scholarly journals Structural changes in the membrane of vero cells infected with a paramyxovirus.

1975 ◽  
Vol 67 (3) ◽  
pp. 551-565 ◽  
Author(s):  
M Dubois-Dalcq ◽  
T S Reese
Keyword(s):  
Cell Membrane ◽  
Measles Virus ◽  
Structural Changes ◽  
Vero Cells ◽  
Small Particles ◽  
Freeze Fracturing ◽  
Viral Antigens ◽  
Viral Budding ◽  
Membrane Surfaces ◽  
Viral Maturation

Vero cells productively infected with the Halle strain of measles virus have been studied by means of surface replication, freeze-fracturing, and surface labeling with horseradish peroxidase-measles antibody conjugate in order to examine changes in the structure of the cell membrane during viral maturation. Early in infection, the surfaces of infected cells are embossed by scattered groups of twisted strands, and diffuse patches of label for viral antigens cover regions marked by these strands. At later stages, when numerous nucleocapsids become aligned under the plasmalemmal strands, the strands increase in number and width and become more convoluted. At this stage, label for viral antigens on the surface of the cell membrane is organized into stripes lying on the crests of strands. Finally, regions of the membrane displaying twisted strands protrude to form ridges or bulges, and the freeze-fractured membrane surrounding these protrusions is characterized by an abundance of particles small than those found on the rest of the cell membrane. The fractured membranes of viral buds are continuous sheets of these small particles, and the spacing between both nucleocapsids and stripes of surface antigen in buds is less than in the surrounding cell membrane. Detached virus is covered with a continuous layer of viral antigen, has unusually large but no small particles on its membrane surfaces exposed by freeze-fracturing, and no longer has nucleocapsids aligned under its surface. Thus, surface antigens, membrane particles, and nucleocapsids attached to the cell membrane are mobile within the plane of the membrane during viral maturation. All three move simutaneously in preparation for viral budding.

Stereo Electron Microscopy Applied to High Resolution Freeze-Etch Replicas

1970 ◽  
Vol 28 ◽  
pp. 306-307
Author(s):  
L. Andrew Staehelin
Keyword(s):  
Electron Microscopy ◽  
Plastic Deformation ◽  
High Resolution ◽  
Smooth Surfaces ◽  
Small Particles ◽  
Membrane Surfaces ◽  
Wide Acceptance ◽  
New Information ◽  
Number Of Particles ◽  
Small Holes

Freeze-etched membranes usually appear as relatively smooth surfaces covered with numerous small particles and a few small holes (Fig. 1). In 1966 Branton (1“) suggested that these surfaces represent split inner mem¬brane faces and not true external membrane surfaces. His theory has now gained wide acceptance partly due to new information obtained from double replicas of freeze-cleaved specimens (2,3) and from freeze-etch experi¬ments with surface labeled membranes (4). While theses studies have fur¬ther substantiated the basic idea of membrane splitting and have shown clearly which membrane faces are complementary to each other, they have left the question open, why the replicated membrane faces usually exhibit con¬siderably fewer holes than particles. According to Branton's theory the number of holes should on the average equal the number of particles. The absence of these holes can be explained in either of two ways: a) it is possible that no holes are formed during the cleaving process e.g. due to plastic deformation (5); b) holes may arise during the cleaving process but remain undetected because of inadequate replication and microscope techniques.

scholarly journals Heparin Inhibits Cellular Invasion by SARS-CoV-2: Structural Dependence of the Interaction of the Spike S1 Receptor-Binding Domain with Heparin

2020 ◽  
Vol 120 (12) ◽  
pp. 1700-1715
Author(s):  
Courtney J. Mycroft-West ◽  
Dunhao Su ◽  
Isabel Pagani ◽  
Timothy R. Rudd ◽  
Stefano Elli ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Structural Changes ◽  
Rapid Development ◽  
Antiviral Agents ◽  
Vero Cells ◽  
Binding Domain ◽  
Microbial Pathogens ◽  
Minimum Size ◽  
Structural Basis ◽  
Receptor Binding Domain

AbstractThe dependence of development and homeostasis in animals on the interaction of hundreds of extracellular regulatory proteins with the peri- and extracellular glycosaminoglycan heparan sulfate (HS) is exploited by many microbial pathogens as a means of adherence and invasion. Heparin, a widely used anticoagulant drug, is structurally similar to HS and is a common experimental proxy. Exogenous heparin prevents infection by a range of viruses, including S-associated coronavirus isolate HSR1. Here, we show that heparin inhibits severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) invasion of Vero cells by up to 80% at doses achievable through prophylaxis and, particularly relevant, within the range deliverable by nebulisation. Surface plasmon resonance and circular dichroism spectroscopy demonstrate that heparin and enoxaparin, a low-molecular-weight heparin which is a clinical anticoagulant, bind and induce a conformational change in the spike (S1) protein receptor-binding domain (S1 RBD) of SARS-CoV-2. A library of heparin derivatives and size-defined fragments were used to probe the structural basis of this interaction. Binding to the RBD is more strongly dependent on the presence of 2-O or 6-O sulfate groups than on N-sulfation and a hexasaccharide is the minimum size required for secondary structural changes to be induced in the RBD. It is likely that inhibition of viral infection arises from an overlap between the binding sites of heparin/HS on S1 RBD and that of the angiotensin-converting enzyme 2. The results suggest a route for the rapid development of a first-line therapeutic by repurposing heparin and its derivatives as antiviral agents against SARS-CoV-2 and other members of the Coronaviridae.

A Study of the Measles Virus-Induced Proteins Incorporated into the Cell Membrane

Intervirology ◽  
1979 ◽  
Vol 11 (5) ◽  
pp. 275-281 ◽  
Author(s):  
Fabian Wild ◽  
Tim Greenland
Keyword(s):  
Cell Membrane ◽  
Measles Virus ◽  
Induced Proteins

scholarly journals Cell Membrane-Associated Measles Virus Components Inhibit Antigen Processing

Virology ◽  
2001 ◽  
Vol 279 (2) ◽  
pp. 422-428 ◽  
Author(s):  
Jane Marttila ◽  
Ari Hinkkanen ◽  
Thedi Ziegler ◽  
Raija Vainionpää ◽  
Aimo Salmi ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Measles Virus ◽  
Antigen Processing

Bilayer stabilizing peptides and the inhibition of viral infection: antimeasles activity of carbobenzoxy-Ser-Leu-amide

1987 ◽  
Vol 7 (9) ◽  
pp. 745-749 ◽  
Author(s):  
Richard M. Epand ◽  
Thomas J. Lobl ◽  
H. E. Renis
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Measles Virus ◽  
Cytopathic Effect ◽  
Hexagonal Phase ◽  
Vero Cells ◽  
Time Parameter ◽  
Scanning Calorimetry ◽  
Hplc Retention Time

A number of carbobenzoxy-dipeptide-amides raise the bilayer to hexagonal phase transition temperature of dielaidoylphosphatidylethanolamine (stabilizes the bilayer). The potency of the peptides in stabilizing the bilayer phase is Z-Tyr-Leu-NH2>Z-Gly-Phe-NH2>Z-Ser-Leu-NH2>Z-Gly-Leu-NH2>Z-Gly-Gly-NH2. A linear correlation was found between the respective HPLC retention time parameter k′ for the peptide and the slope of the bilayer stabilization curve determined with model membranes by differential scanning calorimetry. One dipeptide, Z-Ser-Leu-NH2, reduces measles virus cytopathic effect (CPE) in Vero cells. The mechanism by which this peptide reduces the CPE is not known, although some peptides which raise the bilayer to hexagonal phase transition temperature of phospholipids inhibit membrane fusion.

Short-stalk isoforms of CADM1 and CADM2 trigger neuropathogenic measles virus-mediated membrane fusion by interacting with the viral hemagglutinin

2021 ◽  
Author(s):  
Ryuichi Takemoto ◽  
Tateki Suzuki ◽  
Takao Hashiguchi ◽  
Yusuke Yanagi ◽  
Yuta Shirogane
Keyword(s):  
Cell Membrane ◽  
Membrane Fusion ◽  
Measles Virus ◽  
Subacute Sclerosing Panencephalitis ◽  
Febrile Illness ◽  
Host Factors ◽  
F Protein ◽  
Short Stalk ◽  
Head Domain ◽  
H Protein

Measles virus (MeV), an enveloped RNA virus in the family Paramyxoviridae , usually causes acute febrile illness with skin rash, but in rare cases persists in the brain, causing a progressive neurological disorder, subacute sclerosing panencephalitis (SSPE). MeV bears two envelope glycoproteins, the hemagglutinin (H) and fusion (F) proteins. The H protein possesses a head domain that initially mediates receptor binding and a stalk domain that subsequently transmits the fusion-triggering signal to the F protein. We have recently shown that cell adhesion molecule 1 (CADM1, also known as IGSF4A, Necl-2, SynCAM1) and CADM2 (also known as IGSF4D, Necl-3, SynCAM2) are host factors enabling cell-cell membrane fusion mediated by hyperfusogenic F proteins of neuropathogenic MeVs as well as MeV spread between neurons lacking the known receptors. CADM1 and CADM2 interact in cis with the H protein on the same cell membrane, triggering hyperfusogenic F protein-mediated membrane fusion. Multiple isoforms of CADM1 and CADM2 containing various lengths of their stalk regions are generated by alternative splicing. Here we show that only short-stalk isoforms of CADM1 and CADM2 predominantly expressed in the brain induce hyperfusogenic F protein-mediated membrane fusion. While the known receptors interact in trans with the H protein through its head domain, these isoforms can interact in cis even with the H protein lacking the head domain and trigger membrane fusion, presumably through its stalk domain. Thus, our results unveil a new mechanism of viral fusion triggering by host factors. Importance Measles, an acute febrile illness with skin rash, is still an important cause of childhood morbidity and mortality worldwide. Measles virus (MeV), the causative agent of measles, may also cause a progressive neurological disorder, subacute sclerosing panencephalitis (SSPE), several years after acute infection. The disease is fatal, and no effective therapy is available. Recently, we have reported that cell adhesion molecule 1 (CADM1) and CADM2 are host factors enabling MeV cell-to-cell spread in neurons. These molecules interact in cis with the MeV attachment protein on the same cell membrane, triggering the fusion protein and causing membrane fusion. CADM1 and CADM2 are known to exist in multiple splice isoforms. In this study, we report that their short-stalk isoforms can induce membrane fusion by interacting in cis with the viral attachment protein independently of its receptor-binding head domain. This finding may have important implications for cis -acting fusion triggering by host factors.

scholarly journals Deformation Measurements of Neuronal Excitability Using Incoherent Holography Lattice Light-Sheet Microscopy (IHLLS)

Photonics ◽  
2021 ◽  
Vol 8 (9) ◽  
pp. 383
Author(s):  
Mariana Potcoava ◽  
Jonathan Art ◽  
Simon Alford ◽  
Christopher Mann
Keyword(s):  
Cell Membrane ◽  
Structural Changes ◽  
Neuronal Excitability ◽  
Light Sheet ◽  
Phase Imaging ◽  
Excitable Cells ◽  
Full Field ◽  
Cellular Processes ◽  
Light Sheet Microscopy ◽  
Fluorescent Markers

Stimuli to excitable cells and various cellular processes can cause cell surface deformations; for example, when excitable cell membrane potentials are altered during action potentials. However, these cellular changes may be at or below the diffraction limit (in dendrites the structures measured are as small as 1 µm), and imaging by traditional methods is challenging. Using dual lenses incoherent holography lattice light-sheet (IHLLS-2L) detection with holographic phase imaging of selective fluorescent markers, we can extract the full-field cellular morphology or structural changes of the object’s phase in response to external stimulus. This approach will open many new possibilities in imaging neuronal activity and, overall, in light sheet imaging. In this paper, we present IHLLS-2L as a well-suited technique for quantifying cell membrane deformation in neurons without the actuation of a sample stage or detection microscope objective.

scholarly journals Volume and surface changes in vero cell and its nucleus after infection with measles virus: a stereological study

2011 ◽  
Vol 2 (1) ◽  
pp. 18
Author(s):  
Ali Noorafshan ◽  
Mohammad Motamedifar ◽  
Saied Karbalay-Doust
Keyword(s):  
Vero Cell ◽  
Post Infection ◽  
Measles Virus ◽  
Plaque Assay ◽  
Vero Cells ◽  
Uninfected Control ◽  
Mean Cell Volume ◽  
Significant Difference ◽  
Infected Cells ◽  
The Mean

Measles virus has no or indistinctive cytopathic effects (CPE) in cell couture system. Employment of some detecting methods like plaque assay or stereologic experiments, as a method of detecting of viral infection in the cells would be applicable. The aim of this study was investigating the early changes in quantitative parameters of measles virus infected Vero cells. Stereological methods using invariator, were applied for the first time to estimate cell and nucleus volume and cell surface of the infected Vero cell line with the measles virus.This method can be applied on other cultured cells.Vero cells grown in tissue culture plates for 48 hours at 36˚C were infected with 100TCID50 of AiK strain of measles virus. Volume and surface of the infected Vero cells were studied at 4, 9 and 25 hours post infection along with uninfected control cells. The mean cell volume and surface of the cells infected with measles virus, increased ~87% and ~50%, respectively, 4 hours post-infection, as compared with the uninfected control. The nuclei did not show any differences. The mean parameters of infected cells in other time intervals showed no significant difference comparing with the control cells. Although there are other specific methods, stereology may be used as an integrated protocol to detect cytophatic changes of the measles virus infected cells early in the permissive cell culture system.

scholarly journals Specificity of Morbillivirus Hemagglutinins to Recognize SLAM of Different Species

Viruses ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 761 ◽  
Author(s):  
Hideo Fukuhara ◽  
Yuri Ito ◽  
Miyuki Sako ◽  
Mizuho Kajikawa ◽  
Koki Yoshida ◽  
...  
Keyword(s):  
Measles Virus ◽  
Canine Distemper Virus ◽  
Complex Structure ◽  
Lymphocyte Activation ◽  
Vero Cells ◽  
Binding Potential ◽  
Tissue Tropism ◽  
Receptor Recognition ◽  
Mutagenesis Study ◽  
H Protein

Measles virus (MV) and canine distemper virus (CDV) are highly contagious and deadly, forming part of the morbillivirus genus. The receptor recognition by morbillivirus hemagglutinin (H) is important for determining tissue tropism and host range. Recent reports largely urge caution as regards to the potential expansion of host specificities of morbilliviruses. Nonetheless, the receptor-binding potential in different species of morbillivirus H proteins is largely unknown. Herein, we show that the CDV-H protein binds to the dog signaling lymphocyte activation molecule (SLAM), but not to the human, tamarin, or mouse SLAM. In contrast, MV-H can bind to human, tamarin and dog SLAM, but not to that of mice. Notably, MV binding to dog SLAM showed a lower affinity and faster kinetics than that of human SLAM, and MV exhibits a similar entry activity in dog SLAM- and human SLAM-expressing Vero cells. The mutagenesis study using a fusion assay, based on the MV-H–SLAM complex structure, revealed differences in tolerance for the receptor specificity between MV-H and CDV-H. These results provide insights into H-SLAM specificity related to potential host expansion.

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