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1.
Viruses ; 13(2)2021 02 03.
Article in English | MEDLINE | ID: covidwho-1060766

ABSTRACT

The long-term control strategy of SARS-CoV-2 and other major respiratory viruses needs to include antivirals to treat acute infections, in addition to the judicious use of effective vaccines. Whilst COVID-19 vaccines are being rolled out for mass vaccination, the modest number of antivirals in use or development for any disease bears testament to the challenges of antiviral development. We recently showed that non-cytotoxic levels of thapsigargin (TG), an inhibitor of the sarcoplasmic/endoplasmic reticulum (ER) Ca2+ ATPase pump, induces a potent host innate immune antiviral response that blocks influenza A virus replication. Here we show that TG is also highly effective in blocking the replication of respiratory syncytial virus (RSV), common cold coronavirus OC43, SARS-CoV-2 and influenza A virus in immortalized or primary human cells. TG's antiviral performance was significantly better than remdesivir and ribavirin in their respective inhibition of OC43 and RSV. Notably, TG was just as inhibitory to coronaviruses (OC43 and SARS-CoV-2) and influenza viruses (USSR H1N1 and pdm 2009 H1N1) in separate infections as in co-infections. Post-infection oral gavage of acid-stable TG protected mice against a lethal influenza virus challenge. Together with its ability to inhibit the different viruses before or during active infection, and with an antiviral duration of at least 48 h post-TG exposure, we propose that TG (or its derivatives) is a promising broad-spectrum inhibitor against SARS-CoV-2, OC43, RSV and influenza virus.


Subject(s)
Antiviral Agents/pharmacology , Betacoronavirus/drug effects , Coronavirus OC43, Human/drug effects , Influenza A Virus, H1N1 Subtype/drug effects , Respiratory Syncytial Virus, Human/drug effects , Thapsigargin/pharmacology , Animals , Antiviral Agents/therapeutic use , Betacoronavirus/physiology , Cell Line , Cell Line, Tumor , Cells, Cultured , Coronavirus OC43, Human/physiology , Endoplasmic Reticulum Stress , Humans , Influenza A Virus, H1N1 Subtype/physiology , Mice , Microbial Sensitivity Tests , Orthomyxoviridae Infections/drug therapy , Orthomyxoviridae Infections/virology , Respiratory Syncytial Virus, Human/physiology , Ribavirin/pharmacology , Thapsigargin/therapeutic use , Virus Replication/drug effects
2.
Cells ; 10(2)2021 02 02.
Article in English | MEDLINE | ID: covidwho-1060037

ABSTRACT

Many viruses disrupt host gene expression by degrading host mRNAs and/or manipulating translation activities to create a cellular environment favorable for viral replication. Often, virus-induced suppression of host gene expression, including those involved in antiviral responses, contributes to viral pathogenicity. Accordingly, clarifying the mechanisms of virus-induced disruption of host gene expression is important for understanding virus-host cell interactions and virus pathogenesis. Three highly pathogenic human coronaviruses (CoVs), including severe acute respiratory syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)-CoV, and SARS-CoV-2, have emerged in the past two decades. All of them encode nonstructural protein 1 (nsp1) in their genomes. Nsp1 of SARS-CoV and MERS-CoV exhibit common biological functions for inducing endonucleolytic cleavage of host mRNAs and inhibition of host translation, while viral mRNAs evade the nsp1-induced mRNA cleavage. SARS-CoV nsp1 is a major pathogenic determinant for this virus, supporting the notion that a viral protein that suppresses host gene expression can be a virulence factor, and further suggesting the possibility that SARS-CoV-2 nsp1, which has high amino acid identity with SARS-CoV nsp1, may serve as a major virulence factor. This review summarizes the gene expression suppression functions of nsp1 of CoVs, with a primary focus on SARS-CoV nsp1 and MERS-CoV nsp1.


Subject(s)
Betacoronavirus , Coronavirus Infections/virology , Viral Nonstructural Proteins/physiology , Animals , Betacoronavirus/pathogenicity , Betacoronavirus/physiology , Gene Expression Regulation , Host Microbial Interactions , Humans , Mice , RNA, Messenger/genetics , Virus Replication
3.
Int J Mol Sci ; 22(3)2021 Jan 28.
Article in English | MEDLINE | ID: covidwho-1055069

ABSTRACT

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is a novel epidemic strain of Betacoronavirus that is responsible for the current viral pandemic, coronavirus disease 2019 (COVID-19), a global health crisis. Other epidemic Betacoronaviruses include the 2003 SARS-CoV-1 and the 2009 Middle East Respiratory Syndrome Coronavirus (MERS-CoV), the genomes of which, particularly that of SARS-CoV-1, are similar to that of the 2019 SARS-CoV-2. In this extensive review, we document the most recent information on Coronavirus proteins, with emphasis on the membrane proteins in the Coronaviridae family. We include information on their structures, functions, and participation in pathogenesis. While the shared proteins among the different coronaviruses may vary in structure and function, they all seem to be multifunctional, a common theme interconnecting these viruses. Many transmembrane proteins encoded within the SARS-CoV-2 genome play important roles in the infection cycle while others have functions yet to be understood. We compare the various structural and nonstructural proteins within the Coronaviridae family to elucidate potential overlaps and parallels in function, focusing primarily on the transmembrane proteins and their influences on host membrane arrangements, secretory pathways, cellular growth inhibition, cell death and immune responses during the viral replication cycle. We also offer bioinformatic analyses of potential viroporin activities of the membrane proteins and their sequence similarities to the Envelope (E) protein. In the last major part of the review, we discuss complement, stimulation of inflammation, and immune evasion/suppression that leads to CoV-derived severe disease and mortality. The overall pathogenesis and disease progression of CoVs is put into perspective by indicating several stages in the resulting infection process in which both host and antiviral therapies could be targeted to block the viral cycle. Lastly, we discuss the development of adaptive immunity against various structural proteins, indicating specific vulnerable regions in the proteins. We discuss current CoV vaccine development approaches with purified proteins, attenuated viruses and DNA vaccines.


Subject(s)
Betacoronavirus/physiology , Coronavirus Infections/metabolism , Viral Matrix Proteins/metabolism , Animals , Betacoronavirus/genetics , Betacoronavirus/immunology , /metabolism , Coronavirus Infections/immunology , Coronavirus Infections/pathology , Genome, Viral , Host-Pathogen Interactions , Humans , Immune Evasion , Protein Interaction Maps , /immunology , Viral Matrix Proteins/genetics , Viral Matrix Proteins/immunology , Virus Internalization , Virus Replication
6.
Life Sci ; 253: 117723, 2020 Jul 15.
Article in English | MEDLINE | ID: covidwho-1023706

ABSTRACT

Coronavirus Disease 2019 (COVID-19) has quickly progressed to a global health emergency. Respiratory illness is the major cause of morbidity and mortality in these patients with the disease spectrum ranging from asymptomatic subclinical infection, to severe pneumonia progressing to acute respiratory distress syndrome. There is growing evidence describing pathophysiological resemblance of SARS-CoV-2 infection with other coronavirus infections such as Severe Acute Respiratory Syndrome coronavirus and Middle East Respiratory Syndrome coronavirus (MERS-CoV). Angiotensin Converting Enzyme-2 receptors play a pivotal role in the pathogenesis of the virus. Disruption of this receptor leads to cardiomyopathy, cardiac dysfunction, and heart failure. Patients with cardiovascular disease are more likely to be infected with SARS-CoV-2 and they are more likely to develop severe symptoms. Hypertension, arrhythmia, cardiomyopathy and coronary heart disease are amongst major cardiovascular disease comorbidities seen in severe cases of COVID-19. There is growing literature exploring cardiac involvement in SARS-CoV-2. Myocardial injury is one of the important pathogenic features of COVID-19. As a surrogate for myocardial injury, multiple studies have shown increased cardiac biomarkers mainly cardiac troponins I and T in the infected patients especially those with severe disease. Myocarditis is depicted as another cause of morbidity amongst COVID-19 patients. The exact mechanisms of how SARS-CoV-2 can cause myocardial injury are not clearly understood. The proposed mechanisms of myocardial injury are direct damage to the cardiomyocytes, systemic inflammation, myocardial interstitial fibrosis, interferon mediated immune response, exaggerated cytokine response by Type 1 and 2 helper T cells, in addition to coronary plaque destabilization, and hypoxia.


Subject(s)
Betacoronavirus/physiology , Coronavirus Infections/pathology , Myocardium/pathology , Pneumonia, Viral/pathology , Coronavirus Infections/immunology , Humans , Myocarditis/virology , Myocytes, Cardiac/pathology , Myocytes, Cardiac/virology , Pandemics , Pneumonia, Viral/immunology
7.
Appl Environ Microbiol ; 86(23)2020 11 10.
Article in English | MEDLINE | ID: covidwho-1020865

ABSTRACT

Emerging outbreaks of airborne pathogenic infections worldwide, such as the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, have raised the need to understand parameters affecting the airborne survival of microbes in order to develop measures for effective infection control. We report a novel experimental strategy, TAMBAS (tandem approach for microphysical and biological assessment of airborne microorganism survival), to explore the synergistic interactions between the physicochemical and biological processes that impact airborne microbe survival in aerosol droplets. This innovative approach provides a unique and detailed understanding of the processes taking place from aerosol droplet generation through to equilibration and viability decay in the local environment, elucidating decay mechanisms not previously described. The impact of evaporation kinetics, solute hygroscopicity and concentration, particle morphology, and equilibrium particle size on airborne survival are reported, using Escherichia coli MRE162 as a benchmark system. For this system, we report that (i) particle crystallization does not directly impact microbe longevity, (ii) bacteria act as crystallization nuclei during droplet drying and equilibration, and (iii) the kinetics of size and compositional change appear to have a larger effect on microbe longevity than the equilibrium solute concentration.IMPORTANCE A transformative approach to identify the physicochemical processes that impact the biological decay rates of bacteria in aerosol droplets is described. It is shown that the evaporation process and changes in the phase and morphology of the aerosol particle during evaporation impact microorganism viability. The equilibrium droplet size was found to affect airborne bacterial viability. Furthermore, the presence of Escherichia coli MRE162 in a droplet does not affect aerosol growth/evaporation but influences the dynamic behavior of the aerosol by processing the culture medium prior to aerosolization, affecting the hygroscopicity of the culture medium; this highlights the importance of the inorganic and organic chemical composition within the aerosolized droplets that impact hygroscopicity. Bacteria also act as crystallization nuclei. The novel approach and data have implications for increased mechanistic understanding of aerosol survival and infectivity in bioaerosol studies spanning the medical, veterinary, farming, and agricultural fields, including the role of microorganisms in atmospheric processing and cloud formation.


Subject(s)
Aerosols , Air Microbiology , Coronavirus Infections/transmission , Escherichia coli Infections/transmission , Infection Control/methods , Pneumonia, Viral/transmission , Betacoronavirus/physiology , Cough/microbiology , Crystallization , Escherichia coli/physiology , Humans , Microbial Viability , Pandemics , Particle Size , Sneezing/physiology
9.
J Infect Dis ; 222(5): 722-725, 2020 Aug 04.
Article in English | MEDLINE | ID: covidwho-990710

ABSTRACT

The ongoing coronavirus disease 2019 pandemic has forced the clinical and scientific community to try drug repurposing of existing antiviral agents as a quick option against severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2). Under this scenario, interferon (IFN) ß-1a, whose antiviral potential is already known, and which is a drug currently used in the clinical management of multiple sclerosis, may represent as a potential candidate. In this report, we demonstrate that IFN-ß-1a was highly effective in inhibiting in vitro SARS-CoV-2 replication at clinically achievable concentration when administered after virus infection.


Subject(s)
Antiviral Agents/pharmacology , Betacoronavirus/drug effects , Coronavirus Infections/drug therapy , Coronavirus Infections/virology , Interferon beta-1a/pharmacology , Pneumonia, Viral/drug therapy , Pneumonia, Viral/virology , Animals , Betacoronavirus/physiology , Chlorocebus aethiops , Drug Repositioning , Pandemics , Vero Cells , Virus Replication/drug effects
10.
Arch Immunol Ther Exp (Warsz) ; 68(6): 35, 2020 Nov 13.
Article in English | MEDLINE | ID: covidwho-983490

ABSTRACT

The COVID-19 pandemic developing rapidly in 2020 is triggered by the emergence of a new human virus-SARS-CoV-2. The emergence of a new virus is not an unexpected phenomenon and has been predicted for many years. Since the virus has spread all over the world, it will be very difficult or even impossible to eradicate it. A necessary condition for complete or partial elimination of the virus is to have an effective vaccine. It is possible that SARS-CoV-2 will become milder in the next few years and COVID-19 will then only threaten individuals from risk groups.


Subject(s)
Betacoronavirus/physiology , Coronavirus Infections/epidemiology , Pandemics , Pneumonia, Viral/epidemiology , Animals , Betacoronavirus/pathogenicity , Biological Evolution , Communicable Disease Control/organization & administration , Communicable Diseases, Emerging , Coronaviridae/genetics , Coronaviridae/pathogenicity , Coronavirus Infections/transmission , Coronavirus Infections/veterinary , Coronavirus Infections/virology , Disease Eradication , Disease Susceptibility , Forecasting , Host Specificity , Humans , Pandemics/prevention & control , Pneumonia, Viral/transmission , Pneumonia, Viral/virology , Selection, Genetic , Virulence , Zoonoses
11.
Molecules ; 25(21)2020 Oct 22.
Article in English | MEDLINE | ID: covidwho-983191

ABSTRACT

Inflammation is a biological response to the activation of the immune system by various infectious or non-infectious agents, which may lead to tissue damage and various diseases. Gut commensal bacteria maintain a symbiotic relationship with the host and display a critical function in the homeostasis of the host immune system. Disturbance to the gut microbiota leads to immune dysfunction both locally and at distant sites, which causes inflammatory conditions not only in the intestine but also in the other organs such as lungs and brain, and may induce a disease state. Probiotics are well known to reinforce immunity and counteract inflammation by restoring symbiosis within the gut microbiota. As a result, probiotics protect against various diseases, including respiratory infections and neuroinflammatory disorders. A growing body of research supports the beneficial role of probiotics in lung and mental health through modulating the gut-lung and gut-brain axes. In the current paper, we discuss the potential role of probiotics in the treatment of viral respiratory infections, including the COVID-19 disease, as major public health crisis in 2020, and influenza virus infection, as well as treatment of neurological disorders like multiple sclerosis and other mental illnesses.


Subject(s)
Coronavirus Infections/therapy , Influenza, Human/therapy , Mental Disorders/therapy , Multiple Sclerosis/therapy , Pneumonia, Viral/therapy , Probiotics/therapeutic use , Respiratory Tract Infections/therapy , Betacoronavirus/drug effects , Betacoronavirus/pathogenicity , Betacoronavirus/physiology , Brain/immunology , Coronavirus Infections/immunology , Coronavirus Infections/microbiology , Coronavirus Infections/virology , Gastrointestinal Microbiome/immunology , Gastrointestinal Tract/immunology , Gastrointestinal Tract/microbiology , Humans , Immunomodulation , Influenza, Human/immunology , Influenza, Human/microbiology , Influenza, Human/virology , Lung/immunology , Mental Disorders/immunology , Mental Disorders/microbiology , Microbial Consortia/immunology , Multiple Sclerosis/immunology , Multiple Sclerosis/microbiology , Orthomyxoviridae/drug effects , Orthomyxoviridae/pathogenicity , Orthomyxoviridae/physiology , Pandemics , Pneumonia, Viral/immunology , Pneumonia, Viral/microbiology , Pneumonia, Viral/virology , Respiratory Tract Infections/immunology , Respiratory Tract Infections/microbiology , Symbiosis/immunology
12.
Molecules ; 25(21)2020 Oct 22.
Article in English | MEDLINE | ID: covidwho-983187

ABSTRACT

Viral infections and associated diseases are responsible for a substantial number of mortality and public health problems around the world. Each year, infectious diseases kill 3.5 million people worldwide. The current pandemic caused by COVID-19 has become the greatest health hazard to people in their lifetime. There are many antiviral drugs and vaccines available against viruses, but they have many disadvantages, too. There are numerous side effects for conventional drugs, and active mutation also creates drug resistance against various viruses. This has led scientists to search herbs as a source for the discovery of more efficient new antivirals. According to the World Health Organization (WHO), 65% of the world population is in the practice of using plants and herbs as part of treatment modality. Additionally, plants have an advantage in drug discovery based on their long-term use by humans, and a reduced toxicity and abundance of bioactive compounds can be expected as a result. In this review, we have highlighted the important viruses, their drug targets, and their replication cycle. We provide in-depth and insightful information about the most favorable plant extracts and their derived phytochemicals against viral targets. Our major conclusion is that plant extracts and their isolated pure compounds are essential sources for the current viral infections and useful for future challenges.


Subject(s)
Antiviral Agents/therapeutic use , Coronavirus Infections/drug therapy , HIV Infections/drug therapy , Hepatitis C, Chronic/drug therapy , Herpes Simplex/drug therapy , Influenza, Human/drug therapy , Phytochemicals/therapeutic use , Pneumonia, Viral/drug therapy , Antiviral Agents/chemistry , Antiviral Agents/classification , Antiviral Agents/isolation & purification , Betacoronavirus/drug effects , Betacoronavirus/pathogenicity , Betacoronavirus/physiology , Coronavirus Infections/pathology , Coronavirus Infections/virology , Drug Discovery , HIV/drug effects , HIV/pathogenicity , HIV/physiology , HIV Infections/pathology , HIV Infections/virology , Hepacivirus/drug effects , Hepacivirus/pathogenicity , Hepacivirus/physiology , Hepatitis C, Chronic/pathology , Hepatitis C, Chronic/virology , Herpes Simplex/pathology , Herpes Simplex/virology , Humans , Influenza, Human/pathology , Influenza, Human/virology , Orthomyxoviridae/drug effects , Orthomyxoviridae/pathogenicity , Orthomyxoviridae/physiology , Pandemics , Phytochemicals/chemistry , Phytochemicals/classification , Phytochemicals/isolation & purification , Plants, Medicinal , Pneumonia, Viral/pathology , Pneumonia, Viral/virology , Simplexvirus/drug effects , Simplexvirus/pathogenicity , Simplexvirus/physiology , Virus Internalization/drug effects , Virus Replication/drug effects
13.
Zool Res ; 41(6): 621-631, 2020 11 18.
Article in English | MEDLINE | ID: covidwho-982982

ABSTRACT

Understanding the pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and clarifying antiviral immunity in hosts are critical aspects for the development of vaccines and antivirals. Mice are frequently used to generate animal models of infectious diseases due to their convenience and ability to undergo genetic manipulation. However, normal adult mice are not susceptible to SARS-CoV-2. Here, we developed a viral receptor (human angiotensin-converting enzyme 2, hACE2) pulmonary transfection mouse model to establish SARS-CoV-2 infection rapidly in the mouse lung. Based on the model, the virus successfully infected the mouse lung 2 days after transfection. Viral RNA/protein, innate immune cell infiltration, inflammatory cytokine expression, and pathological changes in the infected lungs were observed after infection. Further studies indicated that neutrophils were the first and most abundant leukocytes to infiltrate the infected lungs after viral infection. In addition, using infected CXCL5-knockout mice, chemokine CXCL5 was responsible for neutrophil recruitment. CXCL5 knockout decreased lung inflammation without diminishing viral clearance, suggesting a potential target for controlling pneumonia.


Subject(s)
Betacoronavirus/immunology , Chemokine CXCL5/immunology , Coronavirus Infections/immunology , Immunity, Innate/immunology , Neutrophils/immunology , Peptidyl-Dipeptidase A/immunology , Pneumonia, Viral/immunology , Animals , Betacoronavirus/genetics , Betacoronavirus/physiology , Cell Line , Chemokine CXCL5/genetics , Chemokine CXCL5/metabolism , Coronavirus Infections/genetics , Coronavirus Infections/virology , Cytokines/immunology , Cytokines/metabolism , Disease Models, Animal , Humans , Male , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic , Neutrophils/metabolism , Neutrophils/virology , Pandemics , Peptidyl-Dipeptidase A/genetics , Peptidyl-Dipeptidase A/metabolism , Pneumonia, Viral/genetics , Pneumonia, Viral/virology
14.
Zool Res ; 41(6): 705-708, 2020 Nov 18.
Article in English | MEDLINE | ID: covidwho-982981

ABSTRACT

Since the first reported severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in December 2019, coronavirus disease 2019 (COVID-19) has become a global pandemic, spreading to more than 200 countries and regions worldwide. With continued research progress and virus detection, SARS-CoV-2 genomes and sequencing data have been reported and accumulated at an unprecedented rate. To meet the need for fast analysis of these genome sequences, the National Genomics Data Center (NGDC) of the China National Center for Bioinformation (CNCB) has established an online coronavirus analysis platform, which includes de novoassembly, BLAST alignment, genome annotation, variant identification, and variant annotation modules. The online analysis platform can be freely accessed at the 2019 Novel Coronavirus Resource (2019nCoVR) (https://bigd.big.ac.cn/ncov/online/tools).


Subject(s)
Betacoronavirus/genetics , Computational Biology/methods , Coronavirus Infections/diagnosis , Genome, Viral/genetics , Genomics/methods , High-Throughput Nucleotide Sequencing/methods , Pneumonia, Viral/diagnosis , Animals , Betacoronavirus/classification , Betacoronavirus/physiology , China , Computational Biology/organization & administration , Coronavirus Infections/virology , Genetic Variation , Humans , Internet , Molecular Sequence Annotation , Pandemics , Pneumonia, Viral/virology
15.
Viruses ; 12(10)2020 09 26.
Article in English | MEDLINE | ID: covidwho-982816

ABSTRACT

In a short time, the COVID-19 pandemic has left the world with over 25 million cases and staggering death tolls that are still rising. Treatments for SARS-CoV-2 infection are desperately needed as there are currently no approved drug therapies. With limited knowledge of viral mechanisms, a network controllability method of prioritizing existing drugs for repurposing efforts is optimal for quickly moving through the drug approval pipeline using limited, available, virus-specific data. Based on network topology and controllability, 16 proteins involved in translation, cellular transport, cellular stress, and host immune response are predicted as regulators of the SARS-CoV-2 infected cell. Of the 16, eight are prioritized as possible drug targets where two, PVR and SCARB1, are previously unexplored. Known compounds targeting these genes are suggested for viral inhibition study. Prioritized proteins in agreement with previous analysis and viral inhibition studies verify the ability of network controllability to predict biologically relevant candidates.


Subject(s)
Betacoronavirus/drug effects , Coronavirus Infections/drug therapy , Drug Repositioning/methods , Pneumonia, Viral/drug therapy , Betacoronavirus/isolation & purification , Betacoronavirus/physiology , Coronavirus Infections/metabolism , Coronavirus Infections/virology , Drug Approval , Drug Delivery Systems , Host-Pathogen Interactions , Humans , Pandemics , Pneumonia, Viral/metabolism , Pneumonia, Viral/virology , Protein Interaction Maps/drug effects , Receptors, Virus/genetics , Receptors, Virus/metabolism , Scavenger Receptors, Class B/metabolism , Virus Integration
16.
J Virol ; 94(22)2020 10 27.
Article in English | MEDLINE | ID: covidwho-982503

ABSTRACT

Animal models recapitulating human COVID-19 disease, especially severe disease, are urgently needed to understand pathogenesis and to evaluate candidate vaccines and therapeutics. Here, we develop novel severe-disease animal models for COVID-19 involving disruption of adaptive immunity in Syrian hamsters. Cyclophosphamide (CyP) immunosuppressed or RAG2 knockout (KO) hamsters were exposed to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by the respiratory route. Both the CyP-treated and RAG2 KO hamsters developed clinical signs of disease that were more severe than those in immunocompetent hamsters, notably weight loss, viral loads, and fatality (RAG2 KO only). Disease was prolonged in transiently immunosuppressed hamsters and was uniformly lethal in RAG2 KO hamsters. We evaluated the protective efficacy of a neutralizing monoclonal antibody and found that pretreatment, even in immunosuppressed animals, limited infection. Our results suggest that functional B and/or T cells are not only important for the clearance of SARS-CoV-2 but also play an early role in protection from acute disease.IMPORTANCE Syrian hamsters are in use as a model of disease caused by SARS-CoV-2. Pathology is pronounced in the upper and lower respiratory tract, and disease signs and endpoints include weight loss and viral RNA and/or infectious virus in swabs and organs (e.g., lungs). However, a high dose of virus is needed to produce disease, and the disease resolves rapidly. Here, we demonstrate that immunosuppressed hamsters are susceptible to low doses of virus and develop more severe and prolonged disease. We demonstrate the efficacy of a novel neutralizing monoclonal antibody using the cyclophosphamide transient suppression model. Furthermore, we demonstrate that RAG2 knockout hamsters develop severe/fatal disease when exposed to SARS-CoV-2. These immunosuppressed hamster models provide researchers with new tools for evaluating therapies and vaccines and understanding COVID-19 pathogenesis.


Subject(s)
Coronavirus Infections/immunology , Coronavirus Infections/pathology , Disease Models, Animal , Mesocricetus , Pneumonia, Viral/immunology , Pneumonia, Viral/pathology , Adaptive Immunity , Animals , Animals, Genetically Modified , Betacoronavirus/physiology , Cyclophosphamide , DNA-Binding Proteins/genetics , Gene Knockout Techniques , Immunosuppressive Agents , Pandemics , Severity of Illness Index
17.
J Virol ; 94(23)2020 11 09.
Article in English | MEDLINE | ID: covidwho-975641

ABSTRACT

Coronaviruses (CoVs) stand out for their large RNA genome and complex RNA-synthesizing machinery comprising 16 nonstructural proteins (nsps). The bifunctional nsp14 contains 3'-to-5' exoribonuclease (ExoN) and guanine-N7-methyltransferase (N7-MTase) domains. While the latter presumably supports mRNA capping, ExoN is thought to mediate proofreading during genome replication. In line with such a role, ExoN knockout mutants of mouse hepatitis virus (MHV) and severe acute respiratory syndrome coronavirus (SARS-CoV) were previously reported to have crippled but viable hypermutation phenotypes. Remarkably, using reverse genetics, a large set of corresponding ExoN knockout mutations has now been found to be lethal for another betacoronavirus, Middle East respiratory syndrome coronavirus (MERS-CoV). For 13 mutants, viral progeny could not be recovered, unless-as happened occasionally-reversion had first occurred. Only a single mutant was viable, likely because its E191D substitution is highly conservative. Remarkably, a SARS-CoV-2 ExoN knockout mutant was found to be unable to replicate, resembling observations previously made for alpha- and gammacoronaviruses, but starkly contrasting with the documented phenotype of ExoN knockout mutants of the closely related SARS-CoV. Subsequently, we established in vitro assays with purified recombinant MERS-CoV nsp14 to monitor its ExoN and N7-MTase activities. All ExoN knockout mutations that proved lethal in reverse genetics were found to severely decrease ExoN activity while not affecting N7-MTase activity. Our study strongly suggests that CoV nsp14 ExoN has an additional function, which apparently is critical for primary viral RNA synthesis and thus differs from the proofreading function that, based on previous MHV and SARS-CoV studies, was proposed to boost longer-term replication fidelity.IMPORTANCE The bifunctional nsp14 subunit of the coronavirus replicase contains 3'-to-5' exoribonuclease (ExoN) and guanine-N7-methyltransferase domains. For the betacoronaviruses MHV and SARS-CoV, ExoN was reported to promote the fidelity of genome replication, presumably by mediating a form of proofreading. For these viruses, ExoN knockout mutants are viable while displaying an increased mutation frequency. Strikingly, we have now established that the equivalent ExoN knockout mutants of two other betacoronaviruses, MERS-CoV and SARS-CoV-2, are nonviable, suggesting an additional and critical ExoN function in their replication. This is remarkable in light of the very limited genetic distance between SARS-CoV and SARS-CoV-2, which is highlighted, for example, by 95% amino acid sequence identity in their nsp14 sequences. For (recombinant) MERS-CoV nsp14, both its enzymatic activities were evaluated using newly developed in vitro assays that can be used to characterize these key replicative enzymes in more detail and explore their potential as target for antiviral drug development.


Subject(s)
Betacoronavirus/physiology , Exoribonucleases/metabolism , Middle East Respiratory Syndrome Coronavirus/physiology , Viral Nonstructural Proteins/metabolism , Virus Replication , Animals , Betacoronavirus/enzymology , Betacoronavirus/genetics , Catalytic Domain , Cell Line , Exoribonucleases/chemistry , Exoribonucleases/genetics , Fluorouracil/pharmacology , Gene Knockout Techniques , Genome, Viral , Humans , Methylation , Middle East Respiratory Syndrome Coronavirus/enzymology , Middle East Respiratory Syndrome Coronavirus/genetics , Mutation , RNA, Viral/biosynthesis , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Viral Nonstructural Proteins/chemistry , Viral Nonstructural Proteins/genetics , Viral Plaque Assay , Zinc Fingers
18.
Mol Pharmacol ; 98(5): 612-619, 2020 11.
Article in English | MEDLINE | ID: covidwho-975622

ABSTRACT

Heparan sulfate proteoglycans (HSPGs) are cell surface receptors that are involved in the cellular uptake of pathologic amyloid proteins and viruses, including the novel coronavirus; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Heparin and heparan sulfate antagonize the binding of these pathogens to HSPGs and stop their cellular internalization, but the anticoagulant effect of these agents has been limiting their use in the treatment of viral infections. Heparin-binding peptides (HBPs) are suitable nonanticoagulant agents that are capable of antagonizing binding of heparin-binding pathogens to HSPGs. Here, we review and discuss the use of HBPs as viral uptake inhibitors and will address their benefits and limitations to treat viral infections. Furthermore, we will discuss a variant of these peptides that is in the clinic and can be considered as a novel therapy in coronavirus disease 2019 (COVID-19) infection. SIGNIFICANCE STATEMENT: The need to discover treatment modalities for COVID-19 is a necessity, and therapeutic interventions such as heparin-binding peptides (HBPs), which are used for other cases, can be beneficial based on their mechanisms of actions. In this paper, we have discussed the application of HBPs as viral uptake inhibitors in COVID-19 and explained possible mechanisms of actions and the therapeutic effects.


Subject(s)
Antiviral Agents/metabolism , Betacoronavirus/physiology , Coronavirus Infections/drug therapy , Heparan Sulfate Proteoglycans/metabolism , Peptides/metabolism , Pneumonia, Viral/drug therapy , Spike Glycoprotein, Coronavirus/metabolism , Virus Internalization/drug effects , Animals , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Antiviral Agents/therapeutic use , Heparan Sulfate Proteoglycans/chemistry , Humans , Pandemics , Peptides/chemistry , Peptides/pharmacology , Peptides/therapeutic use , Spike Glycoprotein, Coronavirus/chemistry
20.
Pan Afr Med J ; 35(Suppl 2): 147, 2020.
Article in English | MEDLINE | ID: covidwho-946297

ABSTRACT

Coronavirus disease (COVID-19) caused by SARS-CoV-2-a new single-stranded RNA virus with respiratory system proclivity and epithelial cell- is a novel infectious disease that originated in Wuhan, China in December, 2019 and has spread to many countries with the total number of confirmed cases put at 20,259,579 cases as of 12th August, 2020. It is transmitted from human-to-human via droplets. When an infected person coughs or sneezes, these droplets find their way into the mouth or nostrils of another person that is within a close range. Alternatively it can be contracted by touching infected hard surfaces and using the same hands to touch the mouth, nose and eye(s). COVID-19 has been declared a global pandemic by the World Health Organization (WHO) on 11th March, 2020. There is currently no therapeutic substance accepted as a panacea for the prophylaxis of this infectious disease. As a result of this back drop, many nations have instituted fourteen (14) days quarantine for suspected cases, social distancing and border closure in an attempt to curb the spread of COVID-19. There has been several conspirary theories that emanated since the disease was declared a pandemic. This paper provides useful information to serve as reference to those who seek proper understanding of COVID-19 and its deleterious effects in the body, by distiguishing between the factsand the conspiracy theoriesof coronavirus disease.


Subject(s)
Attitude to Health , Betacoronavirus/pathogenicity , Coronavirus Infections/epidemiology , Delusions , Pandemics , Pneumonia, Viral/epidemiology , Aerosols , Air Microbiology , Betacoronavirus/physiology , Bioterrorism , Communicable Disease Control/organization & administration , Coronavirus Infections/drug therapy , Coronavirus Infections/prevention & control , Coronavirus Infections/therapy , Coronavirus Infections/transmission , Deception , Fomites , Genocide , Government Agencies , Health Personnel , Humans , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Pneumonia, Viral/therapy , Pneumonia, Viral/transmission , Politics , Quarantine , Research Personnel , Social Media
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