scholarly journals An intra-cytoplasmic route for SARS-CoV-2 transmission unveiled by Helium-ion microscopy

2021 ◽  
Author(s):  
Antonio Merolli ◽  
Leila Kasaei ◽  
Santhamani Ramsamy ◽  
Afsal Kolloli ◽  
Ranjeet Kumar ◽  
...  
Keyword(s):  
Large Scale ◽  
Immune Surveillance ◽  
Microscopy Study ◽  
Host Cells ◽  
Tunneling Nanotubes ◽  
Molecular Events ◽  
Helium Ion ◽  
Docking Mechanism ◽  
Infected Cells ◽  
Ion Microscopy

Abstract SARS-CoV-2 virions enter the host cells by docking their spike glycoproteins to the membrane-bound Angiotensin Converting Enzyme 2. After intracellular assembly, the newly formed virions are released from the infected cells to propagate the infection, using the extra-cytoplasmic ACE2 docking mechanism. However, the molecular events underpinning SARS-CoV-2 transmission between host cells are not fully understood. Here, we report the findings of a scanning Helium-ion microscopy study performed on Vero E6 cells infected with mNeonGreen-expressing SARS-CoV-2. Our data reveal, with unprecedented resolution, the presence of: 1)-long tunneling nanotubes that connect two or more host cells over submillimeter distances; 2)-large scale multiple cell fusion events (syncytia); and 3)-abundant extracellular vesicles of various sizes. Taken together, these ultrastructural features describe a novel intra-cytoplasmic connection among SARS-CoV-2 infected cells that may act as an alternative route of viral transmission, disengaged from the well-known extra-cytoplasmic ACE2 docking mechanism. Our findings may explain the elusiveness of SARS-CoV-2 to survive from the immune surveillance of the infected host.

scholarly journals Acoustic attenuation spectroscopy and helium ion microscopy study of rehydration of dairy powder

2020 ◽  
Vol 600 ◽  
pp. 124795 ◽  
Author(s):  
Zachary J. Glover ◽  
Mathew J. Francis ◽  
Jacek Fiutowski ◽  
Qinxin Sun ◽  
Qinya Yu ◽  
...  
Keyword(s):  
Microscopy Study ◽  
Acoustic Attenuation ◽  
Helium Ion ◽  
Ion Microscopy

scholarly journals Trogocytosis-associated cell to cell spread of intracellular bacterial pathogens

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Shaun Steele ◽  
Lauren Radlinski ◽  
Sharon Taft-Benz ◽  
Jason Brunton ◽  
Thomas H Kawula
Keyword(s):  
Immune Cell ◽  
Bacterial Pathogens ◽  
Immune Surveillance ◽  
Cell Types ◽  
Antimicrobial Activities ◽  
Host Cells ◽  
Phagocytic Cells ◽  
Microbial Infections ◽  
Infected Cells

Macrophages are myeloid-derived phagocytic cells and one of the first immune cell types to respond to microbial infections. However, a number of bacterial pathogens are resistant to the antimicrobial activities of macrophages and can grow within these cells. Macrophages have other immune surveillance roles including the acquisition of cytosolic components from multiple types of cells. We hypothesized that intracellular pathogens that can replicate within macrophages could also exploit cytosolic transfer to facilitate bacterial spread. We found that viable Francisella tularensis, as well as Salmonella enterica bacteria transferred from infected cells to uninfected macrophages along with other cytosolic material through a transient, contact dependent mechanism. Bacterial transfer occurred when the host cells exchanged plasma membrane proteins and cytosol via a trogocytosis related process leaving both donor and recipient cells intact and viable. Trogocytosis was strongly associated with infection in mice, suggesting that direct bacterial transfer occurs by this process in vivo.

scholarly journals The EspD Protein of EnterohemorrhagicEscherichia coli Is Required for the Formation of Bacterial Surface Appendages and Is Incorporated in the Cytoplasmic Membranes of Target Cells

1999 ◽  
Vol 67 (9) ◽  
pp. 4834-4842 ◽  
Author(s):  
Andreas U. Kresse ◽  
Manfred Rohde ◽  
Carlos A. Guzmán
Keyword(s):  
Shiga Toxin ◽  
Host Cells ◽  
Target Cells ◽  
Wild Type ◽  
Bacterial Surface ◽  
E Coli ◽  
Molecular Events ◽  
Cytoplasmic Membranes ◽  
Infected Cells

ABSTRACT The formation of EspA-containing surface appendages in pathogenicEscherichia coli strains, both enteropathogenic E. coli (EPEC) and Shiga toxin-producing E. colistrains, is essential for critical events in the infective process, e.g., localized bacterial adherence to host cells with formation of microcolonies and induction of attaching and effacing lesions. It has been reported that EPEC mutants deficient in the production of EspD, which is encoded by the esp operon, are unable to accumulate actin underneath adherent bacteria but exhibit an attachment similar to that of the wild type. Here, we report the construction and characterization of an in-frame espD deletion mutant of the enterohemorrhagic E. coli (EHEC) strain EDL933. In contrast to what was observed in EPEC mutants, the EDL933 espDmutant not only lacked the capacity to accumulate actin but also exhibited an impaired attachment to HeLa cells. The synthesis of the EspD protein was also essential for the formation of EspA-containing filaments. Finally, localization studies demonstrated that the EspD protein is transferred to the cytoplasm and integrated into the cytoplasmic membranes of infected cells. These results help to elucidate the underlying molecular events in infections caused by EHEC.

Electron microscopy study of reactively sputter-deposited Ti/N films on silicon

1992 ◽  
Vol 50 (2) ◽  
pp. 1362-1363
Author(s):  
V. C. Kannan ◽  
A. K. Singh ◽  
R. B. Irwin ◽  
S. Chittipeddi ◽  
F. D. Nkansah ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Large Scale ◽  
Hexagonal Phase ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Process Conditions ◽  
Tin Films ◽  
Wide Range ◽  
Fcc Phase ◽  
Circuits Vlsi

Titanium nitride (TiN) films have historically been used as diffusion barrier between silicon and aluminum, as an adhesion layer for tungsten deposition and as an interconnect material etc. Recently, the role of TiN films as contact barriers in very large scale silicon integrated circuits (VLSI) has been extensively studied. TiN films have resistivities on the order of 20μ Ω-cm which is much lower than that of titanium (nearly 66μ Ω-cm). Deposited TiN films show resistivities which vary from 20 to 100μ Ω-cm depending upon the type of deposition and process conditions. TiNx is known to have a NaCl type crystal structure for a wide range of compositions. Change in color from metallic luster to gold reflects the stabilization of the TiNx (FCC) phase over the close packed Ti(N) hexagonal phase. It was found that TiN (1:1) ideal composition with the FCC (NaCl-type) structure gives the best electrical property.

HIMaging the kidney: High resolution helium ion microscopy

2014 ◽  
pp. 32-35
Author(s):  
Teodor Paunescu ◽  
Sylvie Breton ◽  
Dennis Brown
Keyword(s):  
High Resolution ◽  
Helium Ion ◽  
Ion Microscopy

Large-Scale Focused Helium Ion Beam Lithography

2021 ◽  
Vol 31 (5) ◽  
pp. 1-4
Author(s):  
Jay C. LeFebvre ◽  
Shane A. Cybart
Keyword(s):  
Large Scale ◽  
Ion Beam ◽  
Ion Beam Lithography ◽  
Helium Ion

scholarly journals Helicobacter pylori Outer Membrane Vesicles and Extracellular Vesicles from Helicobacter pylori-Infected Cells in Gastric Disease Development

2021 ◽  
Vol 22 (9) ◽  
pp. 4823
Author(s):  
María Fernanda González ◽  
Paula Díaz ◽  
Alejandra Sandoval-Bórquez ◽  
Daniela Herrera ◽  
Andrew F. G. Quest
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
Outer Membrane ◽  
Extracellular Vesicles ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Gastric Epithelium ◽  
Infected Cells ◽  
H Pylori

Extracellular vesicles (EVs) are cell-derived vesicles important in intercellular communication that play an essential role in host-pathogen interactions, spreading pathogen-derived as well as host-derived molecules during infection. Pathogens can induce changes in the composition of EVs derived from the infected cells and use them to manipulate their microenvironment and, for instance, modulate innate and adaptive inflammatory immune responses, both in a stimulatory or suppressive manner. Gastric cancer is one of the leading causes of cancer-related deaths worldwide and infection with Helicobacter pylori (H. pylori) is considered the main risk factor for developing this disease, which is characterized by a strong inflammatory component. EVs released by host cells infected with H. pylori contribute significantly to inflammation, and in doing so promote the development of disease. Additionally, H. pylori liberates vesicles, called outer membrane vesicles (H. pylori-OMVs), which contribute to atrophia and cell transformation in the gastric epithelium. In this review, the participation of both EVs from cells infected with H. pylori and H. pylori-OMVs associated with the development of gastric cancer will be discussed. By deciphering which functions of these external vesicles during H. pylori infection benefit the host or the pathogen, novel treatment strategies may become available to prevent disease.

scholarly journals “Limiting access to iron decreases infection of Atlantic salmon SHK-1 cells with bacterium Piscirickettsia salmonis”

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Rodrigo Díaz ◽  
José Troncoso ◽  
Eva Jakob ◽  
Stanko Skugor
Keyword(s):  
Gene Expression ◽  
Iron Deficiency ◽  
Atlantic Salmon ◽  
Bacterial Load ◽  
Host Cells ◽  
Immune Gene ◽  
Immune Signaling ◽  
Immune Effector ◽  
Infected Cells ◽  
Piscirickettsia Salmonis

Abstract Background Vertebrate hosts limit the availability of iron to microbial pathogens in order to nutritionally starve the invaders. The impact of iron deficiency induced by the iron chelator deferoxamine mesylate (DFO) was investigated in Atlantic salmon SHK-1 cells infected with the facultative intracellular bacterium Piscirickettsia salmonis. Results Effects of the DFO treatment and P. salmonis on SHK-1 cells were gaged by assessing cytopathic effects, bacterial load and activity, and gene expression profiles of eight immune biomarkers at 4- and 7-days post infection (dpi) in the control group, groups receiving single treatments (DFO or P. salmonis) and their combination. The chelator appears to be well-tolerated by host cells, while it had a negative impact on the number of bacterial cells and associated cytotoxicity. DFO alone had minor effects on gene expression of SHK-1 cells, including an early activation of IL-1β at 4 dpi. In contrast to few moderate changes induced by single treatments (either infection or chelator), most genes had highest upregulation in the infected groups receiving DFO. The mildest induction of hepcidin-1 (antimicrobial peptide precursor and regulator of iron homeostasis) was observed in cells exposed to DFO alone, followed by P. salmonis infected cells while the addition of DFO to infected cells further increased the mRNA abundance of this gene. Transcripts encoding TNF-α (immune signaling) and iNOS (immune effector) showed sustained increase at both time points in this group while cathelicidin-1 (immune effector) and IL-8 (immune signaling) were upregulated at 7 dpi. The stimulation of protective gene responses seen in infected cultures supplemented with DFO coincided with the reduction of bacterial load and activity (judged by the expression of P. salmonis 16S rRNA), and damage to cultured host cells. Conclusion The absence of immune gene activation under normal iron conditions suggests modulation of host responses by P. salmonis. The negative effect of iron deficiency on bacteria likely allowed host cells to respond in a more protective manner to the infection, further decreasing its progression. Presented findings encourage in vivo exploration of iron chelators as a promising strategy against piscirickettsiosis.

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