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1.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-335222

ABSTRACT

Variant of concern (VOC) Omicron-BA1 has achieved global predominance in early 2022. Therefore, surveillance and comprehensive characterization of Omicron-BA.1 in advanced primary cell culture systems and multiple animal models is urgently needed. Here, we characterized Omicron-BA.1 and recombinant Omicron-BA.1 spike gene mutants in comparison with VOC Delta in well-differentiated primary human nasal and bronchial epithelial cells in vitro, followed by in vivo fitness characterization in naïve hamsters, ferrets and hACE2-expressing mice, and in immunized hACE2-mice. We demonstrate a spike-mediated enhancement of early replication of Omicron-BA.1 in nasal epithelial cultures, but limited replication in bronchial epithelial cultures. In Syrian hamsters, Delta showed dominance over Omicron-BA.1 and in ferrets, Omicron-BA.1 infection was abortive. In mice expressing the authentic hACE2-receptor, Delta and a Delta spike clone also showed dominance over Omicron-BA.1 and an Omicron-BA.1 spike clone, respectively. Interestingly, in naïve K18-hACE2 mice, we observed Delta spike-mediated increased replication and pathogenicity and Omicron-BA.1 spike-mediated reduced replication and pathogenicity, suggesting that the spike gene is a major determinant of both Delta and Omicron-BA.1 replication and pathogenicity. Finally, the Omicron-BA.1 spike clone was less well controlled by mRNA-vaccination in K18-hACE2-mice and became more competitive compared to the progenitor and Delta spike clones, suggesting that spike gene-mediated immune evasion is another important factor that led to Omicron-BA.1 dominance.

2.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-293083

ABSTRACT

Rhinoviruses (RV) and inhaled allergens, such as house dust mite (HDM) are the major agents responsible for asthma onset, its life-threatening exacerbations and progression to severe disease. The role of severe acute respiratory syndrome coronavirus (SARS-CoV-2) in exacerbations of asthma or the influence of preexisting viral or allergic airway inflammation on the development of coronavirus disease 2019 (COVID-19) is largely unknown. To address this, we compared molecular mechanisms of HDM, RV and SARS-CoV-2 interactions in experimental RV infection in patients with asthma and healthy individuals. RV infection was sensed via retinoic acid-inducible gene I (RIG-I) helicase, but not via NLR family pyrin domain containing 3 (NLRP3), which led to subsequent apoptosis-associated speck like protein containing a caspase recruitment domain (ASC) recruitment, oligomerization and RIG-I inflammasome activation. This phenomenon was augmented in bronchial epithelium in patients with asthma, especially upon pre-exposure to HDM, which itself induced a priming step, pro-IL-1β release and early inhibition of RIG-I/TANK binding kinase 1/IκB kinase ϵ/type I/III interferons (RIG-I/TBK1/IKKϵ/IFN-I/III) responses. Excessive activation of RIG-I inflammasomes was partially responsible for the alteration and persistence of type I/III IFN responses, prolonged viral clearance and unresolved inflammation in asthma. RV/HDM-induced sustained IFN I/III responses initially restricted SARS-CoV-2 replication in epithelium of patients with asthma, but even this limited infection with SARS-CoV-2 augmented RIG-I inflammasome activation. Timely inhibition of the epithelial RIG-I inflammasome and reduction of IL-1β signaling may lead to more efficient viral clearance and lower the burden of RV and SARS-CoV-2 infection.

3.
Emerg Infect Dis ; 27(7): 1811-1820, 2021 07.
Article in English | MEDLINE | ID: covidwho-1278358

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally, and the number of worldwide cases continues to rise. The zoonotic origins of SARS-CoV-2 and its intermediate and potential spillback host reservoirs, besides humans, remain largely unknown. Because of ethical and experimental constraints and more important, to reduce and refine animal experimentation, we used our repository of well-differentiated airway epithelial cell (AEC) cultures from various domesticated and wildlife animal species to assess their susceptibility to SARS-CoV-2. We observed that SARS-CoV-2 replicated efficiently only in monkey and cat AEC culture models. Whole-genome sequencing of progeny viruses revealed no obvious signs of nucleotide transitions required for SARS-CoV-2 to productively infect monkey and cat AEC cultures. Our findings, together with previous reports of human-to-animal spillover events, warrant close surveillance to determine the potential role of cats, monkeys, and closely related species as spillback reservoirs for SARS-CoV-2.


Subject(s)
Animals, Wild , COVID-19 , Animals , Epithelial Cells , Humans , Respiratory System , SARS-CoV-2
4.
Methods Mol Biol ; 2203: 187-204, 2020.
Article in English | MEDLINE | ID: covidwho-729907

ABSTRACT

Biotin-based proximity labeling circumvents major pitfalls of classical biochemical approaches to identify protein-protein interactions. It consists of enzyme-catalyzed biotin tags ubiquitously apposed on proteins located in close proximity of the labeling enzyme, followed by affinity purification and identification of biotinylated proteins by mass spectrometry. Here we outline the methods by which the molecular microenvironment of the coronavirus replicase/transcriptase complex (RTC), i.e., proteins located within a close perimeter of the RTC, can be determined by different proximity labeling approaches using BirAR118G (BioID), TurboID, and APEX2. These factors represent a molecular signature of coronavirus RTCs and likely contribute to the viral life cycle, thereby constituting attractive targets for the development of antiviral intervention strategies.


Subject(s)
Coronavirus/pathogenicity , Enzymes/genetics , Host-Pathogen Interactions/physiology , Proteomics/methods , Viral Proteins/metabolism , Animals , Ascorbate Peroxidases/genetics , Biotinylation , Carbon-Nitrogen Ligases/genetics , Cell Line , Coronavirus/genetics , Enzymes/metabolism , Escherichia coli Proteins/genetics , Fluorescent Antibody Technique , Microorganisms, Genetically-Modified , Repressor Proteins/genetics , Viral Proteins/chemistry , Viral Proteins/genetics
5.
PLoS Biol ; 19(3): e3001158, 2021 03.
Article in English | MEDLINE | ID: covidwho-1156073

ABSTRACT

Since its emergence in December 2019, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has spread globally and become a major public health burden. Despite its close phylogenetic relationship to SARS-CoV, SARS-CoV-2 exhibits increased human-to-human transmission dynamics, likely due to efficient early replication in the upper respiratory epithelium of infected individuals. Since different temperatures encountered in the human upper and lower respiratory tract (33°C and 37°C, respectively) have been shown to affect the replication kinetics of several respiratory viruses, as well as host innate immune response dynamics, we investigated the impact of temperature on SARS-CoV-2 and SARS-CoV infection using the primary human airway epithelial cell culture model. SARS-CoV-2, in contrast to SARS-CoV, replicated to higher titers when infections were performed at 33°C rather than 37°C. Although both viruses were highly sensitive to type I and type III interferon pretreatment, a detailed time-resolved transcriptome analysis revealed temperature-dependent interferon and pro-inflammatory responses induced by SARS-CoV-2 that were inversely proportional to its replication efficiency at 33°C or 37°C. These data provide crucial insight on pivotal virus-host interaction dynamics and are in line with characteristic clinical features of SARS-CoV-2 and SARS-CoV, as well as their respective transmission efficiencies.


Subject(s)
Gene Expression Profiling/methods , Gene Expression Regulation, Viral/genetics , SARS Virus/genetics , SARS-CoV-2/genetics , Animals , Antiviral Agents/pharmacology , Cells, Cultured , Chlorocebus aethiops , Epithelial Cells/drug effects , Epithelial Cells/metabolism , Epithelial Cells/virology , Gene Expression Regulation, Viral/drug effects , Host-Pathogen Interactions/drug effects , Host-Pathogen Interactions/genetics , Humans , Interferons/pharmacology , SARS Virus/drug effects , SARS Virus/physiology , SARS-CoV-2/drug effects , SARS-CoV-2/physiology , Species Specificity , Temperature , Vero Cells , Virus Replication/drug effects , Virus Replication/genetics
6.
Nature ; 592(7852): 122-127, 2021 04.
Article in English | MEDLINE | ID: covidwho-1104508

ABSTRACT

During the evolution of SARS-CoV-2 in humans, a D614G substitution in the spike glycoprotein (S) has emerged; virus containing this substitution has become the predominant circulating variant in the COVID-19 pandemic1. However, whether the increasing prevalence of this variant reflects a fitness advantage that improves replication and/or transmission in humans or is merely due to founder effects remains unknown. Here we use isogenic SARS-CoV-2 variants to demonstrate that the variant that contains S(D614G) has enhanced binding to the human cell-surface receptor angiotensin-converting enzyme 2 (ACE2), increased replication in primary human bronchial and nasal airway epithelial cultures as well as in a human ACE2 knock-in mouse model, and markedly increased replication and transmissibility in hamster and ferret models of SARS-CoV-2 infection. Our data show that the D614G substitution in S results in subtle increases in binding and replication in vitro, and provides a real competitive advantage in vivo-particularly during the transmission bottleneck. Our data therefore provide an explanation for the global predominance of the variant that contains S(D614G) among the SARS-CoV-2 viruses that are currently circulating.


Subject(s)
COVID-19/transmission , COVID-19/virology , Mutation , SARS-CoV-2/genetics , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/genetics , Virus Replication/genetics , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , Animals , Bronchi/cytology , Bronchi/virology , COVID-19/epidemiology , Cell Line , Cells, Cultured , Cricetinae , Disease Models, Animal , Epithelial Cells/virology , Female , Ferrets/virology , Founder Effect , Gene Knock-In Techniques , Genetic Fitness , Humans , Male , Mesocricetus , Mice , Nasal Mucosa/cytology , Nasal Mucosa/virology , Protein Binding , RNA, Viral/analysis , Receptors, Coronavirus/metabolism , SARS-CoV-2/metabolism , SARS-CoV-2/pathogenicity
7.
bioRxiv ; 2020 Oct 27.
Article in English | MEDLINE | ID: covidwho-915978

ABSTRACT

During the evolution of SARS-CoV-2 in humans a D614G substitution in the spike (S) protein emerged and became the predominant circulating variant (S-614G) of the COVID-19 pandemic 1 . However, whether the increasing prevalence of the S-614G variant represents a fitness advantage that improves replication and/or transmission in humans or is merely due to founder effects remains elusive. Here, we generated isogenic SARS-CoV-2 variants and demonstrate that the S-614G variant has (i) enhanced binding to human ACE2, (ii) increased replication in primary human bronchial and nasal airway epithelial cultures as well as in a novel human ACE2 knock-in mouse model, and (iii) markedly increased replication and transmissibility in hamster and ferret models of SARS-CoV-2 infection. Collectively, our data show that while the S-614G substitution results in subtle increases in binding and replication in vitro , it provides a real competitive advantage in vivo , particularly during the transmission bottle neck, providing an explanation for the global predominance of S-614G variant among the SARS-CoV-2 viruses currently circulating.

8.
Nat Rev Microbiol ; 19(3): 155-170, 2021 03.
Article in English | MEDLINE | ID: covidwho-894400

ABSTRACT

The SARS-CoV-2 pandemic and its unprecedented global societal and economic disruptive impact has marked the third zoonotic introduction of a highly pathogenic coronavirus into the human population. Although the previous coronavirus SARS-CoV and MERS-CoV epidemics raised awareness of the need for clinically available therapeutic or preventive interventions, to date, no treatments with proven efficacy are available. The development of effective intervention strategies relies on the knowledge of molecular and cellular mechanisms of coronavirus infections, which highlights the significance of studying virus-host interactions at the molecular level to identify targets for antiviral intervention and to elucidate critical viral and host determinants that are decisive for the development of severe disease. In this Review, we summarize the first discoveries that shape our current understanding of SARS-CoV-2 infection throughout the intracellular viral life cycle and relate that to our knowledge of coronavirus biology. The elucidation of similarities and differences between SARS-CoV-2 and other coronaviruses will support future preparedness and strategies to combat coronavirus infections.


Subject(s)
COVID-19/virology , SARS-CoV-2/physiology , Animals , COVID-19/drug therapy , Host-Pathogen Interactions , Humans , SARS-CoV-2/chemistry , Viral Proteins/genetics , Viral Proteins/metabolism , Virus Internalization , Virus Replication
9.
Emerg Infect Dis ; 26(7): 1592-1595, 2020 07.
Article in English | MEDLINE | ID: covidwho-712728

ABSTRACT

Infection control instructions call for use of alcohol-based hand rub solutions to inactivate severe acute respiratory syndrome coronavirus 2. We determined the virucidal activity of World Health Organization-recommended hand rub formulations, at full strength and multiple dilutions, and of the active ingredients. All disinfectants demonstrated efficient virus inactivation.


Subject(s)
Alcohols/pharmacology , Betacoronavirus/drug effects , Coronavirus Infections/prevention & control , Disinfectants/pharmacology , Hand Disinfection/methods , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Virus Inactivation , COVID-19 , Humans , SARS-CoV-2 , World Health Organization
11.
Nature ; 582(7813): 561-565, 2020 06.
Article in English | MEDLINE | ID: covidwho-164589

ABSTRACT

Reverse genetics has been an indispensable tool to gain insights into viral pathogenesis and vaccine development. The genomes of large RNA viruses, such as those from coronaviruses, are cumbersome to clone and manipulate in Escherichia coli owing to the size and occasional instability of the genome1-3. Therefore, an alternative rapid and robust reverse-genetics platform for RNA viruses would benefit the research community. Here we show the full functionality of a yeast-based synthetic genomics platform to genetically reconstruct diverse RNA viruses, including members of the Coronaviridae, Flaviviridae and Pneumoviridae families. Viral subgenomic fragments were generated using viral isolates, cloned viral DNA, clinical samples or synthetic DNA, and these fragments were then reassembled in one step in Saccharomyces cerevisiae using transformation-associated recombination cloning to maintain the genome as a yeast artificial chromosome. T7 RNA polymerase was then used to generate infectious RNA to rescue viable virus. Using this platform, we were able to engineer and generate chemically synthesized clones of the virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)4, which has caused the recent pandemic of coronavirus disease (COVID-19), in only a week after receipt of the synthetic DNA fragments. The technical advance that we describe here facilitates rapid responses to emerging viruses as it enables the real-time generation and functional characterization of evolving RNA virus variants during an outbreak.


Subject(s)
Betacoronavirus/genetics , Cloning, Molecular/methods , Coronavirus Infections/virology , Genome, Viral/genetics , Genomics/methods , Pneumonia, Viral/virology , Reverse Genetics/methods , Synthetic Biology/methods , Animals , COVID-19 , China/epidemiology , Chlorocebus aethiops , Chromosomes, Artificial, Yeast/metabolism , Coronavirus Infections/epidemiology , DNA-Directed RNA Polymerases/metabolism , Evolution, Molecular , Humans , Mutation , Pandemics/statistics & numerical data , Pneumonia, Viral/epidemiology , Respiratory Syncytial Viruses/genetics , SARS-CoV-2 , Saccharomyces cerevisiae/genetics , Vero Cells , Viral Proteins/metabolism , Zika Virus/genetics
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