A capsid protein of nonenveloped Bluetongue virus exhibits membrane fusion activity

Forzan, Mario; Wirblich, Christoph; Roy, Polly

doi:10.1073/pnas.0306448101

Cited by 60 publications

(74 citation statements)

References 39 publications

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“…To test this hypothesis, we investigated P2-membrane interactions by expressing P2 in insect cells and displaying it on the cell surface, by using a vector that was used to study the bluetongue virus VP5 fusion activities (14). By using pAcVSVG, we prepared a recombinant baculovirus that expressed RDV P2 or P8 after a signal peptide derived from the baculovirus gp64 signal peptide and fused at the C terminus to the transmembrane domain of the vesicular stomatitis virus (VSV) G protein ( Fig.…”

Section: P2 Induced Membrane Fusion In Insect Cellsmentioning

confidence: 99%

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The P2 capsid protein of the nonenveloped rice dwarf phytoreovirus induces membrane fusion in insect host cells

Zhou

Wei

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Insect transmission is an essential process of infection for numerous plant and animal viruses. How an insect-transmissible plant virus enters an insect cell to initiate the infection cycle is poorly understood, especially for nonenveloped plant and animal viruses. The capsid protein P2 of rice dwarf virus (RDV), which is nonenveloped, is necessary for insect transmission. Here, we present evidence that P2 shares structural features with membrane-fusogenic proteins encoded by enveloped animal viruses. When RDV P2 was ectopically expressed and displayed on the surface of insect Spodoptera frugiperda cells, it induced membrane fusion characterized by syncytium formation at low pH. Mutational analyses identified the N-terminal and a heptad repeat as being critical for the membrane fusion-inducing activity. These results are corroborated with results from RDV-infected cells of the insect vector leafhopper. We propose that the RDV P2-induced membrane fusion plays a critical role in viral entry into insect cells. Our report that a plant viral protein can induce membrane fusion has broad significance in studying the mechanisms of virus entry into insect cells and insect transmission of nonenveloped plant and animal viruses.

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Section: P2 Induced Membrane Fusion In Insect Cellsmentioning

confidence: 99%

“…The VP5 of bluetongue virus acts not only as a membrane penetration protein but also as a fusion protein that induces syncytium formation when it is fused to a transmembrane anchor and expressed on the cell surface. By short exposure to a low pH, the VP5 undergoes conformational changes that enable it to interact with cellular membranes (14).…”

mentioning

confidence: 99%

The P2 capsid protein of the nonenveloped rice dwarf phytoreovirus induces membrane fusion in insect host cells

Zhou

Wei

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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“…Analysis of the VP5 sequence using secondary structure prediction algorithms indicates that this protein is predominantly -helical, with an amphipathic helical domain at the N terminus followed by a coiled coil domain, thus sharing structural features with class I fusion proteins of enveloped viruses [74]. Furthermore, VP5 undergoes pH-dependent conformational changes that allow membrane fusion and syncytium formation [25]. The syncytium formation by VP5 is inhibited in the presence of VP2 when expressed in a membrane-anchored form.…”

Section: Vp5mentioning

confidence: 99%

“…VP2 dissociates from the outer capsid layer in early endosomes. Acidification induces VP5 fusion with the endosomal membrane [25], delivering the transcriptionally active core into the cell cytoplasm. Like other members of the Reoviridae family, BTV replicates within the cytoplasm of infected cells.…”

Section: Btv Life Cyclementioning

confidence: 99%

Bluetongue virus: virology, pathogenesis and immunity

et al. 2008

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-Bluetongue (BT) virus, an orbivirus of the Reoviridae family encompassing 24 known serotypes, is transmitted to ruminants via certain species of biting midges (Culicoides spp.) and causes thrombo-hemorrhagic fevers mainly in sheep. During the 20th century, BTV was endemic in sub-tropical regions but in the last ten years, new strains of BTV (serotypes 1, 2, 4, 8, 9, 16) have appeared in Europe leading to a devastating disease in naive sheep and bovine herds (serotype 8). BTV enters into insect cells via the viral inner core VP7 protein and in mammalian cells via the external capsid VP2 haemagglutinin, which is the major determinant of BTV serotype and neutralization. BTV replicates in mononuclear phagocytes and endothelial cells where it induces expression of inflammatory cytokines as well as apoptosis. BTV can remain as nonreplicating entities concealed in erythrocytes for up to five months. Homologous protection against one BTV serotype involves neutralizing antibodies and T cell responses directed to the external VP2 and VP5 proteins, whereas heterologous protection is supported by T cells directed to the NS1 non structural protein and inner core proteins.

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“…For FACS analysis, Sf9 cells were infected as mentioned above and the analysis was performed as described previously [23], on a Becton-Dickinson FACSCalibur analyser running CellQuest software (Becton-Dickinson).…”

Section: Immunofluorescence and Fluorescence-activated Cell Sorter (Fmentioning

confidence: 99%

Efficient assembly and release of SARS coronavirus‐like particles by a heterologous expression system

2004

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Virus-like particles (VLPs) produced by recombinant expression of the major viral structural proteins could be an attractive method for severe acute respiratory syndrome (SARS) control. In this study, using the baculovirus system, we generated recombinant viruses that expressed S, E, M and N structural proteins of SARS-CoV either individually or simultaneously. The expression level, size and authenticity of each recombinant SARS-CoV protein were determined. In addition, immunofluorescence and FACS analysis confirmed the cell surface expression of the S protein. Co-infections of insect cells with two recombinant viruses demonstrated that M and E could assemble readily to form smooth surfaced VLPs. On the other hand, simultaneous high level expression of S, E and M by a single recombinant virus allowed the very efficient assembly and release of VLPs. These data demonstrate that the VLPs are morphological mimics of virion particles. The high level expression of VLPs with correct S protein conformation by a single recombinant baculovirus offers a potential candidate vaccine for SARS.

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A capsid protein of nonenveloped Bluetongue virus exhibits membrane fusion activity

Cited by 60 publications

References 39 publications

The P2 capsid protein of the nonenveloped rice dwarf phytoreovirus induces membrane fusion in insect host cells

The P2 capsid protein of the nonenveloped rice dwarf phytoreovirus induces membrane fusion in insect host cells

Bluetongue virus: virology, pathogenesis and immunity

Efficient assembly and release of SARS coronavirus‐like particles by a heterologous expression system

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