COVID 19 – Eye Issues

2020 ◽  
Vol 5 (Special) ◽  
Keyword(s):  
Host Cell ◽  
Target Cell ◽  
Cell Receptor ◽  
Human Tissues ◽  
Type Ii ◽  
Cell Infection ◽  
Host Cell Receptor ◽  
Infected Cells ◽  
Cellular Entry

The coronavirus illness (COVID-19) is caused by a new recombinant SARS-CoV (SARS-CoV) virus (SARS-CoV-2). Target cell infection by SARS-CoV is mediated by the prickly protein of the coronavirus and host cell receptor, enzyme 2 converting angiotensin (ACE2) [3]. Similarly, a recent study suggests that cellular entry by SARS-CoV-2 is dependent on both ACE2 as well as type II transmembrane axial protease (TMPRSS2) [4]. This means that detection of ACE2 and PRSS2 expression in human tissues can predict potential infected cells and their respective effects in COVID-19 patients [1].

scholarly journals The Importance of Therapeutically Targeting the Binary Toxin from Clostridioides difficile

2021 ◽  
Vol 22 (6) ◽  
pp. 2926
Author(s):  
Dinendra L. Abeyawardhane ◽  
Raquel Godoy-Ruiz ◽  
Kaylin A. Adipietro ◽  
Kristen M. Varney ◽  
Richard R. Rustandi ◽  
...  
Keyword(s):  
Host Cell ◽  
The Elderly ◽  
Cell Receptor ◽  
Host Cells ◽  
Binary Toxin ◽  
Clostridioides Difficile ◽  
Host Cell Receptor ◽  
Oligomeric Assembly ◽  
Nosocomial Disease ◽  
Binary Toxins

Novel therapeutics are needed to treat pathologies associated with the Clostridioides difficile binary toxin (CDT), particularly when C. difficile infection (CDI) occurs in the elderly or in hospitalized patients having illnesses, in addition to CDI, such as cancer. While therapies are available to block toxicities associated with the large clostridial toxins (TcdA and TcdB) in this nosocomial disease, nothing is available yet to treat toxicities arising from strains of CDI having the binary toxin. Like other binary toxins, the active CDTa catalytic subunit of CDT is delivered into host cells together with an oligomeric assembly of CDTb subunits via host cell receptor-mediated endocytosis. Once CDT arrives in the host cell’s cytoplasm, CDTa catalyzes the ADP-ribosylation of G-actin leading to degradation of the cytoskeleton and rapid cell death. Although a detailed molecular mechanism for CDT entry and host cell toxicity is not yet fully established, structural and functional resemblances to other binary toxins are described. Additionally, unique conformational assemblies of individual CDT components are highlighted herein to refine our mechanistic understanding of this deadly toxin as is needed to develop effective new therapeutic strategies for treating some of the most hypervirulent and lethal strains of CDT-containing strains of CDI.

scholarly journals HIV-1 Envelope Conformation, Allostery, and Dynamics

Viruses ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 852
Author(s):  
Ashley Lauren Bennett ◽  
Rory Henderson
Keyword(s):  
Host Cell ◽  
Conformational Changes ◽  
Neutralizing Antibodies ◽  
Critical Role ◽  
Cell Receptor ◽  
Broadly Neutralizing Antibodies ◽  
Structural Mapping ◽  
Host Cell Receptor ◽  
Immunogen Design ◽  
Hiv 1

The HIV-1 envelope glycoprotein (Env) mediates host cell fusion and is the primary target for HIV-1 vaccine design. The Env undergoes a series of functionally important conformational rearrangements upon engagement of its host cell receptor, CD4. As the sole target for broadly neutralizing antibodies, our understanding of these transitions plays a critical role in vaccine immunogen design. Here, we review available experimental data interrogating the HIV-1 Env conformation and detail computational efforts aimed at delineating the series of conformational changes connecting these rearrangements. These studies have provided a structural mapping of prefusion closed, open, and transition intermediate structures, the allosteric elements controlling rearrangements, and state-to-state transition dynamics. The combination of these investigations and innovations in molecular modeling set the stage for advanced studies examining rearrangements at greater spatial and temporal resolution.

scholarly journals Ehrlichia chaffeensis and Its Invasin EtpE Block Reactive Oxygen Species Generation by Macrophages in a DNase X-Dependent Manner

mBio ◽  
2017 ◽  
Vol 8 (6) ◽  
Author(s):  
Omid Teymournejad ◽  
Mingqun Lin ◽  
Yasuko Rikihisa
Keyword(s):  
Host Cell ◽  
Cell Receptor ◽  
Ros Generation ◽  
Ehrlichia Chaffeensis ◽  
Biological Processes ◽  
Wild Type ◽  
New Approach ◽  
Host Cell Receptor ◽  
Life Threatening ◽  
Human Monocytic Ehrlichiosis

ABSTRACT The obligatory intracellular pathogen Ehrlichia chaffeensis lacks most genes that confer resistance to oxidative stress but can block reactive oxygen species (ROS) generation by host monocytes-macrophages. Bacterial and host molecules responsible for this inhibition have not been identified. To infect host cells, Ehrlichia uses the C terminus of its surface invasin, entry-triggering protein of Ehrlichia (EtpE; EtpE-C), which directly binds the mammalian cell surface receptor glycosylphosphatidylinositol-anchored protein DNase X. We investigated whether EtpE-C binding to DNase X blocks ROS production by mouse bone marrow-derived macrophages (BMDMs). On the basis of a luminol-dependent chemiluminescence assay, E. chaffeensis inhibited phorbol myristate acetate (PMA)-induced ROS generation by BMDMs from wild-type, but not DNase X−/−, mice. EtpE-C is critical for inhibition, as recombinant EtpE-C (rEtpE-C)-coated latex beads, but not recombinant N-terminal EtpE-coated or uncoated beads, inhibited PMA-induced ROS generation by BMDMs from wild-type mice. DNase X is required for this inhibition, as none of these beads inhibited PMA-induced ROS generation by BMDMs from DNase X−/− mice. Previous studies showed that E. chaffeensis does not block ROS generation in neutrophils, a cell type that is a potent ROS generator but is not infected by E. chaffeensis. Human and mouse peripheral blood neutrophils did not express DNase X. Our findings point to a unique survival mechanism of ROS-sensitive obligate intramonocytic bacteria that involves invasin EtpE binding to DNase X on the host cell surface. This is the first report of bacterial invasin having such a subversive activity on ROS generation. IMPORTANCE Ehrlichia chaffeensis preferentially infects monocytes-macrophages and causes a life-threatening emerging tick-transmitted infectious disease called human monocytic ehrlichiosis. Ehrlichial infection, and hence the disease, depends on the ability of this bacterium to avoid or overcome powerful microbicidal mechanisms of host monocytes-macrophages, one of which is the generation of ROS. Our findings reveal that an ehrlichial surface invasin, EtpE, not only triggers bacterial entry but also blocks ROS generation by host macrophages through its host cell receptor, DNase X. As ROS sensitivity is an Achilles’ heel of this group of pathogens, understanding the mechanism by which E. chaffeensis rapidly blocks ROS generation suggests a new approach for developing effective anti-infective measures. The discovery of a ROS-blocking pathway is also important, as modulation of ROS generation is important in a variety of ailments and biological processes. IMPORTANCE Ehrlichia chaffeensis preferentially infects monocytes-macrophages and causes a life-threatening emerging tick-transmitted infectious disease called human monocytic ehrlichiosis. Ehrlichial infection, and hence the disease, depends on the ability of this bacterium to avoid or overcome powerful microbicidal mechanisms of host monocytes-macrophages, one of which is the generation of ROS. Our findings reveal that an ehrlichial surface invasin, EtpE, not only triggers bacterial entry but also blocks ROS generation by host macrophages through its host cell receptor, DNase X. As ROS sensitivity is an Achilles’ heel of this group of pathogens, understanding the mechanism by which E. chaffeensis rapidly blocks ROS generation suggests a new approach for developing effective anti-infective measures. The discovery of a ROS-blocking pathway is also important, as modulation of ROS generation is important in a variety of ailments and biological processes.

Adherence of Legionella pneumophila to U-937 cells, guinea-pig alveolar macrophages, and MRC-5 cells by a novel, complement-independent binding mechanism

1994 ◽  
Vol 40 (10) ◽  
pp. 865-872 ◽  
Author(s):  
Frank C. Gibson III ◽  
Arthur O. Tzianabos ◽  
Frank G. Rodgers
Keyword(s):  
Monoclonal Antibodies ◽  
Guinea Pig ◽  
Host Cell ◽  
Alveolar Macrophages ◽  
Legionella Pneumophila ◽  
Cell Receptor ◽  
Host Cells ◽  
Order Kinetic ◽  
Complement Receptors ◽  
Host Cell Receptor

In the absence of serum, Legionella pneumophila demonstrated wash-resistant adherence to U-937 cells, primary guinea-pig alveolar macrophages, and MRC-5 cells. Neither complement nor antibody was required for binding. The dynamics of adherence following inoculation of L. pneumophila at increasing 10-fold multiplicities of infection to each of the three host cell types resulted in a first-order kinetic relationship of binding, indicative of one bacterial adhesin molecule recognized by one host cell receptor moiety. Host cell receptor saturation studies showed that depending on the cell type, 2–8% of the bacterial inoculum adhered to cells under these nonopsonic conditions. Preliminary adhesin and receptor characterization studies were preformed to define the chemical composition of the binding structures on both the organism and the three different host cell surfaces. The adherence phenomenon was investigated using competitive binding assays in the presence of putative adhesin analogs as well as following treatments modifying the microbial and host cell surface membranes. Attachment was evaluated both by viable bacterial cell colony counts and by indirect immunofluorescent assay. With the exception of aldehyde treatments, the various membrane-modifying regimes and the presence of the adhesin analogs were shown to have no effect on organism or host cell viability. Data suggested that the L. pneumophila adhesin responsible for opsonin-independent binding to these host cells was a protein structure with lectin-like properties. Furthermore, this protein would appear to be intimately associated with carbohydrate or lipid structures located on the bacterial outer membrane. The receptor moiety present on all host cells responsible for binding L. pneumophila had properties consistent with a carbohydrate or complex saccharide structure. To evaluate the role of complement receptors as the structures necessary for L. pneumophila infection of macrophages, a battery of monoclonal antibodies were used to block the complement receptor (CR) types 1 (CD35), CR3 (CD 18, CD11b), and CR4 (CD18, CD11c). Blocking studies with CR-specific monoclonal antibodies indicated that CR1 and the integrin receptors CR3 and CR4 were not involved in the opsonin-independent binding of L. pneumophila to macrophage-like cells.Key words: Legionella, opsonin-independent attachment, bacterial adherence, complement receptors, adhesion–receptor interactions.

scholarly journals Cryo-EM structure of the SARS coronavirus spike glycoprotein in complex with its host cell receptor ACE2

2018 ◽  
Vol 14 (8) ◽  
pp. e1007236 ◽  
Author(s):  
Wenfei Song ◽  
Miao Gui ◽  
Xinquan Wang ◽  
Ye Xiang
Keyword(s):  
Host Cell ◽  
Cell Receptor ◽  
Sars Coronavirus ◽  
Spike Glycoprotein ◽  
Host Cell Receptor

Avian Influenza H5-Containing Virus-Like Particles (VLPs): Host-Cell Receptor Specificity by STD NMR Spectroscopy

2008 ◽  
Vol 120 (10) ◽  
pp. 1936-1938 ◽  
Author(s):  
Thomas Haselhorst ◽  
Jean-Michel Garcia ◽  
Tasneem Islam ◽  
Jimmy C. C. Lai ◽  
Faith J. Rose ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Avian Influenza ◽  
Host Cell ◽  
Cell Receptor ◽  
Receptor Specificity ◽  
Virus Like Particles ◽  
Host Cell Receptor ◽  
Std Nmr

Avian Influenza H5-Containing Virus-Like Particles (VLPs): Host-Cell Receptor Specificity by STD NMR Spectroscopy

2008 ◽  
Vol 47 (10) ◽  
pp. 1910-1912 ◽  
Author(s):  
Thomas Haselhorst ◽  
Jean-Michel Garcia ◽  
Tasneem Islam ◽  
Jimmy C. C. Lai ◽  
Faith J. Rose ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Avian Influenza ◽  
Host Cell ◽  
Cell Receptor ◽  
Receptor Specificity ◽  
Virus Like Particles ◽  
Host Cell Receptor ◽  
Std Nmr

scholarly journals Identification of the Cellular Receptor of Clostridium spiroforme Toxin

2012 ◽  
Vol 80 (4) ◽  
pp. 1418-1423 ◽  
Author(s):  
Panagiotis Papatheodorou ◽  
Claudia Wilczek ◽  
Thilo Nölke ◽  
Gregor Guttenberg ◽  
Daniel Hornuss ◽  
...  
Keyword(s):  
Host Cell ◽  
Cell Receptor ◽  
Cell Surface Receptor ◽  
Target Cells ◽  
Content Type ◽  
Recombinant Production ◽  
Host Cell Receptor ◽  
Surface Receptor ◽  
Microscopic Studies ◽  
Host Cell Surface

ABSTRACTClostridium spiroformeproduces the binary actin-ADP-ribosylating toxin CST (C. spiroformetoxin), which has been proposed to be responsible for diarrhea, enterocolitis, and eventually death, especially in rabbits. Here we report on the recombinant production of the enzyme component (CSTa) and the binding component (CSTb) ofC. spiroformetoxin inBacillus megaterium. By using the recombinant toxin components, we show that CST enters target cells via the lipolysis-stimulated lipoprotein receptor (LSR), which has been recently identified as the host cell receptor of the binary toxinsClostridium difficiletransferase (CDT) andClostridium perfringensiota toxin. Microscopic studies revealed that CST, but not the relatedClostridium botulinumC2 toxin, colocalized with LSR during toxin uptake and traffic to endosomal compartments. Our findings indicate that CST shares LSR withC. difficileCDT andC. perfringensiota toxin as a host cell surface receptor.

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