2的病原学与致病机制方面的研究成果,同时对其流行病学以及该病毒引发的肺炎临床特点加以总结,有助于读者及时了解SARS-CoV-2最新的研究动态,并为今后开展治疗药物及疫苗研发提供方向。     

广谱抗冠状病毒疫苗及抗冠状病毒多肽的研究进展

由严重急性呼吸综合征冠状病毒2型(severe acute respiratory syndrome coronavirus 2,SARS-CoV-2)感染引起的2019冠状病毒病(coronavirus disease 2019,COVID-19)暴发,给人类公共卫生安全和全球经济发展造成了严重威胁。疫苗和药物是防治疫情的重要手段,但目前研发的针对冠状病毒的疫苗和药物大多以SARS-CoV-2为靶点,该病毒若发生重大突变或出现新的高致病性冠状病毒,目前研发的有效疫苗或药物可能会无效,而且疫苗和新药的研发往往比较滞后,难以在疫情发生早期投入使用。因此,亟须研发高效、安全、广谱的冠状病毒疫苗和药物,以应对未来可能出现的冠状病毒疫情。本文对广谱冠状病毒疫苗和抗冠状病毒多肽的研究进展进行综述,期望为研发此类疫苗和药物提供参考。     

Discovery of re-purposed drugs that slow SARS-CoV-2 replication in human cells

COVID-19 vaccines based on the Spike protein of SARS-CoV-2 have been developed that appear to be largely successful in stopping infection. However, therapeutics that can help manage the disease are still required until immunity has been achieved globally. The identification of repurposed drugs that stop SARS-CoV-2 replication could have enormous utility in stemming the disease. Here, using a nano-luciferase tagged version of the virus (SARS-CoV-2-ΔOrf7a-NLuc) to quantitate viral load, we evaluated a range of human cell types for their ability to be infected and support replication of the virus, and performed a screen of 1971 FDA-approved drugs. Hepatocytes, kidney glomerulus, and proximal tubule cells were particularly effective in supporting SARS-CoV-2 replication, which is in-line with reported proteinuria and liver damage in patients with COVID-19. Using the nano-luciferase as a measure of virus replication we identified 35 drugs that reduced replication in Vero cells and human hepatocytes when treated prior to SARS-CoV-2 infection and found amodiaquine, atovaquone, bedaquiline, ebastine, LY2835219, manidipine, panobinostat, and vitamin D3 to be effective in slowing SARS-CoV-2 replication in human cells when used to treat infected cells. In conclusion, our study has identified strong candidates for drug repurposing, which could prove powerful additions to the treatment of COVID.     

Host metabolism dysregulation and cell tropism identification in human airway and alveolar organoids upon SARS-CoV-2 infection

The coronavirus disease 2019 (COVID-19) pandemic is caused by infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2),which is spread primary via respiratory droplets and infects the lungs.Currently widely used cell lines and animals are unable to accurately mimic human physiological conditions because of the abnormal status of cell lines (transformed or cancer cells) and species differences between ani-mals and humans.Organoids are stem cell-derived self-organized three-dimensional culture in vitro and model the physiological conditions of natural organs.Here we showed that SARS-CoV-2 infected and extensively replicated in human embryonic stem cells (hESCs)-derived lung organoids,including airway and alveolar organoids which covered the complete infection and spread route for SARS-CoV-2 within lungs.The infected cells were ciliated,club,and alveolar type 2 (AT2) cells,which were sequentially located from the proximal to the distal airway and terminal alveoli,respectively.Addi-tionally,RNA-seq revealed early cell response to virus infection including an unexpected downregulation of the metabolic processes,especially lipid metabolism,in addition to the well-known upregulation of immune response.Further,Remdesivir and a human neutralizing antibody potently inhibited SARS-CoV-2 replication in lung organoids.Therefore,human lung organoids can serve as a pathophysiological model to investigate the underlying mechanism of SARS-CoV-2 infection and to discover and test therapeutic drugs for COVID-19.     

Drugs targeting various stages of the SARS-CoV-2 life cycle: Exploring promising drugs for the treatment of Covid-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a positive-sense, single-stranded RNA virus that causes the potentially lethal Covid-19 respiratory tract infection. It does so by binding to host cell angiotensin converting enzyme 2 (ACE2) receptors, leading to endocytosis with the receptor, and subsequently using the host cell’s machinery to replicate copies of itself and invade new cells. The extent of the spread of infection in the body is dependent on the pattern of ACE2 expression and overreaction of the immune system. Additionally, by inducing an imbalance in the renin-angiotensin-aldosterone system (RAAS) and the loss of ACE2 would favour the progression of inflammatory and thrombotic processes in the lungs. No drug or vaccine has yet been approved to treat human coronaviruses. Hundreds of clinical trials on existing approved drugs from different classes acting on a multitude of targets in the virus life cycle are ongoing to examine potential effectiveness for the prevention and treatment of the infection. This review summarizes the SARS-CoV-2 virus life cycle in the host cell and provides a biological and pathological point of view for repurposed and experimental drugs for this novel coronavirus. The viral life cycle provides potential targets for drug therapy.     

Experimental Models for SARS-CoV-2 Infection

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is a novel virus that causes coronavirus disease 2019 (COVID-19). To understand the identity, functional characteristics and therapeutic targets of the virus and the diseases, appropriate infection models that recapitulate the in vivo pathophysiology of the viral infection are necessary. This article reviews the various infection models, including Vero cells, human cell lines, organoids, and animal models, and discusses their advantages and disadvantages. This knowledge will be helpful for establishing an efficient system for defense against emerging infectious diseases.     

Genotyping coronavirus SARS-CoV-2: methods and implications

The emerging global infectious COVID-19 disease by novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) presents critical threats to global public health and the economy since it was identified in late December 2019 in China. The virus has gone through various pathways of evolution. To understand the evolution and transmission of SARS-CoV-2, genotyping of virus isolates is of great importance. This study presents an accurate method for effectively genotyping SARS-CoV-2 viruses using complete genomes. The method employs the multiple sequence alignments of the genome isolates with the SARS-CoV-2 reference genome. The single-nucleotide polymorphism (SNP) genotypes are then measured by Jaccard distances to track the relationship of virus isolates. The genotyping analysis of SARS-CoV-2 isolates from the globe reveals that specific multiple mutations are the predominated mutation type during the current epidemic. The proposed method serves an effective tool for monitoring and tracking the epidemic of pathogenic viruses in their global and local genetic variations. The genotyping analysis shows that the genes encoding the S proteins and RNA polymerase, RNA primase, and nucleoprotein, undergo frequent mutations. These mutations are critical for vaccine development in disease control.     

新型冠状病毒进化与变异

本文分析了新型冠状病毒(SARS-CoV-2,新冠病毒)的进化来源及刺突蛋白(spike protein, S)基因的突变情况。从GenBank数据库中下载相关病毒全基因组序列及S基因序列,运用DNAMAN 9.0、MEGAX等生物信息学软件,进行多序列比对,构建系统进化树,并统计S基因位点突变情况。分析结果提示,新冠病毒不可能来源于已知的6种人冠状病毒,相较于穿山甲,新冠病毒来源于蝙蝠的可能性更大。S基因的突变率应该和新冠病毒的流行时间及感染人数密切相关。未来,类似于SARS、MERS和新冠病毒这样由动物传播至人的冠状病毒可能还会出现,其流行趋势将取决于其致病性和变异性。     

全球抗病毒药物研发进展与展望

病毒是危害人体健康的主要病原体之一,病毒感染和传播造成的传染性疾病严重威胁人类健康。目前,艾滋病、病毒性肝炎等发病率高、治愈率低的病毒性疾病仍在全球蔓延,流感病毒、冠状病毒等呼吸道病毒不断发生变异,2019年以来,新冠病毒引起的全球疫情对世界各国产生巨大影响,疫情走向还存在很大不确定性,开发安全有效的抗病毒药物成为应对病毒性疾病的重要手段。拟在总结全球抗病毒药物研发整体现状的基础上,分析抗艾滋病病毒、肝炎病毒、新冠病毒等重点领域的新药研发进展,提出抗病毒药物的发展建议,为未来研发更加高效的抗病毒药物提供指引和参考。     

Inter-proteomic posttranslational modifications of the SARS-CoV-2 and the host proteins ‒ A new frontier

Posttranslational modification of proteins, which include both the enzymatic alterations of protein side chains and main-chain peptide bond connectivity, is a fundamental regulatory process that is crucial for almost every aspects of cell biology, including the virus-host cell interaction and the SARS-CoV-2 infection. The posttranslational modification of proteins has primarily been studied in cells and tissues in an intra-proteomic context (where both substrates and enzymes are part of the same species). However, the inter-proteomic posttranslational modifications of most of the SARS-CoV-2 proteins by the host enzymes and vice versa are largely unexplored in virus pathogenesis and in the host immune response. It is now known that the structural spike (S) protein of the SARS-CoV-2 undergoes proteolytic priming by the host serine proteases for entry into the host cells, and N- and O-glycosylation by the host cell enzymes during virion packaging, which enable the virus to spread. New evidence suggests that both SARS-CoV-2 and the host proteins undergo inter-proteomic posttranslational modifications, which play roles in virus pathogenesis and infection-induced immune response by hijacking the host cell signaling. The purpose of this minireview is to bring attention of the scientific community to recent cutting-edge discoveries in this understudied area. It is likely that a better insight into the molecular mechanisms involved may open new research directions, and thereby contribute to novel therapeutic modality development against the SARS-CoV-2. Here we briefly discuss the rationale and touch upon some unanswered questions in this context, especially those that require attention from the scientific community.     

DC/L-SIGN recognition of spike glycoprotein promotes SARS-CoV-2 trans-infection and can be inhibited by a glycomimetic antagonist

The efficient spread of SARS-CoV-2 resulted in a unique pandemic in modern history. Despite early identification of ACE2 as the receptor for viral spike protein, much remains to be understood about the molecular events behind viral dissemination. We evaluated the contribution of C-type lectin receptors (CLR_S) of antigen-presenting cells, widely present in respiratory mucosa and lung tissue. DC-SIGN, L-SIGN, Langerin and MGL bind to diverse glycans of the spike using multiple interaction areas. Using pseudovirus and cells derived from monocytes or T-lymphocytes, we demonstrate that while virus capture by the CLRs examined does not allow direct cell infection, DC/L-SIGN, among these receptors, promote virus transfer to permissive ACE2⁺ Vero E6 cells. A glycomimetic compound designed against DC-SIGN, enable inhibition of this process. These data have been then confirmed using authentic SARS-CoV-2 virus and human respiratory cell lines. Thus, we described a mechanism potentiating viral spreading of infection.     

Mutants of human ACE2 differentially promote SARS-CoV and SARS-CoV-2 spike mediated infection

SARS-CoV and SARS-CoV-2 encode spike proteins that bind human ACE2 on the cell surface to enter target cells during infection. A small fraction of humans encode variants of ACE2, thus altering the biochemical properties at the protein interaction interface. These and other ACE2 coding mutants can reveal how the spike proteins of each virus may differentially engage the ACE2 protein surface during infection. We created an engineered HEK 293T cell line for facile stable transgenic modification, and expressed the major human ACE2 allele or 28 of its missense mutants, 24 of which are possible through single nucleotide changes from the human reference sequence. Infection with SARS-CoV or SARS-CoV-2 spike pseudotyped lentiviruses revealed that high ACE2 cell-surface expression could mask the effects of impaired binding during infection. Drastically reducing ACE2 cell surface expression revealed a range of infection efficiencies across the panel of mutants. Our infection results revealed a non-linear relationship between soluble SARS-CoV-2 RBD binding to ACE2 and pseudovirus infection, supporting a major role for binding avidity during entry. While ACE2 mutants D355N, R357A, and R357T abrogated entry by both SARS-CoV and SARS-CoV-2 spike proteins, the Y41A mutant inhibited SARS-CoV entry much more than SARS-CoV-2, suggesting differential utilization of the ACE2 side-chains within the largely overlapping interaction surfaces utilized by the two CoV spike proteins. These effects correlated well with cytopathic effects observed during SARS-CoV-2 replication in ACE2-mutant cells. The panel of ACE2 mutants also revealed altered ACE2 surface dependencies by the N501Y spike variant, including a near-complete utilization of the K353D ACE2 variant, despite decreased infection mediated by the parental SARS-CoV-2 spike. Our results clarify the relationship between ACE2 abundance, binding, and infection, for various SARS-like coronavirus spike proteins and their mutants, and inform our understanding for how changes to ACE2 sequence may correspond with different susceptibilities to infection.