scholarly journals Rana grylio virus (RGV) envelope protein 2L: subcellular localization and essential roles in virus infectivity revealed by conditional lethal mutant

2014 ◽  
Vol 95 (3) ◽  
pp. 679-690 ◽  
Author(s):  
Li-Bo He ◽  
Fei Ke ◽  
Jun Wang ◽  
Xiao-Chan Gao ◽  
Qi-Ya Zhang
Keyword(s):  
Virus Infection ◽  
Envelope Protein ◽  
Core Gene ◽  
Envelope Proteins ◽  
Current Data ◽  
Viral Envelope ◽  
Virus Infectivity ◽  
Lethal Mutant ◽  
Transfected Cells ◽  
Conditional Lethal Mutant

Rana grylio virus (RGV) is a pathogenic iridovirus that has resulted in high mortality in cultured frog. Here, an envelope protein gene, 2L, was identified from RGV and its possible role in virus infection was investigated. Database searches found that RGV 2L had homologues in all sequenced iridoviruses and is a core gene of iridoviruses. Western blotting detection of purified RGV virions confirmed that 2L protein was associated with virion membrane. Fluorescence localization revealed that 2L protein co-localized with viral factories in RGV infected cells. In co-transfected cells, 2L protein co-localized with two other viral envelope proteins, 22R and 53R. However, 2L protein did not co-localize with the major capsid protein of RGV in co-transfected cells. Meanwhile, fluorescence observation showed that 2L protein co-localized with endoplasmic reticulum, but did not co-localize with mitochondria and Golgi apparatus. Moreover, a conditional lethal mutant virus containing the lac repressor/operator system was constructed to investigate the role of RGV 2L in virus infection. The ability to form plaques and the virus titres were strongly reduced when expression of 2L was repressed. Therefore, the current data showed that 2L protein is essential for virus infection. Our study is the first report, to our knowledge, of co-localization between envelope proteins in iridovirus and provides new insights into the understanding of envelope proteins in iridovirus.

scholarly journals Identification and characterization of a novel envelope protein in Rana grylio virus

2008 ◽  
Vol 89 (8) ◽  
pp. 1866-1872 ◽  
Author(s):  
Zhe Zhao ◽  
Fei Ke ◽  
You-Hua Huang ◽  
Jiu-Gang Zhao ◽  
Jian-Fang Gui ◽  
...  
Keyword(s):  
Western Blot ◽  
Envelope Protein ◽  
Virus Assembly ◽  
Structural Features ◽  
Envelope Proteins ◽  
Current Data ◽  
Viral Envelope ◽  
Viral Envelope Protein ◽  
Infected Cells

Viral envelope proteins have been proposed to play significant roles in virus infection and assembly. In this study, an envelope protein gene, 53R, was cloned and characterized from Rana grylio virus (RGV), a member of the family Iridoviridae. Database searches found its homologues in all sequenced iridoviruses, and sequence alignment revealed several conserved structural features shared by virus capsid or envelope proteins: a myristoylation site, two predicted transmembrane domains and two invariant cysteine residues. Subsequently, RT-PCR and Western blot detection revealed that the transcripts encoding RGV 53R and the protein itself appeared late during infection of fathead minnow cells and that their appearance was blocked by viral DNA replication inhibitor, indicating that RGV 53R is a late expression gene. Moreover, immunofluorescence localization found an association of 53R with virus factories in RGV-infected cells, and this association was further confirmed by expressing a 53R–GFP fusion protein in pEGFP-N3/53R-transfected cells. Furthermore, detergent extraction and Western blot detection confirmed that RGV 53R was associated with virion membrane. Therefore, the current data suggest that RGV 53R is a novel viral envelope protein and that it may play an important role in virus assembly. This is thought to be the first report on a viral envelope protein that is conserved in all sequenced iridoviruses.

scholarly journals Characterization of the VP39 envelope protein from Singapore grouper iridovirus

2015 ◽  
Vol 61 (12) ◽  
pp. 924-937 ◽  
Author(s):  
Honglian Zhang ◽  
Sheng Zhou ◽  
Liqun Xia ◽  
Xiaohong Huang ◽  
Youhua Huang ◽  
...  
Keyword(s):  
Envelope Protein ◽  
Core Gene ◽  
Immunofluorescence Assay ◽  
Current Data ◽  
Viral Envelope ◽  
Economic Losses ◽  
Immunogold Electron Microscopy ◽  
Viral Envelope Protein ◽  
Drug Inhibition

Singapore grouper iridovirus (SGIV) is a major pathogen that causes heavy economic losses to the grouper aquaculture industry in China and Southeast Asian countries. In the present study, a viral envelope protein, VP39, encoded by SGIV ORF39L, was identified and characterized. SGIV ORF39L was found in all sequenced iridoviruses and is now considered to be a core gene of the family Iridoviridae. ORF39L was classified as a late gene during in vitro infection using reverse transcription–polymerase chain reaction, western blotting, and a drug inhibition analysis. An indirect immunofluorescence assay revealed that the VP39 protein was confined to the cytoplasm, especially at viral assembly sites. Western blot and matrix-assisted laser desorption/ionization-time of flight tandem mass spectrometry analyses suggested that VP39 is an envelope protein. Immunogold electron microscopy further confirmed that VP39 is a viral envelope protein. Furthermore, a mouse anti-VP39 polyclonal antibody exhibited SGIV-neutralizing activity in vitro, suggesting that VP39 is involved in SGIV infection. Taken together, the current data suggest that VP39 represents a conserved envelope protein of iridoviruses that contributes to viral infection.

scholarly journals Protective effect of low-concentration chlorine dioxide gas against influenza A virus infection

2008 ◽  
Vol 89 (1) ◽  
pp. 60-67 ◽  
Author(s):  
Norio Ogata ◽  
Takashi Shibata
Keyword(s):  
Influenza Virus ◽  
Virus Infection ◽  
Influenza A Virus ◽  
Chlorine Dioxide ◽  
Influenza A ◽  
Influenza Virus Infection ◽  
Envelope Proteins ◽  
Viral Envelope ◽  
Exposure Level ◽  
Low Concentration

Influenza virus infection is one of the major causes of human morbidity and mortality. Between humans, this virus spreads mostly via aerosols excreted from the respiratory system. Current means of prevention of influenza virus infection are not entirely satisfactory because of their limited efficacy. Safe and effective preventive measures against pandemic influenza are greatly needed. We demonstrate that infection of mice induced by aerosols of influenza A virus was prevented by chlorine dioxide (ClO2) gas at an extremely low concentration (below the long-term permissible exposure level to humans, namely 0.1 p.p.m.). Mice in semi-closed cages were exposed to aerosols of influenza A virus (1 LD50) and ClO2 gas (0.03 p.p.m.) simultaneously for 15 min. Three days after exposure, pulmonary virus titre (TCID50) was 102.6±1.5 in five mice treated with ClO2, whilst it was 106.7±0.2 in five mice that had not been treated (P=0.003). Cumulative mortality after 16 days was 0/10 mice treated with ClO2 and 7/10 mice that had not been treated (P=0.002). In in vitro experiments, ClO2 denatured viral envelope proteins (haemagglutinin and neuraminidase) that are indispensable for infectivity of the virus, and abolished infectivity. Taken together, we conclude that ClO2 gas is effective at preventing aerosol-induced influenza virus infection in mice by denaturing viral envelope proteins at a concentration well below the permissible exposure level to humans. ClO2 gas could therefore be useful as a preventive means against influenza in places of human activity without necessitating evacuation.

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.

scholarly journals HIV-1 Envelope Glycoprotein at the Interface of Host Restriction and Virus Evasion

Viruses ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 311 ◽  
Author(s):  
Saina Beitari ◽  
Yimeng Wang ◽  
Shan-Lu Liu ◽  
Chen Liang
Keyword(s):  
Viral Infection ◽  
Adaptive Immunity ◽  
Viral Entry ◽  
Envelope Protein ◽  
Envelope Proteins ◽  
Viral Envelope ◽  
Innate Immune ◽  
Host Restriction ◽  
Hiv 1 ◽  
Viral Envelope Proteins

Without viral envelope proteins, viruses cannot enter cells to start infection. As the major viral proteins present on the surface of virions, viral envelope proteins are a prominent target of the host immune system in preventing and ultimately eliminating viral infection. In addition to the well-appreciated adaptive immunity that produces envelope protein-specific antibodies and T cell responses, recent studies have begun to unveil a rich layer of host innate immune mechanisms restricting viral entry. This review focuses on the exciting progress that has been made in this new direction of research, by discussing various known examples of host restriction of viral entry, and diverse viral countering strategies, in particular, the emerging role of viral envelope proteins in evading host innate immune suppression. We will also highlight the effective cooperation between innate and adaptive immunity to achieve the synergistic control of viral infection by targeting viral envelope protein and checking viral escape. Given that many of the related findings were made with HIV-1, we will use HIV-1 as the model virus to illustrate the basic principles and molecular mechanisms on host restriction targeting HIV-1 envelope protein.

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.

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