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1.
Viruses ; 13(12)2021 12 06.
Article in English | MEDLINE | ID: covidwho-1555020

ABSTRACT

Porcine deltacoronavirus (PDCoV) is a novel coronavirus that causes diarrhea in nursing piglets. Studies showed that PDCoV uses porcine aminopeptidase N (pAPN) as an entry receptor, but the infection of pAPN-knockout cells or pigs with PDCoV revealed that pAPN might be not a critical functional receptor, implying there exists an unidentified receptor involved in PDCoV infection. Herein, we report that sialic acid (SA) can act as an attachment receptor for PDCoV invasion and facilitate its infection. We first demonstrated that the carbohydrates destroyed on the cell membrane using NaIO4 can alleviate the susceptibility of cells to PDCoV. Further study showed that the removal of SA, a typical cell-surface carbohydrate, could influence the PDCoV infectivity to the cells significantly, suggesting that SA was involved in the infection. The results of plaque assay and Western blotting revealed that SA promoted PDCoV infection by increasing the number of viruses binding to SA on the cell surface during the adsorption phase, which was also confirmed by atomic force microscopy at the microscopic level. In in vivo experiments, we found that the distribution levels of PDCoV and SA were closely relevant in the swine intestine, which contains huge amount of trypsin. We further confirmed that SA-binding capacity to PDCoV is related to the pre-treatment of PDCoV with trypsin. In conclusion, SA is a novel attachment receptor for PDCoV infection to enhance its attachment to cells, which is dependent on the pre-treatment of trypsin on PDCoV. This study paves the way for dissecting the mechanisms of PDCoV-host interactions and provides new strategies to control PDCoV infection.


Subject(s)
Deltacoronavirus/physiology , N-Acetylneuraminic Acid/metabolism , Receptors, Virus/metabolism , Trypsin/metabolism , Virus Attachment , Animals , Carbohydrates , Cell Line , Cell Membrane/metabolism , Cell Membrane/virology , Coronavirus Infections/veterinary , Coronavirus Infections/virology , Deltacoronavirus/drug effects , Host-Pathogen Interactions , Intestines/metabolism , Intestines/virology , Periodic Acid/pharmacology , Swine , Swine Diseases/virology , Trypsin/pharmacology
2.
Int J Mol Sci ; 22(11)2021 May 29.
Article in English | MEDLINE | ID: covidwho-1389398

ABSTRACT

Trypsin-like proteases (TLPs) belong to a family of serine enzymes with primary substrate specificities for the basic residues, lysine and arginine, in the P1 position. Whilst initially perceived as soluble enzymes that are extracellularly secreted, a number of novel TLPs that are anchored in the cell membrane have since been discovered. Muco-obstructive lung diseases (MucOLDs) are characterised by the accumulation of hyper-concentrated mucus in the small airways, leading to persistent inflammation, infection and dysregulated protease activity. Although neutrophilic serine proteases, particularly neutrophil elastase, have been implicated in the propagation of inflammation and local tissue destruction, it is likely that the serine TLPs also contribute to various disease-relevant processes given the roles that a number of these enzymes play in the activation of both the epithelial sodium channel (ENaC) and protease-activated receptor 2 (PAR2). More recently, significant attention has focused on the activation of viruses such as SARS-CoV-2 by host TLPs. The purpose of this review was to highlight key TLPs linked to the activation of ENaC and PAR2 and their association with airway dehydration and inflammatory signalling pathways, respectively. The role of TLPs in viral infectivity will also be discussed in the context of the inhibition of TLP activities and the potential of these proteases as therapeutic targets.


Subject(s)
COVID-19/enzymology , Lung Diseases, Obstructive/enzymology , SARS-CoV-2/metabolism , Trypsin/metabolism , Animals , COVID-19/pathology , Epithelial Sodium Channels/metabolism , Humans , Lung Diseases, Obstructive/pathology , Receptor, PAR-2/metabolism
3.
J Biol Chem ; 295(36): 12686-12696, 2020 09 04.
Article in English | MEDLINE | ID: covidwho-1387615

ABSTRACT

Type II transmembrane serine proteases (TTSPs) are a group of enzymes participating in diverse biological processes. Some members of the TTSP family are implicated in viral infection. TMPRSS11A is a TTSP expressed on the surface of airway epithelial cells, which has been shown to cleave and activate spike proteins of the severe acute respiratory syndrome (SARS) and the Middle East respiratory syndrome coronaviruses (CoVs). In this study, we examined the mechanism underlying the activation cleavage of TMPRSS11A that converts the one-chain zymogen to a two-chain enzyme. By expression in human embryonic kidney 293, esophageal EC9706, and lung epithelial A549 and 16HBE cells, Western blotting, and site-directed mutagenesis, we found that the activation cleavage of human TMPRSS11A was mediated by autocatalysis. Moreover, we found that TMPRSS11A activation cleavage occurred before the protein reached the cell surface, as indicated by studies with trypsin digestion to remove cell surface proteins, treatment with cell organelle-disturbing agents to block intracellular protein trafficking, and analysis of a soluble form of TMPRSS11A without the transmembrane domain. We also showed that TMPRSS11A was able to cleave the SARS-CoV-2 spike protein. These results reveal an intracellular autocleavage mechanism in TMPRSS11A zymogen activation, which differs from the extracellular zymogen activation reported in other TTSPs. These findings provide new insights into the diverse mechanisms in regulating TTSP activation.


Subject(s)
Epithelial Cells/metabolism , Membrane Proteins/metabolism , Proteolysis , Serine Proteases/metabolism , A549 Cells , Cells, Cultured , HEK293 Cells , Humans , Membrane Proteins/chemistry , Membrane Proteins/genetics , Mutation , Protein Domains , Protein Transport , Respiratory Mucosa/cytology , Serine Proteases/chemistry , Serine Proteases/genetics , Spike Glycoprotein, Coronavirus/metabolism , Trypsin/metabolism
5.
Biosci Rep ; 41(8)2021 08 27.
Article in English | MEDLINE | ID: covidwho-1334001

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2)-induced infection, the cause of coronavirus disease 2019 (COVID-19), is characterized by unprecedented clinical pathologies. One of the most important pathologies, is hypercoagulation and microclots in the lungs of patients. Here we study the effect of isolated SARS-CoV-2 spike protein S1 subunit as potential inflammagen sui generis. Using scanning electron and fluorescence microscopy as well as mass spectrometry, we investigate the potential of this inflammagen to interact with platelets and fibrin(ogen) directly to cause blood hypercoagulation. Using platelet-poor plasma (PPP), we show that spike protein may interfere with blood flow. Mass spectrometry also showed that when spike protein S1 is added to healthy PPP, it results in structural changes to ß and γ fibrin(ogen), complement 3, and prothrombin. These proteins were substantially resistant to trypsinization, in the presence of spike protein S1. Here we suggest that, in part, the presence of spike protein in circulation may contribute to the hypercoagulation in COVID-19 positive patients and may cause substantial impairment of fibrinolysis. Such lytic impairment may result in the persistent large microclots we have noted here and previously in plasma samples of COVID-19 patients. This observation may have important clinical relevance in the treatment of hypercoagulability in COVID-19 patients.


Subject(s)
COVID-19/pathology , Fibrin/metabolism , Fibrinolysis/physiology , Spike Glycoprotein, Coronavirus/metabolism , Thrombosis/pathology , Adult , Aged , Amyloid/metabolism , Blood Platelets/metabolism , Complement C3/metabolism , Female , Fibrinogen/metabolism , Humans , Lung/pathology , Male , Microfluidic Analytical Techniques , Middle Aged , Prothrombin/metabolism , SARS-CoV-2/metabolism , Thrombosis/virology , Trypsin/metabolism
6.
Cell Metab ; 33(8): 1577-1591.e7, 2021 08 03.
Article in English | MEDLINE | ID: covidwho-1240259

ABSTRACT

Recent clinical data have suggested a correlation between coronavirus disease 2019 (COVID-19) and diabetes. Here, we describe the detection of SARS-CoV-2 viral antigen in pancreatic beta cells in autopsy samples from individuals with COVID-19. Single-cell RNA sequencing and immunostaining from ex vivo infections confirmed that multiple types of pancreatic islet cells were susceptible to SARS-CoV-2, eliciting a cellular stress response and the induction of chemokines. Upon SARS-CoV-2 infection, beta cells showed a lower expression of insulin and a higher expression of alpha and acinar cell markers, including glucagon and trypsin1, respectively, suggesting cellular transdifferentiation. Trajectory analysis indicated that SARS-CoV-2 induced eIF2-pathway-mediated beta cell transdifferentiation, a phenotype that could be reversed with trans-integrated stress response inhibitor (trans-ISRIB). Altogether, this study demonstrates an example of SARS-CoV-2 infection causing cell fate change, which provides further insight into the pathomechanisms of COVID-19.


Subject(s)
COVID-19/virology , Cell Transdifferentiation , Insulin-Secreting Cells/virology , SARS-CoV-2/pathogenicity , Acetamides/pharmacology , Adolescent , Adult , Aged , Aged, 80 and over , Animals , COVID-19/mortality , Cell Transdifferentiation/drug effects , Chlorocebus aethiops , Cyclohexylamines/pharmacology , Cytokines/metabolism , Eukaryotic Initiation Factor-2/metabolism , Female , Glucagon , Host-Pathogen Interactions , Humans , Insulin/metabolism , Insulin-Secreting Cells/drug effects , Insulin-Secreting Cells/metabolism , Insulin-Secreting Cells/pathology , Male , Middle Aged , Phenotype , Signal Transduction , Tissue Culture Techniques , Trypsin/metabolism , Vero Cells , Young Adult
7.
Int J Biol Macromol ; 179: 601-609, 2021 May 15.
Article in English | MEDLINE | ID: covidwho-1131358

ABSTRACT

Proteinases with the (chymo)trypsin-like serine/cysteine fold comprise a large superfamily performing their function through the Acid - Base - Nucleophile catalytic triad. In our previous work (Denesyuk AI, Johnson MS, Salo-Ahen OMH, Uversky VN, Denessiouk K. Int J Biol Macromol. 2020;153:399-411), we described a universal three-dimensional (3D) structural motif, NBCZone, that contains eleven amino acids: dipeptide 42 T-43 T, pentapeptide 54 T-55 T-56 T-57 T(base)-58 T, tripeptide 195 T(nucleophile)-196 T-197 T and residue 213 T (T - numeration of amino acids in trypsin). The comparison of the NBCZones among the members of the (chymo)trypsin-like protease family suggested the existence of 15 distinct groups. Within each group, the NBCZones incorporate an identical set of conserved interactions and bonds. In the present work, the structural environment of the catalytic acid at the position 102 T and the fourth member of the "catalytic tetrad" at the position 214 T was analyzed in 169 3D structures of proteinases with the (chymo)trypsin-like serine/cysteine fold. We have identified a complete Structural Catalytic Core (SCC) consisting of two classes and four groups. The proteinases belonging to different classes and groups differ from each other by the nature of the interaction between their N- and C-terminal ß-barrels. Comparative analysis of the 3CLpro(s) from SARS-CoV-2 and SARS-CoV, used as an example, showed that the amino acids at positions 103 T and 179 T affect the nature of the interaction of the "catalytic acid" core (102 T-Core, N-terminal ß-barrel) with the "supplementary" core (S-Core, C-terminal ß-barrel), which ultimately results in the modulation of the enzymatic activity. The reported analysis represents an important standalone contribution to the analysis and systematization of the 3D structures of (chymo)trypsin-like serine/cysteine fold proteinases. The use of the developed approach for the comparison of 3D structures will allow, in the event of the appearance of new representatives of a given fold in the PDB, to quickly determine their structural homologues with the identification of possible differences.


Subject(s)
Cysteine Proteases/chemistry , Serine Proteases/chemistry , Amino Acid Sequence , Binding Sites , COVID-19/metabolism , Catalysis , Catalytic Domain , Cysteine Proteases/metabolism , Humans , Models, Molecular , SARS Virus/chemistry , SARS Virus/metabolism , SARS-CoV-2/chemistry , SARS-CoV-2/metabolism , Serine Endopeptidases/chemistry , Serine Endopeptidases/metabolism , Serine Proteases/metabolism , Trypsin/metabolism
8.
Emerg Microbes Infect ; 9(1): 457-468, 2020.
Article in English | MEDLINE | ID: covidwho-124862

ABSTRACT

Porcine deltacoronavirus (PDCoV) is a newly emerging threat to the global porcine industry. PDCoV has been successfully isolated using various medium additives including trypsin, and although we know it is important for viral replication, the mechanism has not been fully elucidated. Here, we systematically investigated the role of trypsin in PDCoV replication including cell entry, cell-to-cell membrane fusion and virus release. Using pseudovirus entry assays, we demonstrated that PDCoV entry is not trypsin dependent. Furthermore, unlike porcine epidemic diarrhea virus (PEDV), in which trypsin is important for the release of virus from infected cells, PDCoV release was not affected by trypsin. We also demonstrated that trypsin promotes PDCoV replication by enhancing cell-to-cell membrane fusion. Most importantly, our study illustrates two distinct spreading patterns from infected cells to uninfected cells during PDCoV transmission, and the role of trypsin in PDCoV replication in cells with different virus spreading types. Overall, these results clarify that trypsin promotes PDCoV replication by mediating cell-to-cell fusion transmission but is not crucial for viral entry. This knowledge can potentially contribute to improvement of virus production efficiency in culture, not only for vaccine preparation but also to develop antiviral treatments.


Subject(s)
Cell Fusion , Coronavirus/physiology , Membrane Fusion , Trypsin/metabolism , Animals , Cell Line , Humans , Swine , Virus Internalization , Virus Replication
9.
Nat Commun ; 11(1): 1620, 2020 03 27.
Article in English | MEDLINE | ID: covidwho-17830

ABSTRACT

Since 2002, beta coronaviruses (CoV) have caused three zoonotic outbreaks, SARS-CoV in 2002-2003, MERS-CoV in 2012, and the newly emerged SARS-CoV-2 in late 2019. However, little is currently known about the biology of SARS-CoV-2. Here, using SARS-CoV-2 S protein pseudovirus system, we confirm that human angiotensin converting enzyme 2 (hACE2) is the receptor for SARS-CoV-2, find that SARS-CoV-2 enters 293/hACE2 cells mainly through endocytosis, that PIKfyve, TPC2, and cathepsin L are critical for entry, and that SARS-CoV-2 S protein is less stable than SARS-CoV S. Polyclonal anti-SARS S1 antibodies T62 inhibit entry of SARS-CoV S but not SARS-CoV-2 S pseudovirions. Further studies using recovered SARS and COVID-19 patients' sera show limited cross-neutralization, suggesting that recovery from one infection might not protect against the other. Our results present potential targets for development of drugs and vaccines for SARS-CoV-2.


Subject(s)
Antibodies, Viral/immunology , Betacoronavirus/physiology , Broadly Neutralizing Antibodies/immunology , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , Virus Internalization , Angiotensin-Converting Enzyme 2 , Betacoronavirus/chemistry , Betacoronavirus/immunology , COVID-19 , Calcium Channels/metabolism , Cathepsin L/metabolism , Cathepsins/antagonists & inhibitors , Cathepsins/metabolism , Cell Fusion , Coronavirus Infections/immunology , Cross Reactions , Endocytosis , Giant Cells/physiology , HEK293 Cells , Humans , Neutralization Tests , Pandemics , Peptidyl-Dipeptidase A/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Pneumonia, Viral/immunology , Protein Domains , Protein Multimerization , Receptors, Virus/metabolism , SARS Virus/immunology , SARS-CoV-2 , Severe Acute Respiratory Syndrome/immunology , Spike Glycoprotein, Coronavirus/chemistry , Trypsin/metabolism
10.
Nat Microbiol ; 5(4): 562-569, 2020 04.
Article in English | MEDLINE | ID: covidwho-1966

ABSTRACT

Over the past 20 years, several coronaviruses have crossed the species barrier into humans, causing outbreaks of severe, and often fatal, respiratory illness. Since SARS-CoV was first identified in animal markets, global viromics projects have discovered thousands of coronavirus sequences in diverse animals and geographic regions. Unfortunately, there are few tools available to functionally test these viruses for their ability to infect humans, which has severely hampered efforts to predict the next zoonotic viral outbreak. Here, we developed an approach to rapidly screen lineage B betacoronaviruses, such as SARS-CoV and the recent SARS-CoV-2, for receptor usage and their ability to infect cell types from different species. We show that host protease processing during viral entry is a significant barrier for several lineage B viruses and that bypassing this barrier allows several lineage B viruses to enter human cells through an unknown receptor. We also demonstrate how different lineage B viruses can recombine to gain entry into human cells, and confirm that human ACE2 is the receptor for the recently emerging SARS-CoV-2.


Subject(s)
Betacoronavirus/physiology , Peptidyl-Dipeptidase A/metabolism , Receptors, Virus/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Virus Internalization , Angiotensin-Converting Enzyme 2 , Animals , Betacoronavirus/chemistry , Betacoronavirus/classification , CD13 Antigens/metabolism , COVID-19 , Cell Line , Coronavirus Infections/metabolism , Coronavirus Infections/virology , Dipeptidyl Peptidase 4/metabolism , Humans , Mutation , Pandemics , Peptidyl-Dipeptidase A/chemistry , Peptidyl-Dipeptidase A/genetics , Pneumonia, Viral/metabolism , Pneumonia, Viral/virology , Protein Domains , Receptors, Coronavirus , Receptors, Virus/chemistry , Receptors, Virus/genetics , Recombinant Fusion Proteins/metabolism , SARS Virus/chemistry , SARS Virus/physiology , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Trypsin/metabolism
11.
J Virol ; 94(5)2020 02 14.
Article in English | MEDLINE | ID: covidwho-908

ABSTRACT

Antibody-dependent enhancement (ADE) of viral entry has been a major concern for epidemiology, vaccine development, and antibody-based drug therapy. However, the molecular mechanism behind ADE is still elusive. Coronavirus spike protein mediates viral entry into cells by first binding to a receptor on the host cell surface and then fusing viral and host membranes. In this study, we investigated how a neutralizing monoclonal antibody (MAb), which targets the receptor-binding domain (RBD) of Middle East respiratory syndrome (MERS) coronavirus spike, mediates viral entry using pseudovirus entry and biochemical assays. Our results showed that MAb binds to the virus surface spike, allowing it to undergo conformational changes and become prone to proteolytic activation. Meanwhile, MAb binds to cell surface IgG Fc receptor, guiding viral entry through canonical viral-receptor-dependent pathways. Our data suggest that the antibody/Fc-receptor complex functionally mimics viral receptor in mediating viral entry. Moreover, we characterized MAb dosages in viral-receptor-dependent, Fc-receptor-dependent, and both-receptors-dependent viral entry pathways, delineating guidelines on MAb usages in treating viral infections. Our study reveals a novel molecular mechanism for antibody-enhanced viral entry and can guide future vaccination and antiviral strategies.IMPORTANCE Antibody-dependent enhancement (ADE) of viral entry has been observed for many viruses. It was shown that antibodies target one serotype of viruses but only subneutralize another, leading to ADE of the latter viruses. Here we identify a novel mechanism for ADE: a neutralizing antibody binds to the surface spike protein of coronaviruses like a viral receptor, triggers a conformational change of the spike, and mediates viral entry into IgG Fc receptor-expressing cells through canonical viral-receptor-dependent pathways. We further evaluated how antibody dosages impacted viral entry into cells expressing viral receptor, Fc receptor, or both receptors. This study reveals complex roles of antibodies in viral entry and can guide future vaccine design and antibody-based drug therapy.


Subject(s)
Antibodies, Viral/immunology , Antibody-Dependent Enhancement , Middle East Respiratory Syndrome Coronavirus/immunology , Middle East Respiratory Syndrome Coronavirus/physiology , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism , Virus Internalization , Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/metabolism , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/metabolism , Antibodies, Viral/metabolism , Cell Line , Dipeptidyl Peptidase 4/metabolism , Humans , Immunoglobulin Fab Fragments/immunology , Immunoglobulin Fab Fragments/metabolism , Middle East Respiratory Syndrome Coronavirus/pathogenicity , Peptide Hydrolases/metabolism , Proprotein Convertases/antagonists & inhibitors , Proprotein Convertases/metabolism , Protein Conformation , Protein Domains , Protein Multimerization , Receptors, Fc/metabolism , Receptors, IgG/immunology , Receptors, IgG/metabolism , Receptors, Virus/metabolism , Spike Glycoprotein, Coronavirus/chemistry , Trypsin/metabolism
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