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Virus Nuclear Antigen (virus + nuclear_antigen)

Distribution by Scientific Domains
Life Sciences60%
Medical Sciences40%

Kinds of Virus Nuclear Antigen

  • barr virus nuclear antigen
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    Selected Abstracts

    Ebp2p, yeast homologue of a human protein that interacts with Epstein,Barr virus Nuclear Antigen 1, is required for pre-rRNA processing and ribosomal subunit assembly

    GENES TO CELLS, Issue 7 2000
    Rota Tsujii
    Background A defect in the secretory pathway causes the transcriptional repression of both rRNA and ribosomal protein genes in Saccharomyces cerevisiae, suggesting a coupling of ribosome synthesis and plasma membrane synthesis. Rrs1p, an essential nuclear protein, is required for the secretory response. Results EBP2, encoding the yeast homologue of a human protein that interacts with Epstein,Barr virus Nuclear Antigen 1, was cloned in a two-hybrid screen using RRS1 as a bait. The rrs1-1 mutation, which produces Rrs1p without the C-terminal half and causes a defect in the secretory response, almost abolished the interaction with Ebp2p. Ebp2p is essential for growth and is mainly localized in the nucleolus. The effects of Ebp2p depletion on ribosome biogenesis is quite similar to that of Rrs1p depletion; in the Ebp2p-depleted cells, the rate of pre-rRNA processing is slower, and significantly less mature 25S rRNA is produced compared to those in wild-type cells. The polysome pattern indicates that Ebp2p-depletion causes a decrease of 80S monosomes and polysomes, an accumulation of 40S subunits, and the appearance of half-mer polysomes. Conclusions Ebp2p is required for the maturation of 25S rRNA and 60S subunit assembly. Ebp2p may be one of the target proteins of Rrs1p for executing the signal to regulate ribosome biogenesis. [source]

    B-lymphocyte subpopulations are equally susceptible to Epstein,Barr virus infection, irrespective of immunoglobulin isotype expression

    IMMUNOLOGY, Issue 4 2003
    Barbro Ehlin-Henriksson
    Summary While Epstein,Barr virus (EBV) is known to establish latency in the memory B-cell compartment, there is controversy as to whether the memory or the naïve B cell is the initial target for infection. Here we have explored the infectability of the B-cell subsets contained in peripheral blood and tonsils, as distinguished by their surface expression of the immunoglobulin isotypes that help to define naïve and memory pools. First we show that both CD21 and major histocompatibility complex (MHC) class II molecules , respectively, the major receptor and co-receptor for EBV on B cells , are expressed at similar levels on blood and tonsillar B cells, irrespective of surface immunoglobulin class, indicating that each of the subsets demonstrate an equal potential, at least for infection. Then, following in vitro infection of total tonsillar B cells, we found that the relative frequencies of immunoglobulin (Ig)M-, IgG- and IgA-positive cells containing EBV-encoded Epstein,Barr virus nuclear antigen 5 (EBNA5) protein at 48 hr were similar to those of the starting population. However, IgD expression was uniformly decreased, probably as a consequence of cellular activation. These data indicate that recirculating B cells have both the potential for, and susceptibility to, initial infection by EBV, irrespective of the immunoglobulin isotype expressed. [source]

    Cell specific internal translation efficiency of Epstein,Barr virus present in solid organ transplant patients

    JOURNAL OF MEDICAL VIROLOGY, Issue 5 2007
    Åsa Isaksson
    Abstract The U leader exon in the 5, untranslated region of the Epstein,Barr virus nuclear antigen 1 (EBNA1) gene contains an internal ribosome entry site, the EBNA internal ribosome entry segment (IRES), which promotes cap-independent translation and increases the expression level of the EBNA1 protein. It was previously reported that immunosuppressed organ transplanted patients showed an alternatively spliced EBNA1 transcript, excluding the EBNA IRES element. To further investigate the function of the EBNA IRES, sequence analysis of the EBNA IRES mRNA was performed in samples from seven organ transplant patients. Two nucleotide changes, G,,,A at position 67531 and C,,,U at position 67585 were found in the EBNA IRES mRNA, relative to the corresponding genomic Epstein,Barr virus (EBV) sequence in all patients. Moreover, the patient derived EBNA IRES mRNA was shown to differ from the IRES mRNA derived from the cell line B95.8 at position 67531 and from the cell lines Rael and P3HR1 at positions 67531 and 67585. cDNA from the various EBNA IRES sequences were cloned into bicistronic vectors, respectively, and used in transient transfection experiments in six human cell lines. The patient specific sequence significantly decreased the IRES activity in T-cells, while the base changes had no significant impact on the activity in B- or in epithelial cells. The genetic mechanisms behind EBV-associated diseases are complex, involving gene regulation by alternative promoters, alternative splicing, and translational control. The nucleotide changes in the patient specific EBNA IRES transcript and its influence on the translational activity, might illustrate new strategies utilised by the EBV to adapt to the immune control in patients with EBV associated diseases. J. Med. Virol. 79:573,581, 2007. © 2007 Wiley-Liss, Inc. [source]

    Deiminated Epstein-Barr virus nuclear antigen 1 is a target of anti,citrullinated protein antibodies in rheumatoid arthritis

    ARTHRITIS & RHEUMATISM, Issue 3 2006
    Federico Pratesi
    Objective To test the hypothesis that deimination of viral sequences containing Arg,Gly repeats could generate epitopes recognized by anti,citrullinated protein antibodies (ACPAs) that are present in rheumatoid arthritis (RA) sera. Methods Multiple antigen peptides derived from Epstein-Barr virus (EBV),encoded Epstein-Barr nuclear antigen 1 (EBNA-1) were synthesized, substituting the arginines with citrulline, and were used to screen RA sera. Anti,cyclic citrullinated peptide antibodies were purified by affinity chromatography and tested on a panel of in vitro deiminated proteins. Their ability to bind in vivo deiminated proteins was evaluated by immunoprecipitation, using EBV-infected cell lines. Results Antibodies specific for a peptide corresponding to the EBNA-135,58 sequence containing citrulline in place of arginine (viral citrullinated peptide [VCP]) were detected in 50% of RA sera and in <5% of normal and disease control sera. In addition, affinity-purified anti-VCP antibodies from RA sera reacted with filaggrin-derived citrullinated peptides, with deiminated fibrinogen, and with deiminated recombinant EBNA-1. Moreover, anti-VCP antibodies immunoprecipitated, from the lysate of calcium ionophore,stimulated lymphoblastoid cell lines, an 80-kd band that was reactive with a monoclonal anti,EBNA-1 antibody and with anti,modified citrulline antibodies. Conclusion These data indicate that ACPAs react with a viral deiminated protein and suggest that EBV infection may play a role in the induction of these RA-specific antibodies. [source]