scholarly journals Mechanism of Borna Disease Virus Entry into Cells

1998 ◽  
Vol 72 (1) ◽  
pp. 783-788 ◽  
Author(s):  
Daniel Gonzalez-Dunia ◽  
Beatrice Cubitt ◽  
Juan Carlos de la Torre
Keyword(s):  
Disease Virus ◽  
Virus Entry ◽  
Host Cells ◽  
Cell Surface Receptor ◽  
Animal Cells ◽  
Borna Disease Virus ◽  
C Terminus ◽  
Surface Receptor ◽  
Infected Cells ◽  
Borna Disease

ABSTRACT We have investigated the entry pathway of Borna disease virus (BDV). Virus entry was assessed by detecting early viral replication and transcription. Lysosomotropic agents (ammonium chloride, chloroquine, and amantadine), as well as energy depletion, prevented BDV infection, indicating that BDV enters host cells by endocytosis and requires an acidic intracellular compartment to allow membrane fusion and initiate infection. Consistent with this hypothesis, we observed that BDV-infected cells form extensive syncytia upon low-pH treatment. Entry of enveloped viruses into animal cells usually requires the membrane-fusing activity of viral surface glycoproteins (GPs). BDV GP is expressed as two products of 84 and 43 kDa (GP-84 and GP-43, respectively). We show here that only GP-43 is present at the surface of BDV-infected cells and therefore is likely the viral polypeptide responsible for triggering fusion events. We also present evidence that GP-43, which corresponds to the C terminus of GP-84, is generated by cleavage of GP-84 by the cellular protease furin. Hence, we propose that BDV GP-84 is involved in attachment to the cell surface receptor whereas its furin-cleaved product, GP-43, is involved in pH-dependent fusion after internalization of the virion by endocytosis.

scholarly journals N-Terminal Domain of Borna Disease Virus G (p56) Protein Is Sufficient for Virus Receptor Recognition and Cell Entry

2001 ◽  
Vol 75 (15) ◽  
pp. 7078-7085 ◽  
Author(s):  
Mar Perez ◽  
Michiko Watanabe ◽  
Michael A. Whitt ◽  
Juan Carlos de la Torre
Keyword(s):  
Amino Acids ◽  
G Protein ◽  
Disease Virus ◽  
Fluorescent Protein ◽  
Virus Entry ◽  
Surface Glycoprotein ◽  
Terminal Part ◽  
Borna Disease Virus ◽  
Receptor Recognition ◽  
Borna Disease

ABSTRACT Borna disease virus (BDV) surface glycoprotein (GP) (p56) has a predicted molecular mass of 56 kDa. Due to extensive posttranslational glycosylation the protein migrates as a polypeptide of 84 kDa (gp84). The processing of gp84 by the cellular protease furin generates gp43, which corresponds to the C-terminal part of gp84. Both gp84 and gp43 have been implicated in viral entry involving receptor-mediated endocytosis and pH-dependent fusion. We have investigated the domains of BDV p56 involved in virus entry. For this, we used a pseudotype approach based on a recently developed recombinant vesicular stomatitis virus (VSV) in which the gene for green fluorescent protein was substituted for the VSV G protein gene (VSVΔG*). Complementation of VSVΔG* with BDV p56 resulted in infectious VSVΔG* pseudotypes that contained both BDV gp84 and gp43. BDV-VSV chimeric GPs that contained the N-terminal 244 amino acids of BDV p56 and amino acids 421 to 511 of VSV G protein were efficiently incorporated into VSVΔG* particles, and the resulting pseudotype virions were neutralized by BDV-specific antiserum. These findings indicate that the N-terminal part of BDV p56 is sufficient for receptor recognition and virus entry.

scholarly journals Detection of a novel Borna disease virus-encoded 10 kDa protein in infected cells and tissues.

1997 ◽  
Vol 78 (10) ◽  
pp. 2459-2466 ◽  
Author(s):  
T Wehner ◽  
H Becht ◽  
K Frese ◽  
J A Richt ◽  
C Herden ◽  
...  
Keyword(s):  
Disease Virus ◽  
Borna Disease Virus ◽  
Infected Cells ◽  
Borna Disease

scholarly journals Authentic Borna disease virus transcripts are spliced less efficiently than cDNA-derived viral RNAs

2000 ◽  
Vol 81 (8) ◽  
pp. 1947-1954 ◽  
Author(s):  
Christian Jehle ◽  
W. Ian Lipkin ◽  
Peter Staeheli ◽  
Rosa M. Marion ◽  
Martin Schwemmle
Keyword(s):  
Disease Virus ◽  
Rna Virus ◽  
Borna Disease Virus ◽  
Viral Rnas ◽  
Negative Strand ◽  
Intron 1 ◽  
Splicing Pattern ◽  
Alternatively Spliced ◽  
Infected Cells ◽  
Borna Disease

Borna disease virus (BDV) is a non-segmented, negative-strand RNA virus that replicates and transcribes its genome in the nucleus of infected cells. It uses the cellular splicing machinery to generate a set of alternatively spliced mRNAs from the 2·8 and 7·1 kb primary transcripts, each harbouring two introns. To determine whether splicing of these transcripts is regulated by viral factors, the extent of splicing was studied in infected cells and COS-7 cells transiently transfected with plasmids encoding the 2·8 kb RNA of BDV. Unspliced RNA was found to be the most abundant RNA species in infected cells, whereas viral transcripts lacking both introns were only found in minute amounts. In sharp contrast, plasmid-derived 2·8 kb RNA was predominantly intron 1-spliced and double-spliced. Co-expression of the BDV proteins P, N and X did not influence splicing of plasmid-expressed 2·8 kb RNA. Furthermore, the splicing pattern did not change when the 2·8 kb RNA was expressed in BDV-infected cells. Based on these results we speculate that splicing of authentic BDV transcripts is tightly linked to transcription by the viral polymerase.

scholarly journals Characterization of Borna disease virus p56 protein, a surface glycoprotein involved in virus entry.

1997 ◽  
Vol 71 (4) ◽  
pp. 3208-3218 ◽  
Author(s):  
D Gonzalez-Dunia ◽  
B Cubitt ◽  
F A Grasser ◽  
J C de la Torre
Keyword(s):  
Disease Virus ◽  
Virus Entry ◽  
Protein A ◽  
Surface Glycoprotein ◽  
Borna Disease Virus ◽  
Borna Disease

scholarly journals Characterization of the Nuclear Localization Signal of the Borna Disease Virus Polymerase

2002 ◽  
Vol 76 (16) ◽  
pp. 8460-8467 ◽  
Author(s):  
Michelle Portlance Walker ◽  
W. Ian Lipkin
Keyword(s):  
Disease Virus ◽  
Nuclear Localization ◽  
Nuclear Localization Signal ◽  
Rna Virus ◽  
Flag Epitope ◽  
Borna Disease Virus ◽  
Localization Signal ◽  
Infected Cells ◽  
Pass Through ◽  
Borna Disease

ABSTRACT Borna disease virus (BDV) is a nonsegmented negative-strand RNA virus that replicates and transcribes its genome in the nucleus of infected cells. BDV proteins involved in replication and transcription must pass through the nuclear envelope to associate with the genomic viral RNA. The RNA-dependent RNA polymerase (L) of BDV is postulated to be the catalytic enzyme of replication and transcription. We demonstrated previously that BDV L localizes to the nucleus of BDV-infected cells and L-transfected cells. Nuclear localization of the protein presupposes the presence of a nuclear localization signal (NLS) within its primary amino acid sequence or cotransport to the nucleus with another karyophilic protein. Because L localized to the nucleus in the absence of other viral proteins, we investigated the possibility that L contains an NLS. The minimal sequence required for nuclear localization of L was identified by analyzing the subcellular distribution of deletion mutants of L fused to a flag epitope tag or β-galactosidase. Although the majority of the L fusion proteins localized to the cytoplasm of transfected BSR-T7 cells, a strong NLS (844RVVKLRIAP852) with basic and proline residues was identified. Mutation of this sequence resulted in cytoplasmic distribution of L, confirming that this sequence was necessary and sufficient to drive the nuclear localization of L.

Transcriptional control of Borna disease virus (BDV) in persistently BDV-infected cells

1999 ◽  
Vol 144 (10) ◽  
pp. 1937-1946 ◽  
Author(s):  
T. Mizutani ◽  
H. Inagaki ◽  
D. Hayasaka ◽  
S. Shuto ◽  
N. Minakawa ◽  
...  
Keyword(s):  
Disease Virus ◽  
Transcriptional Control ◽  
Borna Disease Virus ◽  
Infected Cells ◽  
Borna Disease

scholarly journals Characterization of the P Protein-Binding Domain on the 10-Kilodalton Protein of Borna Disease Virus

2000 ◽  
Vol 74 (7) ◽  
pp. 3413-3417 ◽  
Author(s):  
Tahir H. Malik ◽  
Masahiko Kishi ◽  
Patrick K. Lai
Keyword(s):  
Disease Virus ◽  
Nuclear Localization ◽  
Cell Nucleus ◽  
Binding Domain ◽  
Borna Disease Virus ◽  
Nuclear Localization Signals ◽  
P Protein ◽  
Infected Cells ◽  
Borna Disease

ABSTRACT The Borna disease virus (BDV) is the prototype member of the Bornaviridae, and it replicates in the cell nucleus. The BDV p24P and p40N proteins carry nuclear localization signals (NLS) and are found in the nuclei of infected cells. The BDV p10 protein does not have an NLS, but it binds with P and/or N and is translocated to the nucleus. Hence, p10 may play a role in the replication of BDV in the cell nucleus. Here, we show that the P-binding domain is located in the N terminus of p10 and that S3 and L16 are important for the interaction.

scholarly journals Borna Disease Virus Phosphoprotein Binds a Neurite Outgrowth Factor, Amphoterin/HMG-1

2001 ◽  
Vol 75 (18) ◽  
pp. 8742-8751 ◽  
Author(s):  
Wataru Kamitani ◽  
Yuko Shoya ◽  
Takeshi Kobayashi ◽  
Makiko Watanabe ◽  
Byeong-Jae Lee ◽  
...  
Keyword(s):  
Neurite Outgrowth ◽  
Disease Virus ◽  
Cell Lines ◽  
Cultured Cells ◽  
Borna Disease Virus ◽  
P24 Protein ◽  
Infected Cells ◽  
The Brain ◽  
Borna Disease

ABSTRACT The Borna disease virus (BDV) p24 phosphoprotein is an abundant protein in BDV-infected cultured cells and animal brains. Therefore, there is a possibility that binding of the p24 protein to cellular factor(s) induces functional alterations of infected neural cells in the brain. To identify a cellular protein(s) that interacts with BDV p24 protein, we performed far-Western blotting with extracts from various cell lines. Using recombinant p24 protein as a probe, we detected a 30-kDa protein in all cell lines examined. Binding between the 30-kDa and BDV p24 proteins was also demonstrated using BDV p24 affinity and ion-exchange chromatography columns. Microsequence analysis of the purified 30-kDa protein revealed that its N terminus showed complete homology with rat amphoterin protein, which is a neurite outgrowth factor abundant in the brain during development. Mammalian two-hybrid and immunoprecipitation analyses also confirmed that amphoterin is a specific target for the p24 protein in vivo. Furthermore, we showed that infection by BDV, as well as purified p24 protein in the medium, significantly decreased cell process outgrowth of cells grown on laminin, indicating the functional inhibition of amphoterin by interaction with the p24 protein. Immunohistochemical analysis revealed decreased levels of amphoterin protein at the leading edges of BDV-infected cells. Moreover, the expression of the receptor for advanced glycation end products, of which the extracellular moiety is a receptor for amphoterin, was not significantly activated in BDV-infected cells during the process of extension, suggesting that the secretion of amphoterin from the cell surface is inhibited by the binding of the p24 protein. These results suggested that BDV infection may cause direct damage in the developing brain by inhibiting the function of amphoterin due to binding by the p24 phosphoprotein.

scholarly journals Functional Characterization of the Major and Minor Phosphorylation Sites of the P Protein of Borna Disease Virus

2007 ◽  
Vol 81 (11) ◽  
pp. 5497-5507 ◽  
Author(s):  
Sonja Schmid ◽  
Daniel Mayer ◽  
Urs Schneider ◽  
Martin Schwemmle
Keyword(s):  
Disease Virus ◽  
Functional Characterization ◽  
Polymerase Activity ◽  
Viral Rna ◽  
Borna Disease Virus ◽  
Recombinant Viruses ◽  
Infected Cells ◽  
P Proteins ◽  
Borna Disease

ABSTRACT The phosphoprotein P of Borna disease virus (BDV) is an essential cofactor of the viral RNA-dependent RNA polymerase. It is preferentially phosphorylated at serine residues 26 and 28 by protein kinase C ε (PKCε) and, to a lesser extent, at serine residues 70 and 86 by casein kinase II (CKII). To determine whether P phosphorylation is required for viral polymerase activity, we generated P mutants lacking either the PKCε or the CKII phosphate acceptor sites by replacing the corresponding serine residues with alanine (A). Alternatively, these sites were replaced by aspartic acid (D) to mimic phosphorylation. Functional characterization of the various mutants in the BDV minireplicon assay revealed that D substitutions at the CKII sites inhibited the polymerase-supporting activity of P, while A substitutions maintained wild-type activity. Likewise, D substitutions at the PKC sites did not impair the cofactor function of BDV-P, whereas A substitutions at these sites led to increased activity. Interestingly, recombinant viruses could be rescued only when P mutants with modified PKCε sites were used but not when both CKII sites were altered. PKCε mutant viruses showed a reduced capacity to spread in cell culture, while viral RNA and protein expression levels in persistently infected cells were almost normal. Further mutational analyses revealed that substitutions at individual CKII sites were, with the exception of a substitution of A for S86, detrimental for viral rescue. These data demonstrate that, in contrast to other viral P proteins, the cofactor activity of BDV-P is negatively regulated by phosphorylation.

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