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.     

An Infectious cDNA Clone of SARS-CoV-2

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新型冠状病毒SARS-CoV-2研究进展

在武汉发生的由新型冠状病毒SARS-CoV-2引发的人类冠状病毒病COVID-19,仅仅2个多月时间在我国及国际上70多个国家出现迅速传播,致病和死亡率高,人类生命受到了极大威胁。一些科学家火速投入研究,对SARS-CoV-2的来源和进化、形态特征和基因结构、感染和致病分子机制开展深入研究,取得了重大进展,为科学防控COVID-19提供了重要依据。根据上述研究的基础,文中对COVID-19病毒疫苗、抗体和抑制剂研发提出了设想,在研究防控COVID-19核心技术上具有一定的参考价值。     

A组轮状病毒可视化RT-LAMP方法的建立

【目的】建立一种利用颜色判定的快速、简单、灵敏度高的检测方法,即可视化的逆转录环介导等温扩增(RT-LAMP)方法,并应用于人A组轮状病毒的基因检测。【方法】针对A组轮状病毒VP6基因的6个保守区域设计4条特异性引物,在64 °C恒温条件下进行核酸扩增反应1 h,在扩增前加入染料钙黄绿素(Calcein)作为反应指示剂,以钙黄绿素的颜色变化作为结果判定标准。评价该方法的特异性和灵敏度,并同时利用RT-LAMP和RT-PCR两种方法对90份临床腹泻样本中的病毒核酸进行检测。【结果】RT-LAMP方法特异性较高,灵敏度可以达到103 copies/μL RNA分子水平,比RT-PCR高出100倍。对临床标本的检出率与RT-PCR方法相当。【结论】建立的RT-LAMP法灵敏度较高,特异性强,节省时间,结果可视化,具有野外检测和现场快速检测的潜力。     

Current advances in the development of SARS-CoV-2 vaccines

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is now a global pandemic that has wreaked havoc globally, which has put a heavy toll on public health, lives, and the world economy. Vaccination is considered as one of the greatest successes in medical history. Based on prior experience with the development of SARS-CoV vaccines, all COVID-19 vaccines must be subjected to the tests for protective effects and harmful risks derived from antibody-dependent enhancement that may contribute to augmented infectivity and/or eosinophilic infiltration. The SARS-CoV-2 vaccine is now being developed urgently in several different ways. China is regarded as one of the world''s leading countries in SARS-CoV-2 vaccine development, up to date the last inactivated vaccine international clinical (Phase III) trial was launched in the United Arab Emirates by Sinopharm China National Biotec Group (CNBG). In this review, we outline the current status of vaccine development against clinically relevant SARS-CoV-2 strains, anticipating that such attempts would help create efficacious and sage SARS-CoV-2 vaccines.     

A trans-complementation system for SARS-CoV-2 recapitulates authentic viral replication without virulence

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Genomic analysis of SARS-CoV-2 reveals local viral evolution in Ghana

The confirmed case fatality rate for the coronavirus disease 2019 (COVID-19) in Ghana has dropped from a peak of 2% in March to be consistently below 1% since May 2020. Globally, case fatality rates have been linked to the strains/clades of circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within a specific country. Here we present 46 whole genomes of SARS-CoV-2 circulating in Ghana, from two separate sequencing batches: 15 isolates from the early epidemic (March 12–April 1 2020) and 31 from later time-points ( 25–27 May 2020). Sequencing was carried out on an Illumina MiSeq system following an amplicon-based enrichment for SARS-CoV-2 cDNA. After genome assembly and quality control processes, phylogenetic analysis showed that the first batch of 15 genomes clustered into five clades: 19A, 19B, 20A, 20B, and 20C, whereas the second batch of 31 genomes clustered to only three clades 19B, 20A, and 20B. The imported cases (6/46) mapped to circulating viruses in their countries of origin, namely, India, Hungary, Norway, the United Kingdom, and the United States of America. All genomes mapped to the original Wuhan strain with high similarity (99.5–99.8%). All imported strains mapped to the European superclade A, whereas 5/9 locally infected individuals harbored the B4 clade, from the East Asian superclade B. Ghana appears to have 19B and 20B as the two largest circulating clades based on our sequence analyses. In line with global reports, the D614G linked viruses seem to be predominating. Comparison of Ghanaian SARS-CoV-2 genomes with global genomes indicates that Ghanaian strains have not diverged significantly from circulating strains commonly imported into Africa. The low level of diversity in our genomes may indicate lower levels of transmission, even for D614G viruses, which is consistent with the relatively low levels of infection reported in Ghana.     

牡蛎单孢子虫环介导等温扩增可视化检测方法的建立

目的:建立基于环介导等温扩增(LAMP)技术的单孢子虫可视化检测方法。方法:根据尼氏单孢子虫的小亚基核糖体RNA保守序列,设计一套特异性LAMP引物,对反应条件如温度和试剂浓度进行优化,建立检测牡蛎单孢子虫的LAMP方法。结果:所建立的方法的敏感性可达1 fg,是常规PCR方法的100倍;全部反应可在1 h内完成;可通过肉眼观察颜色,直接判定结果;对其他牡蛎常见病原体的检测结果均为阴性。结论:建立的LAMP方法简便、快速、灵敏、特异,可用于牡蛎单孢子虫感染的快速检测。     

鸭瘟病毒LAMP可视化检测方法的建立

目的:建立一种快速、简便、特异性高的鸭瘟病毒(DPV)环介导等温扩增(LAMP)检测方法。方法:根据Gen Bank中DPVUI6基因的保守序列设计一套特异性引物,并对反应条件进行优化,建立DPV的LAMP可视化检测方法。结果:建立的LAMP方法对其他鸭常见病原体无扩增反应;可通过肉眼观察颜色直接判定结果;敏感性可达0.1fg,是常规PCR方法的100倍;扩增反应只须在常规水浴锅中进行,可在1 h内完成。结论:建立的DPV LAMP方法简便、快速、灵敏、特异,可用于DPV感染的快速检测。     

新型冠状病毒亚单位疫苗研究进展及现状*

自新型冠状病毒肺炎在2019年年末暴发以来,如何高效防控疫情一直是紧急的全球公共安全事件。疫苗是有效阻止病毒感染人体、保护高危人群免于疾病快速进展以及遏制疫情进一步扩大的手段之一,其中亚单位疫苗的主要成分为特定的病毒抗原蛋白或多肽,通过加入疫苗佐剂提高抗原的免疫原性。由于机体仅针对重组蛋白表面的特定抗原表位进行识别并产生抗体,因此亚单位疫苗具有较高的保护能力和安全性。通过对目前已上市及处于临床阶段的各类新型冠状病毒亚单位疫苗进行梳理,介绍了各类亚单位疫苗的抗原设计策略和佐剂选择、整体保护能力及研究进展,并对亚单位疫苗的应用及技术优势进行分析,期望能为亚单位疫苗研发及全球疫情防控提供参考。     

新冠病毒抗体药物研发进展及展望分析

抗体药物以其独特的作用机制和靶向性强、特异性好等优点,在恶性肿瘤、自身免疫性疾病、感染类疾病的诊断和治疗中发挥着越来越重要的作用,成为国际创新药物研发的热点。新冠肺炎(COVID-19)疫情发生以来,国内外多家研究机构和企业正在加快推进新冠病毒(SARS-CoV-2)抗体药物的开发。在此情势下,认真分析抗体药物现状和趋势,梳理国内外新冠病毒抗体药物研究进展,明确我国当前抗体药物创新的机遇、挑战和建议,对加快我国药物自主创新研发具有重要意义。     

A Daily-Updated Database and Tools for Comprehensive SARS-CoV-2 Mutation-Annotated Trees

The vast scale of SARS-CoV-2 sequencing data has made it increasingly challenging to comprehensively analyze all available data using existing tools and file formats. To address this, we present a database of SARS-CoV-2 phylogenetic trees inferred with unrestricted public sequences, which we update daily to incorporate new sequences. Our database uses the recently proposed mutation-annotated tree (MAT) format to efficiently encode the tree with branches labeled with parsimony-inferred mutations, as well as Nextstrain clade and Pango lineage labels at clade roots. As of June 9, 2021, our SARS-CoV-2 MAT consists of 834,521 sequences and provides a comprehensive view of the virus’ evolutionary history using public data. We also present matUtils—a command-line utility for rapidly querying, interpreting, and manipulating the MATs. Our daily-updated SARS-CoV-2 MAT database and matUtils software are available at http://hgdownload.soe.ucsc.edu/goldenPath/wuhCor1/UShER_SARS-CoV-2/ and https://github.com/yatisht/usher, respectively.     

mRNA Vaccines: Possible Tools to Combat SARS-CoV-2

正Coronaviruses are large, enveloped, positive-strand RNA viruses. Several coronaviruses are pathogenic in humans,including severe acute respiratory syndrome coronavirus(SARS-CoV), Middle East respiratory syndrome coronavirus(MERS-CoV) and this novel virus, SARS-CoV-2,     

Phenotypes and Functions of SARS-CoV-2-Reactive T Cells

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), which is an ongoing pandemic disease. SARS-CoV-2-specific CD4⁺ and CD8⁺ T-cell responses have been detected and characterized not only in COVID-19 patients and convalescents, but also unexposed individuals. Here, we review the phenotypes and functions of SARS-CoV-2-specific T cells in COVID-19 patients and the relationships between SARS-CoV-2-specific T-cell responses and COVID-19 severity. In addition, we describe the phenotypes and functions of SARS-CoV-2-specific memory T cells after recovery from COVID-19 and discuss the presence of SARS-CoV-2-reactive T cells in unexposed individuals and SARS-CoV-2-specific T-cell responses elicited by COVID-19 vaccines. A better understanding of T-cell responses is important for effective control of the current COVID-19 pandemic.     

Assessment of global asymptomatic SARS-CoV-2 infection and management practices from China

With ongoing research, it was found that asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was widespread in coronavirus disease 2019 (COVID-19) populations. Studies have confirmed asymptomatic patients with COVID-19 have potential infectivity, and most of the transmission occurred before symptoms appear. Asymptomatic infection rates varied widely in different countries and regions. Identifying the asymptomatic infected persons and cutting off the infection source is an effective way to prevent the spread of this disease. However, asymptomatic patients have hidden clinical symptoms, and screening based only on the clinical symptoms of COVID-19 can easily lead to a missed diagnosis. Therefore, determining asymptomatic infection patients by SARS-CoV-2 nucleic acid testing is the gold standard. A series of prevention and control measures adopted by the Chinese government, especially the “Four Early” policy, have achieved outstanding achievements, which are worth learning from by other countries.     

用于新型冠状病毒检测的核酸等温扩增技术研究进展

核酸检测作为新型冠状病毒肺炎(COVID-19)筛查诊断和病情监测的主要手段,在疫情防控中发挥了重要作用。虽然实时荧光定量PCR被认为是新型冠状病毒(SARS-CoV-2)核酸检测的金标准,但其依赖荧光定量PCR仪且扩增检测时间较长,难以实现现场快速检测。因此许多基于核酸等温扩增的SARS-CoV-2检测方法相继诞生。等温扩增对仪器温控要求不高,通过与微流控芯片和可视化检测技术结合,可进一步简化操作、降低成本,为SARS-CoV-2现场快速筛查提供有力的技术支撑。本文围绕已报道的SARS-CoV-2等温扩增检测方法原理、检测性能及优缺点进行探讨,为进一步发展SARS-CoV-2现场快速检测平台提供参考。