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1.
Viruses ; 14(4), 2022.
Article in English | EMBASE | ID: covidwho-1798882

ABSTRACT

Metapneumoviruses, members of the family Pneumoviridae, have been identified in birds (avian metapneumoviruses;AMPV’s) and humans (human metapneumoviruses;HMPV’s). AMPV and HMPV are closely related viruses with a similar genomic organization and cause respiratory tract illnesses in birds and humans, respectively. AMPV can be classified into four subgroups, A–D, and is the etiological agent of turkey rhinotracheitis and swollen head syndrome in chickens. Epidemiological studies have indicated that AMPV also circulates in wild bird species which may act as reservoir hosts for novel subtypes. HMPV was first discovered in 2001, but retrospective studies have shown that HMPV has been circulating in humans for at least 50 years. AMPV subgroup C is more closely related to HMPV than to any other AMPV subgroup, suggesting that HMPV has evolved from AMPV-C following zoonotic transfer. In this review, we present a historical perspective on the discovery of metapneumoviruses and discuss the host tropism, pathogenicity, and molecular characteristics of the different AMPV and HMPV subgroups to provide increased focus on the necessity to better understand the evolutionary pathways through which HMPV emerged as a seasonal endemic human respiratory virus.

2.
Water Res ; 212: 118112, 2022 Apr 01.
Article in English | MEDLINE | ID: covidwho-1636095

ABSTRACT

Viruses are present at low concentrations in wastewater; therefore, an effective method for concentrating virus particles is necessary for accurate wastewater-based epidemiology (WBE). We designed a novel approach to concentrate human and animal viruses from wastewater using porcine gastric mucin-conjugated magnetic beads (PGM-MBs). We systematically evaluated the performances of the PGM-MBs method (sensitivity, specificity, and robustness to environmental inhibitors) with six viral species, including Tulane virus (a surrogate for human norovirus), rotavirus, adenovirus, porcine coronavirus (transmissible gastroenteritis virus or TGEV), and two human coronaviruses (NL63 and SARS-CoV-2) in influent wastewater and raw sewage samples. We determined the multiplication factor (the ratio of genome concentration of the final solution to that of the initial solution) for the PGM-MBs method, which ranged from 1.3 to 64.0 depending on the viral species. Because the recovery efficiency was significantly higher when calculated with virus titers than it was with genome concentration, the PGM-MBs method could be an appropriate tool for assessing the risk to humans who are inadvertently exposed to wastewater contaminated with infectious viruses. Furthermore, PCR inhibitors were not concentrated by PGM-MBs, suggesting that this tool will be successful for use with environmental samples. In addition, the PGM-MBs method is cost-effective (0.5 USD/sample) and has a fast turnaround time (3 h from virus concentration to genome quantification). Thus, this method can be implemented in high throughput facilities. Because of its strong performance, intrinsic characteristics of targeting the infectious virus, robustness to wastewater, and adaptability to high throughput systems, the PGM-MBs method can be successfully applied to WBE and ultimately provides valuable public health information.


Subject(s)
COVID-19 , Viruses , Animals , Humans , Magnetic Phenomena , SARS-CoV-2 , Swine , Waste Water
3.
Virology ; 566: 106-113, 2022 01.
Article in English | MEDLINE | ID: covidwho-1550136

ABSTRACT

BACKGROUND: Krebs von den Lungen-6 (KL-6) is a molecule that is predominantly expressed by damaged alveolar type II cells, and has been proposed as a marker of COVID-19 and the severity of the disease. Here, we performed a meta-analysis to determine whether KL-6 could be used as a prognostic factor for severe COVID-19. METHODS: PubMed, Cochrane and Google Scholar were searched until April 20, 2021, and 7 studies were included. KL-6 was considered as the outcome and pooled in meta-analyses. RESULTS: All included studies compared KL-6 in severe and non-severe patients. Serum KL-6 was higher in severe COVID-19 patients compared to non-severe (n = 6; SMD = 1.25; 95% CI: 0.99-1.5; P < 0.001) and healthy controls (n = 4; SMD = 3.07; 95% CI: 1.36-4.8; P < 0.001). CONCLUSION: This data collection revealed the potential clinical significance of KL-6 as a non-expensive predictive biomarker in severe COVID-19 and for the categorization of COVID-19 clinical severity.


Subject(s)
COVID-19/blood , COVID-19/diagnosis , Mucin-1/blood , SARS-CoV-2 , Adult , Aged , Biomarkers/blood , Female , Humans , Male , Middle Aged , Prognosis , Severity of Illness Index
4.
Innate Immun ; 27(6): 423-436, 2021 08.
Article in English | MEDLINE | ID: covidwho-1409426

ABSTRACT

Both innate immunity and acquired immunity are involved in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. The induction of Abs that neutralize the virus has been described, and certain Abs against endemic coronaviruses may cross-react with SARS-CoV-2. Detailed mechanisms to protect against the pandemic of SARS-CoV-2 remain unresolved. We previously reported that IgG Fc-binding protein (Fcγbp), a unique, large molecular weight, and mucin-like secretory Fc receptor protein, secreted from goblet cells of human small and large intestine, mediates the transportation of serum IgG onto the mucosal surface. In this review, we show that mucous bronchial gland cells and some goblet cells are immunoreactive for Fcγbp. Fcγbp traps the cross-reactive (both neutralizing and non-neutralizing) IgG bound to the virus and can consequently eliminate the virus from the mucosal surface to decrease viral loads. Fcγbp can also suppress immune overreaction by interfering with Fc-binding by macrophages and competing with complement fixation. Fcγbp secreted from mucin-producing cells of the airway functions as an important anti-infection mucosal defense. The Fcγbp-mediated mechanism can be a key factor in explaining why SARS-CoV-2 is less infective/lethal in children, and may also be involved in the unique Ab response, recurrent infection, and effects of serum therapy and vaccination.


Subject(s)
Antibodies, Viral/immunology , Bronchi/cytology , COVID-19/immunology , Cell Adhesion Molecules/immunology , Antibodies, Neutralizing , Cross Reactions , Humans , Immunity, Innate , Immunoglobulin G , Mucins , SARS-CoV-2/immunology
5.
Vaccines (Basel) ; 9(6)2021 Jun 10.
Article in English | MEDLINE | ID: covidwho-1282654

ABSTRACT

Ebola virus (EBOV) is the cause of sporadic outbreaks of human hemorrhagic disease in Africa, and the best-characterized virus in the filovirus family. The West African epidemic accelerated the clinical development of vaccines and therapeutics, leading to licensure of vaccines and antibody-based therapeutics for human use in recent years. The most widely used vaccine is based on vesicular stomatitis virus (VSV) expressing the EBOV glycoprotein (GP) (VSV-EBOV). Due to its favorable immune cell targeting, this vaccine has also been used as a base vector for the development of second generation VSV-based vaccines against Influenza, Nipah, and Zika viruses. However, in these situations, it may be beneficial if the immunogenicity against EBOV GP is minimized to induce a better protective immune response against the other foreign immunogen. Here, we analyzed if EBOV GP can be truncated to be less immunogenic, yet still able to drive replication of the vaccine vector. We found that the EBOV GP glycan cap and the mucin-like domain are both dispensable for VSV-EBOV replication. The glycan cap, however, appears critical for mediating a protective immune response against lethal EBOV challenge in mice.

6.
Comput Struct Biotechnol J ; 19: 1654-1660, 2021.
Article in English | MEDLINE | ID: covidwho-1144575

ABSTRACT

Susceptibility to severe illness from COVID-19 is anticipated to be associated with cigarette smoking as it aggravates the risk of cardiovascular and respiratory illness, including infections. This is particularly important with the advent of a new strain of coronaviruses, the severe acute respiratory syndrome coronavirus (SARS-CoV-2) that has led to the present pandemic, coronavirus disease 2019 (COVID-19). Although, the effects of smoking on COVID-19 are less described and controversial, we presume a link between smoking and COVID-19. Smoking has been shown to enhance the expression of the angiotensin-converting enzyme-2 (ACE-2) and transmembrane serine protease 2 (TMPRSS2) key entry genes utilized by SARS-CoV-2 to infect cells and induce a 'cytokine storm', which further increases the severity of COVID-19 clinical course. Nevertheless, the impact of smoking on ACE-2 and TMPRSS2 receptors expression remains paradoxical. Thus, further research is necessary to unravel the association between smoking and COVID-19 and to pursue the development of potential novel therapies that are able to constrain the morbidity and mortality provoked by this infectious disease. Herein we present a brief overview of the current knowledge on the correlation between smoking and the expression of SARS-CoV-2 key entry genes, clinical manifestations, and disease progression.

7.
EBioMedicine ; 65: 103277, 2021 Mar.
Article in English | MEDLINE | ID: covidwho-1131243

ABSTRACT

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a complex lung disease, characterized by progressive lung scarring. Severe COVID-19 is associated with substantial pneumonitis and has a number of shared major risk factors with IPF. This study aimed to determine the genetic correlation between IPF and severe COVID-19 and assess a potential causal role of genetically increased risk of IPF on COVID-19 severity. METHODS: The genetic correlation between IPF and COVID-19 severity was estimated with linkage disequilibrium (LD) score regression. We performed a Mendelian randomization (MR) study for IPF causality in COVID-19. Genetic variants associated with IPF susceptibility (P<5 × 10-8) in previous genome-wide association studies (GWAS) were used as instrumental variables (IVs). Effect estimates of those IVs on COVID-19 severity were gathered from the GWAS meta-analysis by the COVID-19 Host Genetics Initiative (4,336 cases & 623,902 controls). FINDINGS: We detected a positive genetic correlation of IPF with COVID-19 severity (rg=0·31 [95% CI 0·04-0·57], P = 0·023). The MR estimates for severe COVID-19 did not reveal any genetic association (OR 1·05, [95% CI 0·92-1·20], P = 0·43). However, outlier analysis revealed that the IPF risk allele rs35705950 at MUC5B had a different effect compared with the other variants. When rs35705950 was excluded, MR results provided evidence that genetically increased risk of IPF has a causal effect on COVID-19 severity (OR 1·21, [95% CI 1·06-1·38], P = 4·24 × 10-3). Furthermore, the IPF risk-allele at MUC5B showed an apparent protective effect against COVID-19 hospitalization only in older adults (OR 0·86, [95% CI 0·73-1·00], P = 2·99 × 10-2) . INTERPRETATION: The strongest genetic determinant of IPF, rs35705950 at MUC5B, seems to confer protection against COVID-19, whereas the combined effect of all other IPF risk loci seem to confer risk of COVID-19 severity. The observed effect of rs35705950 could either be due to protective effects of mucin over-production on the airways or a consequence of selection bias due to (1) a patient group that is heavily enriched for the rs35705950 T undertaking strict self-isolation and/or (2) due to survival bias of the rs35705950 non-IPF risk allele carriers. Due to the diverse impact of IPF causal variants on SARS-CoV-2 infection, with a possible selection bias as an explanation, further investigation is needed to address this apparent paradox between variance at MUC5B and other IPF genetic risk factors. FUNDING: Novo Nordisk Foundation and Oak Foundation.


Subject(s)
COVID-19/pathology , Genetic Predisposition to Disease/genetics , Idiopathic Pulmonary Fibrosis/pathology , COVID-19/genetics , Genome-Wide Association Study , Humans , Idiopathic Pulmonary Fibrosis/genetics , Lung/pathology , Mucin-5B/genetics , Polymorphism, Single Nucleotide/genetics , Risk , SARS-CoV-2 , Severity of Illness Index
8.
Curr Med Chem ; 28(36): 7387-7399, 2021.
Article in English | MEDLINE | ID: covidwho-1085140

ABSTRACT

Mucous epithelia are protected by complex mucus barrier layers, which are part of the innate immune defense. Trefoil factor family peptides TFF1, TFF2, and TFF3 have lectin activities and are predominantly co-secreted together with mucins from these epithelia. TFF1 and TFF2 are mainly expressed in the gastric mucosa, whereas TFF3 is widely secreted from most mucous epithelia and their glands. TFF1 and TFF3 consist of a single TFF domain and an additional free 7th cysteine residue, whereas TFF2 contains two TFF domains. Systematic analyses of the molecular forms of TFFs gave new insights into their diverse molecular functions. TFF1 mainly exists as a monomer with an unusual free thiol group and only minor amounts form a disulfide-linked homodimer as well as heterodimers with gastrokine-2 and IgG-Fc-binding protein (FCGBP). TFF3 mainly forms a heterodimer with FCGBP in vivo, but also binds Deleted in Malignant Brain Tumors/gp340 (DMBT1gp340) in vitro. In contrast, TFF2 binds as a lectin to a conserved O-linked carbohydrate moiety of the mucin MUC6. Both FCGBP and DMBT1gp340 are secreted by most mucous epithelia and their glands and are involved in mucosal innate immunity. Thus, a new picture emerged pointing to functions of TFF3-FCGBP (and TFF1-FCGBP) for mucosal innate immune defense, e.g. supporting the clearing of the microorganisms. Such a function could be well be supported by DMBT1gp340. In contrast, the TFF2/MUC6 lectin complex probably physically stabilizes the inner adherent gastric mucus layer. Furthermore, there are indications that TFF3- FCGBP might also play a role in the blood vessels.


Subject(s)
Trefoil Factors , Calcium-Binding Proteins , DNA-Binding Proteins , Humans , Immunity, Innate , Peptides/metabolism , Trefoil Factor-1/metabolism , Trefoil Factor-2 , Trefoil Factors/metabolism , Tumor Suppressor Proteins
9.
Mar Drugs ; 19(2)2021 Jan 27.
Article in English | MEDLINE | ID: covidwho-1050622

ABSTRACT

Inorganic polyphosphate (polyP) is a widely distributed polymer found from bacteria to animals, including marine species. This polymer exhibits morphogenetic as well as antiviral activity and releases metabolic energy after enzymatic hydrolysis also in human cells. In the pathogenesis of the coronavirus disease 2019 (COVID-19), the platelets are at the frontline of this syndrome. Platelets release a set of molecules, among them polyP. In addition, the production of airway mucus, the first line of body defense, is impaired in those patients. Therefore, in this study, amorphous nanoparticles of the magnesium salt of polyP (Mg-polyP-NP), matching the size of the coronavirus SARS-CoV-2, were prepared and loaded with the secondary plant metabolite quercetin or with dexamethasone to study their effects on the respiratory epithelium using human alveolar basal epithelial A549 cells as a model. The results revealed that both compounds embedded into the polyP nanoparticles significantly increased the steady-state-expression of the MUC5AC gene. This mucin species is the major mucus glycoprotein present in the secreted gel-forming mucus. The level of gene expression caused by quercetin or with dexamethasone, if caged into polyP NP, is significantly higher compared to the individual drugs alone. Both quercetin and dexamethasone did not impair the growth-supporting effect of polyP on A549 cells even at concentrations of quercetin which are cytotoxic for the cells. A possible mechanism of the effects of the two drugs together with polyP on mucin expression is proposed based on the scavenging of free oxygen species and the generation of ADP/ATP from the polyP, which is needed for the organization of the protective mucin-based mucus layer.


Subject(s)
Anti-Inflammatory Agents/pharmacology , Antioxidants/pharmacology , Dexamethasone/pharmacology , Mucin 5AC/biosynthesis , Mucin 5AC/drug effects , Quercetin/pharmacology , A549 Cells , Anti-Inflammatory Agents/chemistry , Antioxidants/chemistry , COVID-19 , Dexamethasone/chemistry , Free Radical Scavengers/pharmacology , Gene Expression Regulation/drug effects , Humans , Magnesium/chemistry , Mucin 5AC/genetics , Mucins/biosynthesis , Mucins/chemistry , Nanoparticles , Particle Size , Plants/chemistry , Polyphosphates/chemistry , Quercetin/chemistry , Reactive Oxygen Species
10.
Mar Drugs ; 18(12)2020 Dec 14.
Article in English | MEDLINE | ID: covidwho-977761

ABSTRACT

The mucus layer of the nasopharynx and bronchial epithelium has a barrier function against inhaled pathogens such as the coronavirus SARS-CoV-2. We recently found that inorganic polyphosphate (polyP), a physiological, metabolic energy (ATP)-providing polymer released from blood platelets, blocks the binding of the receptor binding domain (RBD) to the cellular ACE2 receptor in vitro. PolyP is a marine natural product and is abundantly present in marine bacteria. Now, we have approached the in vivo situation by studying the effect of polyP on the human alveolar basal epithelial A549 cells in a mucus-like mucin environment. These cells express mucins as well as the ectoenzymes alkaline phosphatase (ALP) and adenylate kinase (ADK), which are involved in the extracellular production of ATP from polyP. Mucin, integrated into a collagen-based hydrogel, stimulated cell growth and attachment. The addition of polyP to the hydrogel significantly increased cell attachment and also the expression of the membrane-tethered mucin MUC1 and the secreted mucin MUC5AC. The increased synthesis of MUC1 was also confirmed by immunostaining. This morphogenetic effect of polyP was associated with a rise in extracellular ATP level. We conclude that the nontoxic and non-immunogenic polymer polyP could possibly also exert a protective effect against SARS-CoV-2-cell attachment; first, by stimulating the innate antiviral response by strengthening the mucin barrier with its antimicrobial proteins, and second, by inhibiting virus attachment to the cells, as deduced from the reduction in the strength of binding between the viral RBD and the cellular ACE2 receptor.


Subject(s)
Aquatic Organisms/metabolism , Biological Products/pharmacology , COVID-19/prevention & control , Polyphosphates/pharmacology , Respiratory Mucosa/drug effects , A549 Cells , Bacteria/metabolism , Biological Products/therapeutic use , COVID-19/virology , Humans , Immunity, Innate/drug effects , Mucin 5AC/metabolism , Mucin-1/metabolism , Polyphosphates/metabolism , Polyphosphates/therapeutic use , Respiratory Mucosa/immunology , Respiratory Mucosa/metabolism , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , Secondary Metabolism , Virus Attachment/drug effects
11.
mBio ; 11(6)2020 11 12.
Article in English | MEDLINE | ID: covidwho-922531

ABSTRACT

Mucus plays a pivotal role in protecting the respiratory tract against microbial infections. It acts as a primary contact site to entrap microbes and facilitates their removal from the respiratory tract via the coordinated beating of motile cilia. The major components of airway mucus are heavily O-glycosylated mucin glycoproteins, divided into gel-forming mucins and transmembrane mucins. The gel-forming mucins MUC5AC and MUC5B are the primary structural components of airway mucus, and they enable efficient clearance of pathogens by mucociliary clearance. MUC5B is constitutively expressed in the healthy airway, whereas MUC5AC is upregulated in response to inflammatory challenge. MUC1, MUC4, and MUC16 are the three major transmembrane mucins of the respiratory tracts which prevent microbial invasion, can act as releasable decoy receptors, and activate intracellular signal transduction pathways. Pathogens have evolved virulence factors such as adhesins that facilitate interaction with specific mucins and mucin glycans, for example, terminal sialic acids. Mucin expression and glycosylation are dependent on the inflammatory state of the respiratory tract and are directly regulated by proinflammatory cytokines and microbial ligands. Gender and age also impact mucin glycosylation and expression through the female sex hormone estradiol and age-related downregulation of mucin production. Here, we discuss what is currently known about the role of respiratory mucins and their glycans during bacterial and viral infections of the airways and their relevance for the novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Understanding the impact of microbe-mucin interaction in the respiratory tract could inspire the development of novel therapies to boost mucosal defense and combat respiratory infections.


Subject(s)
Glycoproteins/metabolism , Mucins/metabolism , Respiratory Tract Infections/microbiology , Respiratory Tract Infections/virology , Bacterial Infections/metabolism , COVID-19/virology , Glycosylation , Humans , Mucin 5AC/metabolism , Mucin-1/metabolism , Mucin-5B/metabolism , Respiratory Tract Infections/prevention & control , SARS-CoV-2/pathogenicity , Virus Diseases/metabolism
12.
Microb Risk Anal ; 16: 100140, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-779468

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Middle East respiratory syndrome coronavirus (MERS-CoV) infect the human respiratory tract. A prototype thermodynamic equilibrium model is presented here for the probability of the virions getting through the mucus barrier and infecting epithelial cells based on the binding affinity (Kmucin) of the virions to mucin molecules in the mucus and parameters for binding and infection of the epithelial cell. Both MERS-CoV and SARS-CoV-2 bind strongly to their cellular receptors, DDP4 and ACE2, respectively, and infect very efficiently both bronchus and lung ex vivo cell cultures which are not protected by a mucus barrier. According to the model, mucin binding could reduce the infectivity for MERS-CoV compared to SARS-CoV-2 by at least 100-fold depending on the magnitude of Kmucin. Specifically Kmucin values up to 106 M-1 have little protective effect and thus the mucus barrier would not remove SARS-CoV-2 which does not bind to sialic acids (SA) and hence would have a very low Kmucin. Depending on the viability of individual virions, the ID50 for SARS-CoV-2 is estimated to be ~500 virions (viral RNA genomic copies) representing 1 to 2 pfu. In contrast MERS-CoV binds both SA and human mucin and a Kmucin of 5 × 109 M-1 as reported for lectins would mop up 99.83% of the virus according to the model with the ID50 for MERS-CoV estimated to be ~295,000 virions (viral RNA genomic copies) representing 819 pfu. This could in part explain why MERS-CoV is poorly transmitted from human to human compared to SARS-CoV-2. Some coronaviruses use an esterase to escape the mucin, although MERS-CoV does not. Instead, it is shown here that "clustering" of virions into single aerosol particles as recently reported for rotavirus in extracellular vesicles could provide a co-operative mechanism whereby MERS-CoV could theoretically overcome the mucin barrier locally and a small proportion of 10 µm diameter aerosol particles could contain ~70 virions based on reported maximum levels in saliva. Although recent evidence suggests SARS-CoV-2 initiates infection in the nasal epithelium, the thermodynamic equilibrium models presented here could complement published approaches for modelling the physical entry of pathogens to the lung based on the fate and transport of the pathogen particles (as for anthrax spores) to develop a dose-response model for aerosol exposure to respiratory viruses. This would enable the infectivity through aerosols to be defined based on molecular parameters as well as physical parameters. The role of the spike proteins of MERS-CoV and SARS-CoV-2 binding to SA and heparan sulphate, respectively, may be to aid non-specific attachment to the host cell. It is proposed that a high Kmucin is the cost for subsequent binding of MERS-CoV to SAs on the cell surface to partially overcome the unfavourable entropy of immobilisation as the virus adopts the correct orientation for spike protein interactions with its protein cellular receptor DPP4.

13.
Bioinformation ; 16(3): 219-222, 2020.
Article in English | MEDLINE | ID: covidwho-100214

ABSTRACT

New evidence on the T-cell immuno-pathology in patient's with Corona Virus Disease 2019 (CoViD-19) was reported by Diao et al. in MedRxiv (doi: 10.1101/2020.02.18.20024364) [1]. It reports observations on 522 patients with confirmed CoViD-19 symptomatology, compared to 40 control subjects. In brief, notable T cytopoenia was recorded by flow cytometry in the CD4+ and the CD8+ populations, which were significantly yet inversely correlated with remarkably increased serum levels of the pro-inflammatory cytokines IL-6, IL-10 and TNF-a. Flow cytometry established a progressive increase in the expression of programmed cell death marker-1 (PD-1) and T cell immunoglobulin and mucin domain 3 (Tim-3) as patients (n=14) deteriorated from prodromal to symptomatic CoViD-19 requiring intensive care. Here, we interpret these observations of Diao et al from our current understanding of T cell immunophysiology and immunopathology following an immune challenge in the form of sustained viral infection, as is the case in CoViD-19, with emphasis on exhausted T cells (Tex). Recent clinical trials to rescue Tex show promising outcomes. The relevance of these interventions for the prevention and treatment of CoViD-19 is discussed. Taken together, the data of Diao et al could proffer the first glimpse of immunopathology and possible immunotherapy for patients with CoViD-19.

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