scholarly journals Herpesvirus Saimiri Open Reading Frame 50 (Rta) Protein Reactivates the Lytic Replication Cycle in a Persistently Infected A549 Cell Line

2001 ◽  
Vol 75 (8) ◽  
pp. 4008-4013 ◽  
Author(s):  
Delyth J. Goodwin ◽  
Matthew S. Walters ◽  
Peter G. Smith ◽  
Mathias Thurau ◽  
Helmut Fickenscher ◽  
...  
Keyword(s):  
Cell Line ◽  
A549 Cell ◽  
Molecular Mechanisms ◽  
Lytic Replication ◽  
Replication Cycle ◽  
Open Reading Frame ◽  
Herpesvirus Saimiri ◽  
A549 Cell Line ◽  
Reading Frame ◽  
Virus Recovery

ABSTRACT Herpesviruses occur in two distinct forms of infection, lytic replication and latent persistence. In this study, we investigated the molecular mechanisms that govern the latent-lytic switch in the prototype gamma-2 herpesvirus, herpesvirus saimiri (HVS). We utilized a persistently HVS-infected A549 cell line, in which HVS DNA is stably maintained as nonintegrated circular episomes, to assess the role of the open reading frame 50 (ORF 50) (Rta) proteins in the latent-lytic switch. Northern blot analysis and virus recovery assays determined that the ORF 50a gene product, when expressed under the control of a constitutively active promoter, was sufficient to reactivate the entire lytic replication cycle, producing infectious virus particles. Furthermore, although the ORF 50 proteins of HVS strains A11 and C488 are structurally divergent, they were both capable of inducing the lytic replication cycle in this model of HVS latency.

scholarly journals The Open Reading Frame (ORF) 50a Gene Product Regulates ORF 57 Gene Expression in Herpesvirus Saimiri

1998 ◽  
Vol 72 (3) ◽  
pp. 1967-1973 ◽  
Author(s):  
Adrian Whitehouse ◽  
Matthew Cooper ◽  
Kersten T. Hall ◽  
David M. Meredith
Keyword(s):  
Gene Expression ◽  
Gene Product ◽  
Feedback Mechanism ◽  
Replication Cycle ◽  
Open Reading Frame ◽  
Herpesvirus Saimiri ◽  
Reading Frame ◽  
Barr Virus ◽  
Epstein Barr ◽  
Virus Replication Cycle

ABSTRACT We have previously demonstrated that open reading frame (ORF) 50 and ORF 57 encode transcriptional regulating genes in herpesvirus saimiri. ORF 50, a homolog of Epstein-Barr virus R protein, is a sequence-specific transactivator, whereas ORF 57 acts posttranscriptionally. In this report, we demonstrate that the ORF 57 gene is regulated by the ORF 50a gene product. We show that the ORF 57 gene is expressed at basal levels early in the virus replication cycle and that thereafter it is transactivated by the ORF 50a gene product, due to an increase in RNA levels. As it has been shown that the ORF 57 gene product downregulates ORF 50a due to the presence of its intron, these combined observations identify a feedback mechanism modulating gene expression in herpesvirus saimiri, whereby ORF 50a transcription is downregulated by the ORF 57 gene product, a gene which it specifically transactivates. Furthermore, we propose that the intron-containing ORF 57 gene downregulates itself by the same mechanism as that for ORF 50a, as both genes are downregulated at similar times during the replication cycle.

Detection of eight antibodies in cancer patients’ sera against proteins derived from the adenocarcinoma A549 cell line using proteomics-based analysis

2006 ◽  
Vol 838 (1) ◽  
pp. 15-20 ◽  
Author(s):  
Toyofumi Nakanishi ◽  
Toru Takeuchi ◽  
Kazuhito Ueda ◽  
Hitoshi Murao ◽  
Akira Shimizu
Keyword(s):  
Cell Line ◽  
Cancer Patients ◽  
A549 Cell ◽  
A549 Cell Line

scholarly journals The Immediate-Early Gene Product Encoded by Open Reading Frame 57 of Herpesvirus Saimiri Modulates Gene Expression at a Posttranscriptional Level

1998 ◽  
Vol 72 (1) ◽  
pp. 857-861 ◽  
Author(s):  
Adrian Whitehouse ◽  
Matthew Cooper ◽  
David M. Meredith
Keyword(s):  
Gene Expression ◽  
Gene Product ◽  
Target Gene ◽  
Immediate Early Gene ◽  
Open Reading Frame ◽  
Early Gene ◽  
Immediate Early ◽  
Herpesvirus Saimiri ◽  
Amino Acid Homology ◽  
Reading Frame

ABSTRACT The herpesvirus saimiri (HVS) immediate-early gene product encoded by open reading frame (ORF) 57 shares limited amino acid homology with HSV-1 ICP27 and Epstein-Barr virus BMLF1, both regulatory proteins. The ORF 57 gene has been proposed to be spliced based on the genome sequence, and here we confirm the intron-exon structure of the gene. We also demonstrate that a cDNA construct of the ORF 57 gene product represses the transactivating capability of the ORF 50a gene product (which is produced from a spliced transcript), but activates that of ORF 50b (an unspliced transcript). Further analyses with cotransfection experiments show that ORF 57 can either activate or repress expression from a range of both early and late HVS promoters, depending on the target gene. These results indicate that repression of gene expression mediated by the ORF 57 gene product is dependent on the presence of an intron within the target gene encoding region. Furthermore, Northern blot analysis demonstrates that the levels of mRNA transcribed from genes not containing an intron are not significantly affected in the presence of the ORF 57 gene product. This suggests that it regulates gene expression through a posttranscriptional mechanism.

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