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1.
Viruses ; 12(6)2020 06 24.
Article in English | MEDLINE | ID: covidwho-620517

ABSTRACT

The respiratory Influenza A Viruses (IAVs) and emerging zoonotic viruses such as Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) pose a significant threat to human health. To accelerate our understanding of the host-pathogen response to respiratory viruses, the use of more complex in vitro systems such as normal human bronchial epithelial (NHBE) cell culture models has gained prominence as an alternative to animal models. NHBE cells were differentiated under air-liquid interface (ALI) conditions to form an in vitro pseudostratified epithelium. The responses of well-differentiated (wd) NHBE cells were examined following infection with the 2009 pandemic Influenza A/H1N1pdm09 strain or following challenge with the dsRNA mimic, poly(I:C). At 30 h postinfection with H1N1pdm09, the integrity of the airway epithelium was severely impaired and apical junction complex damage was exhibited by the disassembly of zona occludens-1 (ZO-1) from the cell cytoskeleton. wdNHBE cells produced an innate immune response to IAV-infection with increased transcription of pro- and anti-inflammatory cytokines and chemokines and the antiviral viperin but reduced expression of the mucin-encoding MUC5B, which may impair mucociliary clearance. Poly(I:C) produced similar responses to IAV, with the exception of MUC5B expression which was more than 3-fold higher than for control cells. This study demonstrates that wdNHBE cells are an appropriate ex-vivo model system to investigate the pathogenesis of respiratory viruses.


Subject(s)
Influenza A Virus, H1N1 Subtype/physiology , Influenza, Human/virology , Respiratory Mucosa/cytology , Respiratory Mucosa/virology , Animals , Bronchi/cytology , Bronchi/virology , Cells, Cultured , Chemokines/metabolism , Cytokines/metabolism , Dogs , Host-Pathogen Interactions , Humans , Immunity, Innate , Influenza A Virus, H1N1 Subtype/immunology , Influenza, Human/epidemiology , Intercellular Junctions , Madin Darby Canine Kidney Cells , Models, Biological , Mucin 5AC/metabolism , Pandemics , Virus Cultivation
2.
Int J Mol Sci ; 21(16)2020 Aug 07.
Article in English | MEDLINE | ID: covidwho-714483

ABSTRACT

Sensitive molecular assays are critical for coronavirus disease 2019 (COVID-19) diagnosis. Here, we designed and evaluated two single-tube nested (STN) real-time RT-PCR assays, targeting SARS-CoV-2 RdRp/Hel and N genes. Both STN assays had a low limit of detection and did not cross react with other human coronaviruses and respiratory viruses. Using 213 initial respiratory specimens from suspected COVID-19 patients, the sensitivity of both the STN COVID-19-RdRp/Hel and the STN COVID-19-N assays was 100% (99/99), while that of the comparator non-nested N assay was 95% (94/99). Among 108 follow-up specimens from confirmed COVID-19 patients who tested negative by the non-nested COVID-19-RdRp/Hel assay, 28 (25.9%) were positive for SARS-CoV-2 by the STN COVID-19-RdRp/Hel or the STN COVID-19-N assay. To evaluate the performance of our novel STN assays in pooled specimens, we created four sample pools, with each pool consisting of one low positive specimen and 49 negative specimens. While the non-nested COVID-19-RdRp/Hel assay was positive in only one of four sample pools (25%), both of the STN assays were positive in two of four samples pools (50%). In conclusion, the STN assays are highly sensitive and specific for SARS-CoV-2 detection. Their boosted sensitivity offers advantages in non-traditional COVID-19 testing algorithms such as saliva screening and pooled sample screening during massive screening.


Subject(s)
Betacoronavirus/genetics , Coronavirus Infections/virology , Molecular Diagnostic Techniques/methods , Pneumonia, Viral/virology , Real-Time Polymerase Chain Reaction/methods , Betacoronavirus/pathogenicity , Coronavirus Infections/diagnosis , Humans , Molecular Diagnostic Techniques/standards , Nucleocapsid Proteins/genetics , Pandemics , Pneumonia, Viral/diagnosis , RNA Replicase/genetics , Real-Time Polymerase Chain Reaction/standards , Respiratory Mucosa/virology , Sensitivity and Specificity , Viral Nonstructural Proteins/genetics
3.
PLoS Biol ; 18(8): e3000815, 2020 08.
Article in English | MEDLINE | ID: covidwho-712731

ABSTRACT

Two illustrations integrate current knowledge about severe acute respiratory syndrome (SARS) coronaviruses and their life cycle. They have been widely used in education and outreach through free distribution as part of a coronavirus-related resource at Protein Data Bank (PDB)-101, the education portal of the RCSB PDB. Scientific sources for creation of the illustrations and examples of dissemination and response are presented.


Subject(s)
Betacoronavirus/growth & development , Biomedical Research/education , Coronavirus Infections/prevention & control , Databases, Protein , Medicine in the Arts , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Animals , Betacoronavirus/physiology , Biomedical Research/methods , Coronavirus Infections/epidemiology , Coronavirus Infections/virology , Data Display , Humans , Information Dissemination/methods , Life Cycle Stages , Pneumonia, Viral/epidemiology , Pneumonia, Viral/virology , Respiratory Mucosa/virology
4.
J Virol ; 94(15)2020 07 16.
Article in English | MEDLINE | ID: covidwho-690841

ABSTRACT

Currently, there are four seasonal coronaviruses associated with relatively mild respiratory tract disease in humans. However, there is also a plethora of animal coronaviruses which have the potential to cross the species border. This regularly results in the emergence of new viruses in humans. In 2002, severe acute respiratory syndrome coronavirus (SARS-CoV) emerged and rapidly disappeared in May 2003. In 2012, Middle East respiratory syndrome coronavirus (MERS-CoV) was identified as a possible threat to humans, but its pandemic potential so far is minimal, as human-to-human transmission is ineffective. The end of 2019 brought us information about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emergence, and the virus rapidly spread in 2020, causing an unprecedented pandemic. At present, studies on the virus are carried out using a surrogate system based on the immortalized simian Vero E6 cell line. This model is convenient for diagnostics, but it has serious limitations and does not allow for understanding of the biology and evolution of the virus. Here, we show that fully differentiated human airway epithelium cultures constitute an excellent model to study infection with the novel human coronavirus SARS-CoV-2. We observed efficient replication of the virus in the tissue, with maximal replication at 2 days postinfection. The virus replicated in ciliated cells and was released apically.IMPORTANCE Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged by the end of 2019 and rapidly spread in 2020. At present, it is of utmost importance to understand the biology of the virus, rapidly assess the treatment potential of existing drugs, and develop new active compounds. While some animal models for such studies are under development, most of the research is carried out in Vero E6 cells. Here, we propose fully differentiated human airway epithelium cultures as a model for studies on SARS-CoV-2.


Subject(s)
Betacoronavirus/physiology , Coronavirus Infections/virology , Pneumonia, Viral/virology , Respiratory Mucosa/virology , Severe Acute Respiratory Syndrome/virology , Virus Replication , Animals , Cell Line , Cells, Cultured , Chlorocebus aethiops , Humans , Pandemics , Vero Cells
5.
Mol Syst Biol ; 16(7): e9841, 2020 07.
Article in English | MEDLINE | ID: covidwho-680520

ABSTRACT

Infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) leads to coronavirus disease 2019 (COVID-19), which poses an unprecedented worldwide health crisis, and has been declared a pandemic by the World Health Organization (WHO) on March 11, 2020. The angiotensin converting enzyme 2 (ACE2) has been suggested to be the key protein used by SARS-CoV-2 for host cell entry. In their recent work, Lindskog and colleagues (Hikmet et al, 2020) report that ACE2 is expressed at very low protein levels-if at all-in respiratory epithelial cells. Severe COVID-19, however, is characterized by acute respiratory distress syndrome and extensive damage to the alveoli in the lung parenchyma. Then, what is the role of the airway epithelium in the early stages of COVID-19, and which cells need to be studied to characterize the biological mechanisms responsible for the progression to severe disease after initial infection by the novel coronavirus?


Subject(s)
Coronavirus Infections/metabolism , Coronavirus Infections/virology , Peptidyl-Dipeptidase A/metabolism , Pneumonia, Viral/metabolism , Pneumonia, Viral/virology , Respiratory Mucosa/metabolism , Respiratory Mucosa/virology , Severe Acute Respiratory Syndrome/metabolism , Severe Acute Respiratory Syndrome/virology , Betacoronavirus , Conjunctiva/metabolism , Coronavirus Infections/enzymology , Host Microbial Interactions/genetics , Humans , Organ Specificity , Pandemics , Peptidyl-Dipeptidase A/genetics , Pneumonia, Viral/enzymology , Severe Acute Respiratory Syndrome/enzymology , Spike Glycoprotein, Coronavirus/metabolism
6.
Int J Mol Sci ; 21(14)2020 Jul 11.
Article in English | MEDLINE | ID: covidwho-646205

ABSTRACT

Recently, the world has been dealing with a devastating global pandemic coronavirus infection, with more than 12 million infected worldwide and over 300,000 deaths as of May 15th 2020, related to a novel coronavirus (2019-nCoV), characterized by a spherical morphology and identified through next-generation sequencing. Although the respiratory tract is the primary portal of entry of SARS-CoV-2, gastrointestinal involvement associated with nausea, vomiting and diarrhoea may also occur. No drug or vaccine has been approved due to the absence of evidence deriving from rigorous clinical trials. Increasing interest has been highlighted on the possible preventative role and adjunct treatment of lactoferrin, glycoprotein of human secretions part of a non-specific defensive system, known to play a crucial role against microbial and viral infections and exerting anti-inflammatory effects on different mucosal surfaces and able to regulate iron metabolism. In this review, analysing lactoferrin properties, we propose designing a clinical trial to evaluate and verify its effect using a dual combination treatment with local, solubilized intranasal spray formulation and oral administration. Lactoferrin could counteract the coronavirus infection and inflammation, acting either as natural barrier of both respiratory and intestinal mucosa or reverting the iron disorders related to the viral colonization.


Subject(s)
Coronavirus Infections/prevention & control , Lactoferrin/therapeutic use , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Betacoronavirus/isolation & purification , Betacoronavirus/physiology , Coronavirus Infections/pathology , Coronavirus Infections/virology , Humans , Inflammation , Intestinal Mucosa/drug effects , Intestinal Mucosa/virology , Iron/metabolism , Lactoferrin/pharmacology , Peptidyl-Dipeptidase A/metabolism , Pneumonia, Viral/pathology , Pneumonia, Viral/virology , Respiratory Mucosa/drug effects , Respiratory Mucosa/virology , Virus Internalization/drug effects
7.
Am J Physiol Lung Cell Mol Physiol ; 319(1): L115-L120, 2020 07 01.
Article in English | MEDLINE | ID: covidwho-558506

ABSTRACT

COVID-19 can be divided into three clinical stages, and one can speculate that these stages correlate with where the infection resides. For the asymptomatic phase, the infection mostly resides in the nose, where it elicits a minimal innate immune response. For the mildly symptomatic phase, the infection is mostly in the pseudostratified epithelium of the larger airways and is accompanied by a more vigorous innate immune response. In the conducting airways, the epithelium can recover from the infection, because the keratin 5 basal cells are spared and they are the progenitor cells for the bronchial epithelium. There may be more severe disease in the bronchioles, where the club cells are likely infected. The devastating third phase is in the gas exchange units of the lung, where ACE2-expressing alveolar type II cells and perhaps type I cells are infected. The loss of type II cells results in respiratory insufficiency due to the loss of pulmonary surfactant, alveolar flooding, and possible loss of normal repair, since type II cells are the progenitors of type I cells. The loss of type I and type II cells will also block normal active resorption of alveolar fluid. Subsequent endothelial damage leads to transudation of plasma proteins, formation of hyaline membranes, and an inflammatory exudate, characteristic of ARDS. Repair might be normal, but if the type II cells are severely damaged alternative pathways for epithelial repair may be activated, which would result in some residual lung disease.


Subject(s)
Alveolar Epithelial Cells/virology , Betacoronavirus/pathogenicity , Coronavirus Infections/virology , Epithelial Cells/virology , Pneumonia, Viral/virology , Alveolar Epithelial Cells/metabolism , Coronavirus Infections/diagnosis , Coronavirus Infections/therapy , Epithelial Cells/metabolism , Epithelium/metabolism , Epithelium/virology , Humans , Lung/metabolism , Pandemics , Pneumonia, Viral/diagnosis , Pneumonia, Viral/therapy , Respiratory Mucosa/metabolism , Respiratory Mucosa/virology
8.
Int J Mol Sci ; 21(11)2020 May 28.
Article in English | MEDLINE | ID: covidwho-487805

ABSTRACT

Mucociliary clearance, mediated by a coordinated function of cilia bathing in the airway surface liquid (ASL) on the surface of airway epithelium, protects the host from inhaled pathogens and is an essential component of the innate immunity. ASL is composed of the superficial mucus layer and the deeper periciliary liquid. Ion channels, transporters, and pumps coordinate the transcellular and paracellular movement of ions and water to maintain the ASL volume and mucus hydration. microRNA (miRNA) is a class of non-coding, short single-stranded RNA regulating gene expression by post-transcriptional mechanisms. miRNAs have been increasingly recognized as essential regulators of ion channels and transporters responsible for ASL homeostasis. miRNAs also influence the airway host defense. We summarize the most up-to-date information on the role of miRNAs in ASL homeostasis and host-pathogen interactions in the airway and discuss concepts for miRNA-directed therapy.


Subject(s)
Coronaviridae Infections/metabolism , Host-Pathogen Interactions , MicroRNAs/genetics , Respiratory Mucosa/metabolism , Respiratory Tract Absorption , Animals , Coronaviridae Infections/genetics , Coronaviridae Infections/virology , Homeostasis , Humans , MicroRNAs/metabolism , Respiratory Mucosa/virology
9.
Eur Ann Otorhinolaryngol Head Neck Dis ; 137(4): 291-296, 2020 Sep.
Article in English | MEDLINE | ID: covidwho-437020

ABSTRACT

The influenza virus and SARS-CoV-2 cause trivial upper and severe lower respiratory infections (Influenza virus 290,000 to 650,000 deaths/year). These viruses come into contact with the airways either by direct projection, by secondary inhalation of airborne droplets, or by handling (fomites). The objective of this article is to clarify the mechanisms of production and penetration of droplets of secretions emitted during all expiratory phenomena likely to transport these viruses and come into contact with the respiratory mucosa. The droplets>5µm follow the laws of ballistics, those<5µm follow Brownian motion and remain suspended in the air. The aerosols of droplets are very heterogeneous whether the subject is healthy or sick. During an infectious period, not all droplets contain viral RNA. If these RNAs are detectable around patients, on surfaces, and in the ambient air at variable distances according to the studies (from 0.5m to beyond the patient's room), this is without prejudice to the infectious nature (viability) of the virus and the minimum infectious dose. There is a time lag between the patient's infectious period and that of RNA detection for both viruses. Subsequently, the inhaled particles must meet the laws of fluid dynamics (filtration) to settle in the respiratory tree. All of this partly explains the contagiousness and the clinical expression of these two viruses from the olfactory cleft to the alveoli.


Subject(s)
Betacoronavirus/pathogenicity , Bodily Secretions/virology , Coronavirus Infections/transmission , Influenza, Human/transmission , Orthomyxoviridae/pathogenicity , Otolaryngology , Pneumonia, Viral/transmission , Respiratory Mucosa/virology , Aerosols , Betacoronavirus/genetics , Humans , Orthomyxoviridae/genetics , Pandemics , RNA, Viral/analysis
10.
J Virol ; 94(15)2020 07 16.
Article in English | MEDLINE | ID: covidwho-324338

ABSTRACT

Currently, there are four seasonal coronaviruses associated with relatively mild respiratory tract disease in humans. However, there is also a plethora of animal coronaviruses which have the potential to cross the species border. This regularly results in the emergence of new viruses in humans. In 2002, severe acute respiratory syndrome coronavirus (SARS-CoV) emerged and rapidly disappeared in May 2003. In 2012, Middle East respiratory syndrome coronavirus (MERS-CoV) was identified as a possible threat to humans, but its pandemic potential so far is minimal, as human-to-human transmission is ineffective. The end of 2019 brought us information about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emergence, and the virus rapidly spread in 2020, causing an unprecedented pandemic. At present, studies on the virus are carried out using a surrogate system based on the immortalized simian Vero E6 cell line. This model is convenient for diagnostics, but it has serious limitations and does not allow for understanding of the biology and evolution of the virus. Here, we show that fully differentiated human airway epithelium cultures constitute an excellent model to study infection with the novel human coronavirus SARS-CoV-2. We observed efficient replication of the virus in the tissue, with maximal replication at 2 days postinfection. The virus replicated in ciliated cells and was released apically.IMPORTANCE Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged by the end of 2019 and rapidly spread in 2020. At present, it is of utmost importance to understand the biology of the virus, rapidly assess the treatment potential of existing drugs, and develop new active compounds. While some animal models for such studies are under development, most of the research is carried out in Vero E6 cells. Here, we propose fully differentiated human airway epithelium cultures as a model for studies on SARS-CoV-2.


Subject(s)
Betacoronavirus/physiology , Coronavirus Infections/virology , Pneumonia, Viral/virology , Respiratory Mucosa/virology , Severe Acute Respiratory Syndrome/virology , Virus Replication , Animals , Cell Line , Cells, Cultured , Chlorocebus aethiops , Humans , Pandemics , Vero Cells
11.
Lab Med ; 51(4): e45-e46, 2020 Jul 08.
Article in English | MEDLINE | ID: covidwho-209778

ABSTRACT

The recent SARS-CoV-2 outbreak has placed immense pressure on supply chains, including shortages in nasopharyngeal (NP) swabs. Here, we report our experience of using 3D-printing to rapidly develop and deploy custom-made NP swabs to address supply shortages at our healthcare institution.


Subject(s)
Clinical Laboratory Techniques/instrumentation , Diagnostic Equipment/supply & distribution , Nasopharynx/pathology , Printing, Three-Dimensional , Biopsy/instrumentation , Clinical Laboratory Techniques/methods , Coronavirus Infections/diagnosis , Diagnostic Equipment/standards , Disposable Equipment/standards , Disposable Equipment/supply & distribution , Humans , Nasopharynx/virology , Respiratory Mucosa/pathology , Respiratory Mucosa/virology
12.
Lancet Respir Med ; 8(7): 687-695, 2020 07.
Article in English | MEDLINE | ID: covidwho-197584

ABSTRACT

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in December 2019, causing a respiratory disease (coronavirus disease 2019, COVID-19) of varying severity in Wuhan, China, and subsequently leading to a pandemic. The transmissibility and pathogenesis of SARS-CoV-2 remain poorly understood. We evaluate its tissue and cellular tropism in human respiratory tract, conjunctiva, and innate immune responses in comparison with other coronavirus and influenza virus to provide insights into COVID-19 pathogenesis. METHODS: We isolated SARS-CoV-2 from a patient with confirmed COVID-19, and compared virus tropism and replication competence with SARS-CoV, Middle East respiratory syndrome-associated coronavirus (MERS-CoV), and 2009 pandemic influenza H1N1 (H1N1pdm) in ex-vivo cultures of human bronchus (n=5) and lung (n=4). We assessed extrapulmonary infection using ex-vivo cultures of human conjunctiva (n=3) and in-vitro cultures of human colorectal adenocarcinoma cell lines. Innate immune responses and angiotensin-converting enzyme 2 expression were investigated in human alveolar epithelial cells and macrophages. In-vitro studies included the highly pathogenic avian influenza H5N1 virus (H5N1) and mock-infected cells as controls. FINDINGS: SARS-CoV-2 infected ciliated, mucus-secreting, and club cells of bronchial epithelium, type 1 pneumocytes in the lung, and the conjunctival mucosa. In the bronchus, SARS-CoV-2 replication competence was similar to MERS-CoV, and higher than SARS-CoV, but lower than H1N1pdm. In the lung, SARS-CoV-2 replication was similar to SARS-CoV and H1N1pdm, but was lower than MERS-CoV. In conjunctiva, SARS-CoV-2 replication was greater than SARS-CoV. SARS-CoV-2 was a less potent inducer of proinflammatory cytokines than H5N1, H1N1pdm, or MERS-CoV. INTERPRETATION: The conjunctival epithelium and conducting airways appear to be potential portals of infection for SARS-CoV-2. Both SARS-CoV and SARS-CoV-2 replicated similarly in the alveolar epithelium; SARS-CoV-2 replicated more extensively in the bronchus than SARS-CoV. These findings provide important insights into the transmissibility and pathogenesis of SARS-CoV-2 infection and differences with other respiratory pathogens. FUNDING: US National Institute of Allergy and Infectious Diseases, University Grants Committee of Hong Kong Special Administrative Region, China; Health and Medical Research Fund, Food and Health Bureau, Government of Hong Kong Special Administrative Region, China.


Subject(s)
Betacoronavirus/immunology , Conjunctiva/virology , Coronavirus Infections/immunology , Immunity, Innate/immunology , Pneumonia, Viral/immunology , Respiratory System/virology , Viral Tropism/physiology , Virus Replication/physiology , Adult , Aged , Aged, 80 and over , Betacoronavirus/physiology , Conjunctiva/immunology , Conjunctiva/physiopathology , Coronavirus Infections/physiopathology , Female , Humans , Male , Middle Aged , Pandemics , Pneumonia, Viral/physiopathology , Respiratory Mucosa/immunology , Respiratory Mucosa/physiopathology , Respiratory Mucosa/virology , Respiratory System/immunology , Respiratory System/physiopathology
13.
Science ; 369(6499): 50-54, 2020 07 03.
Article in English | MEDLINE | ID: covidwho-154670

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause coronavirus disease 2019 (COVID-19), an influenza-like disease that is primarily thought to infect the lungs with transmission through the respiratory route. However, clinical evidence suggests that the intestine may present another viral target organ. Indeed, the SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) is highly expressed on differentiated enterocytes. In human small intestinal organoids (hSIOs), enterocytes were readily infected by SARS-CoV and SARS-CoV-2, as demonstrated by confocal and electron microscopy. Enterocytes produced infectious viral particles, whereas messenger RNA expression analysis of hSIOs revealed induction of a generic viral response program. Therefore, the intestinal epithelium supports SARS-CoV-2 replication, and hSIOs serve as an experimental model for coronavirus infection and biology.


Subject(s)
Betacoronavirus/physiology , Enterocytes/virology , Ileum/virology , Virus Replication , Betacoronavirus/ultrastructure , Cell Culture Techniques , Cell Differentiation , Cell Lineage , Cell Proliferation , Culture Media , Enterocytes/metabolism , Enterocytes/ultrastructure , Gene Expression , Humans , Ileum/metabolism , Ileum/ultrastructure , Lung/virology , Male , Organoids , Peptidyl-Dipeptidase A/genetics , Peptidyl-Dipeptidase A/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Receptors, Virus/genetics , Receptors, Virus/metabolism , Respiratory Mucosa/virology , SARS Virus/physiology
14.
Rev Esp Enferm Dig ; 112(5): 383-388, 2020 05.
Article in English | MEDLINE | ID: covidwho-148632

ABSTRACT

Although SARS-CoV-2 may primarily enter the cells of the lungs, the small bowel may also be an important entry or interaction site, as the enterocytes are rich in angiotensin converting enzyme (ACE)-2 receptors. The initial gastrointestinal symptoms that appear early during the course of Covid-19 support this hypothesis. Furthermore, SARS-CoV virions are preferentially released apically and not at the basement of the airway cells. Thus, in the setting of a productive infection of conducting airway epithelia, the apically released SARS-CoV may be removed by mucociliary clearance and gain access to the GI tract via a luminal exposure. In addition, post-mortem studies of mice infected by SARS-CoV have demonstrated diffuse damage to the GI tract, with the small bowel showing signs of enterocyte desquamation, edema, small vessel dilation and lymphocyte infiltration, as well as mesenteric nodes with severe hemorrhage and necrosis. Finally, the small bowel is rich in furin, a serine protease which can separate the S-spike of the coronavirus into two "pinchers" (S1 and 2). The separation of the S-spike into S1 and S2 is essential for the attachment of the virion to both the ACE receptor and the cell membrane. In this special review, we describe the interaction of SARS-CoV-2 with the cell and enterocyte and its potential clinical implications.


Subject(s)
Betacoronavirus/pathogenicity , Coronavirus Infections/metabolism , Enterocytes/virology , Gastrointestinal Diseases/virology , Intestine, Small/virology , Peptidyl-Dipeptidase A/metabolism , Pneumonia, Viral/metabolism , Betacoronavirus/metabolism , Coronavirus Infections/virology , Enterocytes/metabolism , Gastrointestinal Diseases/metabolism , Humans , Intestine, Small/cytology , Intestine, Small/metabolism , Pandemics , Pneumonia, Viral/virology , Receptors, Angiotensin/metabolism , Respiratory Mucosa/physiology , Respiratory Mucosa/virology
15.
ACS Chem Neurosci ; 11(9): 1200-1203, 2020 05 06.
Article in English | MEDLINE | ID: covidwho-47704

ABSTRACT

The novel SARS-CoV-2 virus has very high infectivity, which allows it to spread rapidly around the world. Attempts at slowing the pandemic at this stage depend on the number and quality of diagnostic tests performed. We propose that the olfactory epithelium from the nasal cavity may be a more appropriate tissue for detection of SARS-CoV-2 virus at the earliest stages, prior to onset of symptoms or even in asymptomatic people, as compared to commonly used sputum or nasopharyngeal swabs. Here we emphasize that the nasal cavity olfactory epithelium is the likely site of enhanced binding of SARS-CoV-2. Multiple non-neuronal cell types present in the olfactory epithelium express two host receptors, ACE2 and TMPRSS2 proteases, that facilitate SARS-CoV-2 binding, replication, and accumulation. This may be the underlying mechanism for the recently reported cases of smell dysfunction in patients with COVID-19. Moreover, the possibility of subsequent brain infection should be considered which begins in olfactory neurons. In addition, we discuss the possibility that olfactory receptor neurons may initiate rapid immune responses at early stages of the disease. We emphasize the need to undertake research focused on additional aspects of SARS-CoV-2 actions in the nervous system, especially in the olfactory pathway.


Subject(s)
Betacoronavirus/isolation & purification , Brain/virology , Coronavirus Infections/diagnosis , Early Diagnosis , Mass Screening/methods , Olfactory Mucosa/virology , Pneumonia, Viral/diagnosis , Smell , Animals , Betacoronavirus/growth & development , Betacoronavirus/immunology , Brain/immunology , Brain/physiopathology , Coronavirus Infections/immunology , Coronavirus Infections/physiopathology , Coronavirus Infections/transmission , Humans , Immunity, Innate , Mass Screening/standards , Mice , Olfactory Mucosa/cytology , Olfactory Mucosa/immunology , Olfactory Mucosa/metabolism , Olfactory Receptor Neurons/immunology , Olfactory Receptor Neurons/metabolism , Olfactory Receptor Neurons/virology , Pandemics , Peptidyl-Dipeptidase A/metabolism , Pneumonia, Viral/immunology , Pneumonia, Viral/physiopathology , Pneumonia, Viral/transmission , Respiratory Mucosa/metabolism , Respiratory Mucosa/virology , Serine Endopeptidases/metabolism , Virus Replication
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