Faculty Opinions recommendation of Vaccinia virus penetration requires cholesterol and results in specific viral envelope proteins associated with lipid rafts.

2005 ◽  
Author(s):  
Grant McFadden
Keyword(s):  
Vaccinia Virus ◽  
Lipid Rafts ◽  
Envelope Proteins ◽  
Viral Envelope ◽  
Viral Envelope Proteins

scholarly journals Vaccinia Virus Penetration Requires Cholesterol and Results in Specific Viral Envelope Proteins Associated with Lipid Rafts

2005 ◽  
Vol 79 (3) ◽  
pp. 1623-1634 ◽  
Author(s):  
Che-Sheng Chung ◽  
Cheng-Yen Huang ◽  
Wen Chang
Keyword(s):  
Plasma Membrane ◽  
Virus Infection ◽  
Vaccinia Virus ◽  
Lipid Rafts ◽  
Lipid Raft ◽  
Mammalian Cells ◽  
Membrane Lipid ◽  
Envelope Proteins ◽  
Viral Envelope ◽  
Viral Envelope Proteins

ABSTRACT Vaccinia virus infects a wide variety of mammalian cells from different hosts, but the mechanism of virus entry is not clearly defined. The mature intracellular vaccinia virus contains several envelope proteins mediating virion adsorption to cell surface glycosaminoglycans; however, it is not known how the bound virions initiate virion penetration into cells. For this study, we investigated the importance of plasma membrane lipid rafts in the mature intracellular vaccinia virus infection process by using biochemical and fluorescence imaging techniques. A raft-disrupting drug, methyl-β-cyclodextrin, inhibited vaccinia virus uncoating without affecting virion attachment, indicating that cholesterol-containing lipid rafts are essential for virion penetration into mammalian cells. To provide direct evidence of a virus and lipid raft association, we isolated detergent-insoluble glycolipid-enriched membranes from cells immediately after virus infection and demonstrated that several viral envelope proteins, A14, A17L, and D8L, were present in the cell membrane lipid raft fractions, whereas the envelope H3L protein was not. Such an association did not occur after virions attached to cells at 4°C and was only observed when virion penetration occurred at 37°C. Immunofluorescence microscopy also revealed that cell surface staining of viral envelope proteins was colocalized with GM1, a lipid raft marker on the plasma membrane, consistent with biochemical analyses. Finally, mutant viruses lacking the H3L, D8L, or A27L protein remained associated with lipid rafts, indicating that the initial attachment of vaccinia virions through glycosaminoglycans is not required for lipid raft formation.

scholarly journals Role of Receptor-Mediated Endocytosis in the Formation of Vaccinia Virus Extracellular Enveloped Particles

2005 ◽  
Vol 79 (7) ◽  
pp. 4080-4089 ◽  
Author(s):  
Matloob Husain ◽  
Bernard Moss
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Vaccinia Virus ◽  
Adaptor Protein ◽  
Viral Proteins ◽  
Envelope Proteins ◽  
Viral Envelope ◽  
Coated Pits ◽  
Receptor Mediated Endocytosis ◽  
Viral Envelope Proteins

ABSTRACT Infectious intracellular mature vaccinia virus particles are wrapped by cisternae, which may arise from trans-Golgi or early endosomal membranes, and are transported along microtubules to the plasma membrane where exocytosis occurs. We used EH21, a dominant-negative form of Eps15 that is an essential component of clathrin-coated pits, to investigate the extent and importance of endocytosis of viral envelope proteins from the cell surface. Several recombinant vaccinia viruses that inducibly or constitutively express an enhanced green fluorescent protein (GFP)-EH21 fusion protein were constructed. Expression of GFP-EH21 blocked uptake of transferrin, a marker for clathrin-mediated endocytosis, as well as association of adaptor protein-2 with clathrin-coated pits. When GFP-EH21 was expressed, there were increased amounts of viral envelope proteins, including A33, A36, B5, and F13, in the plasma membrane, and their internalization was inhibited. Wrapping of virions appeared to be qualitatively unaffected as judged by electron microscopy, a finding consistent with a primary trans-Golgi origin of the cisternae. However, GFP-EH21 expression caused a 50% reduction in released enveloped virions, decreased formation of satellite plaques, and delayed virus spread, indicating an important role for receptor-mediated endocytosis. Due to dynamic interconnection between endocytic and exocytic pathways, viral proteins recovered from the plasma membrane could be used by trans-Golgi or endosomal cisternae to form new viral envelopes. Adherence of enveloped virions to unrecycled viral proteins on the cell surface may also contribute to decreased virus release in the presence of GFP-EH21. In addition to a salvage function, the retrieval of viral proteins from the cell surface may reduce immune recognition.

scholarly journals Mammalian cell surface display for monoclonal antibody-based FACS selection of viral envelope proteins

mAbs ◽  
2017 ◽  
Vol 9 (7) ◽  
pp. 1052-1064 ◽  
Author(s):  
Tim-Henrik Bruun ◽  
Veronika Grassmann ◽  
Benjamin Zimmer ◽  
Benedikt Asbach ◽  
David Peterhoff ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Cell Surface ◽  
Mammalian Cell ◽  
Surface Display ◽  
Cell Surface Display ◽  
Envelope Proteins ◽  
Viral Envelope ◽  
Selection Of ◽  
Viral Envelope Proteins

scholarly journals Cellular actin-binding ezrin-radixin-moesin (ERM) family proteins are incorporated into the rabies virion and closely associated with viral envelope proteins in the cell

Virology ◽  
1995 ◽  
Vol 206 (1) ◽  
pp. 485-494 ◽  
Author(s):  
Junji Sagara ◽  
Sachiko Tsukita ◽  
Shigenobu Yonemura ◽  
Shoichiro Tsukita ◽  
Akihiko Kawai
Keyword(s):  
Envelope Proteins ◽  
Viral Envelope ◽  
Actin Binding ◽  
Viral Envelope Proteins

scholarly journals Identification of H209 as Essential for pH 8-Triggered Receptor-Independent Syncytium Formation by S Protein of Mouse Hepatitis Virus A59

2018 ◽  
Vol 92 (11) ◽  
Author(s):  
Pei Li ◽  
Yiwei Shan ◽  
Wangliang Zheng ◽  
Xiuyuan Ou ◽  
Dan Mi ◽  
...  
Keyword(s):  
Receptor Binding ◽  
Conformational Changes ◽  
Hepatitis Virus ◽  
Mouse Hepatitis Virus ◽  
Envelope Proteins ◽  
Viral Envelope ◽  
S Protein ◽  
The Stability ◽  
Virus Fitness ◽  
Viral Envelope Proteins

ABSTRACTThe spike glycoprotein (S) of murine coronavirus mouse hepatitis virus (MHV) strain A59 uses murine carcinoembryonic antigen-related cell adhesion molecule 1a as its receptor for cell entry, but S protein can also be triggered in the absence of receptor by pH 8.0 alone at 37°C. The mechanism by which conformational changes of this S glycoprotein can be triggered by pH 8.0 has not yet been determined. Here, we show that MHV-A59 S protein is triggered by pH 8.0 at 37°C to induce receptor-independent syncytium (RIS) formation on 293T cells, and that the conformational changes in S proteins triggered by pH 8.0 are very similar to those triggered by receptor binding. We systemically mutated each of 15 histidine residues in S protein and found that H209 is essential for pH 8.0-triggered RIS formation, while H179, H441, H643, and H759 also play important roles in this process. Replacement of H209 with Ala had no effect on receptor binding, but in murine 17Cl.1 cells mutant H209A MHV-A59 showed delayed growth kinetics and was readily outcompeted by wild-type virus when mixed together, indicating that the H209A mutation caused a defect in virus fitness. Finally, the H209A mutation significantly increased the thermostability of S protein in its prefusion conformation, which may raise the energy barrier for conformational change of S protein required for membrane fusion and lead to a decrease in virus fitness in cell culture. Thus, MHV-A59 may have evolved to lower the stability of its S protein in order to increase virus fitness.IMPORTANCEEnveloped viruses enter cells through fusion of viral and cellular membranes, and the process is mediated by interactions between viral envelope proteins and their host receptors. In the prefusion conformation, viral envelope proteins are metastable, and activation to the fusion conformation is tightly regulated, since premature activation would lead to loss of viral infectivity. The stability of viral envelope proteins greatly influences their activation and virus fitness. Here, we report that, similar to the A82V mutation in Ebola glycoprotein, in the S glycoprotein of murine coronavirus MHV-A59, the histidine residue at position of 209 significantly affects the thermal stability of the S protein, determines whether S protein can be activated at 37°C by either pH 8.0 alone or by receptor binding, and affects viral fitness in cell culture. Thus, the spike glycoprotein of MHV-A59 has evolved to retain histidine at position 209 to optimize virus fitness.

scholarly journals Hydrophobic Inactivation of Influenza Viruses Confers Preservation of Viral Structure with Enhanced Immunogenicity

2008 ◽  
Vol 82 (9) ◽  
pp. 4612-4619 ◽  
Author(s):  
Yossef Raviv ◽  
Robert Blumenthal ◽  
S. Mark Tompkins ◽  
Jennifer Humberd ◽  
Robert J. Hogan ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Virus Infection ◽  
Cell Membrane ◽  
Target Cell ◽  
Envelope Proteins ◽  
Viral Envelope ◽  
Live Virus ◽  
Target Cell Membrane ◽  
Ph Dependent ◽  
Viral Envelope Proteins

ABSTRACT The use of inactivated influenza virus for the development of vaccines with broad heterosubtypic protection requires selective inactivation techniques that eliminate viral infectivity while preserving structural integrity. Here we tested if a hydrophobic inactivation approach reported for retroviruses could be applied to the influenza virus. By this approach, the transmembrane domains of viral envelope proteins are selectively targeted by the hydrophobic photoactivatable compound 1,5-iodonaphthyl-azide (INA). This probe partitions into the lipid bilayer of the viral envelope and upon far UV irradiation reacts selectively with membrane-embedded domains of proteins and lipids while the protein domains that localize outside the bilayer remain unaffected. INA treatment of influenza virus blocked infection in a dose-dependent manner without disrupting the virion or affecting neuraminidase activity. Moreover, the virus maintained the full activity in inducing pH-dependent lipid mixing, but pH-dependent redistribution of viral envelope proteins into the target cell membrane was completely blocked. These results indicate that INA selectively blocks fusion of the virus with the target cell membrane at the pore formation and expansion step. Using a murine model of influenza virus infection, INA-inactivated influenza virus induced potent anti-influenza virus serum antibody and T-cell responses, similar to live virus immunization, and protected against heterosubtypic challenge. INA treatment of influenza A virus produced a virus that is noninfectious, intact, and fully maintains the functional activity associated with the ectodomains of its two major envelope proteins, neuraminidase and hemagglutinin. When used as a vaccine given intranasally (i.n.), INA-inactivated influenza virus induced immune responses similar to live virus infection.

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