Gene Expression and Genome Replication in the Single-Stranded DNA Viruses

Author(s):  
Phoebe Lostroh
2015 ◽  
Vol 89 (22) ◽  
pp. 11734-11738 ◽  
Author(s):  
Stephanie Darbre ◽  
Susan Johnson ◽  
Sandra Kallert ◽  
Paul-Henri Lambert ◽  
Claire-Anne Siegrist ◽  
...  

Recombinant glycoprotein-deficient lymphocytic choriomeningitis virus-based vaccine vectors (rLCMV/ΔGP) are potent CD8+T cell inducers. To investigate the underlying molecular requirements, we generated a nucleoprotein-deficient vector counterpart (rLCMV/ΔNP). NP but not GP is a minimaltrans-acting factor for viral transcription and genome replication. We found that, unlike rLCMV/ΔGP, rLCMV/ΔNP failed to elicit detectable CD8+T cell responses unless NP wastranscomplemented in a transgenic host. Hence, NP-dependent intracellular gene expression is essential for LCMV vector immunogenicity.


2021 ◽  
Author(s):  
Nicolás Romero ◽  
Herman W. Favoreel

The nuclear factor kappa B (NF-κB) pathway is known to integrate signaling associated with very diverse intra- and extracellular stressors including virus infections, and triggers a powerful (pro-inflammatory) response through the expression of NF-κB-regulated genes. Typically, the NF-κB pathway collects and transduces threatening signals at the cell surface or in the cytoplasm leading to nuclear import of activated NF-κB transcription factors. In the current work, we demonstrate that the swine alphaherpesvirus pseudorabies virus (PRV) induces a peculiar mode of NF-κB activation known as “inside-out” NF-κB activation. We show that PRV triggers the DNA damage response (DDR) and that this DDR response drives NF-κB activation since inhibition of the nuclear ataxia telangiectasia-mutated (ATM) kinase, a chief controller of DDR, abolished PRV-induced NF-κB activation. Initiation of the DDR-NF-κB signaling axis requires viral protein synthesis but occurs before active viral genome replication. In addition, the initiation of the DDR-NF-κB signaling axis is followed by a virus-induced complete shutoff of NF-κB-dependent gene expression that depends on viral DNA replication. In summary, the results presented in this study reveal that PRV infection triggers a non-canonical DDR-NF-κB activation signaling axis and that the virus actively inhibits the (potentially antiviral) consequences of this pathway, by inhibiting NF-κB-dependent gene expression. IMPORTANCE: The NF-κB signaling pathway plays a critical role in coordination of innate immune responses that are of vital importance in the control of infections. The current report generates new insights in the interaction of the alphaherpesvirus pseudorabies virus (PRV) with the NF-κB pathway, as they reveal that (i) PRV infection leads to NF-κB activation via a peculiar “inside-out’ nucleus-to-cytoplasm signal that is triggered via the DNA damage response (DDR), (ii) the DDR-NF-κB signaling axis requires expression of viral proteins but is initiated before active PRV replication, and (iii) late viral factor(s) allow PRV to actively and efficiently inhibit NF-κB-dependent (pro-inflammatory) gene expression. These data suggest that activation of the DDR-NF-κB during PRV infection is host-driven and that its potential antiviral consequences are actively inhibited by the virus.


2014 ◽  
Author(s):  
◽  
Olufemi Fasina

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Viruses as obligate intracellular metabolic parasite require the capacity to orchestrate and modulate the host environment either in the nucleus or cytoplasm for their efficient reproductive life cycle. This warrants the use of diverse range of proteins expressed from the viral genome with the ability of regulating viral genome replication, transcription and translation, in addition antagonizing host factors inhibitory to the virus. Therefore, in order to achieve these goals, viruses utilizes gene expression strategies to expand their coding capacity. Gene expression mechanism such as transcription initiation, capping, splicing and 3�-end processing afford viruses the opportunities to utilize the eukaryotic metabolic machineries for generating proteome diversity. Parvoviruses and other DNA viruses effectively capitalize on their use of nuclear eukaryotic metabolic machineries to co-opt host cell factors for optimal replication and gene expression. Parvoviruses with small genome size and overlapping open reading frames utilize alternative transcription initiation, alternative splicing and alternative polyadenylation to co-ordinate the expression of its non-structural and structural proteins. In this work, we have characterized how two parvoviruses; Dependovirus AAV5 and Bocavirus Minute virus of canine (MVC) utilize alternative gene expression mechanisms and strategies to optimize expression of viral proteins from their genome.


2018 ◽  
Vol 6 (17) ◽  
Author(s):  
Mason Kerr ◽  
Karyna Rosario ◽  
Christopher C. M. Baker ◽  
Mya Breitbart

ABSTRACT Here, we describe four novel circular single-stranded DNA viruses discovered in fungus-farming termites ( Odontotermes sp.). The viruses, named termite-associated circular virus 1 (TaCV-1) through TaCV-4, are most similar to members of the family Genomoviridae and were widely detected in African termite mounds.


2015 ◽  
Vol 6 ◽  
Author(s):  
Mya Breitbart ◽  
Bayleigh E. Benner ◽  
Parker E. Jernigan ◽  
Karyna Rosario ◽  
Laura M. Birsa ◽  
...  

2012 ◽  
Vol 93 (5) ◽  
pp. 1046-1058 ◽  
Author(s):  
James C. Towler ◽  
Bahram Ebrahimi ◽  
Brian Lane ◽  
Andrew J. Davison ◽  
Derrick J. Dargan

Broad cell tropism contributes to the pathogenesis of human cytomegalovirus (HCMV), but the extent to which cell type influences HCMV gene expression is unclear. A bespoke HCMV DNA microarray was used to monitor the transcriptome activity of the low passage Merlin strain of HCMV at 12, 24, 48 and 72 h post-infection, during a single round of replication in human fetal foreskin fibroblast cells (HFFF-2s), human retinal pigmented epithelial cells (RPE-1s) and human astrocytoma cells (U373MGs). In order to correlate transcriptome activity with concurrent biological responses, viral cytopathic effect, growth kinetics and genomic loads were examined in the three cell types. The temporal expression pattern of viral genes was broadly similar in HFFF-2s and RPE-1s, but dramatically different in U373MGs. Of the 165 known HCMV protein-coding genes, 41 and 48 were differentially regulated in RPE-1s and U373MGs, respectively, compared with HFFF-2s, and 22 of these were differentially regulated in both RPE-1s and U373MGs. In RPE-1s, all differentially regulated genes were downregulated, but, in U373MGs, some were down- and others upregulated. Differentially regulated genes were identified among the immediate-early, early, early late and true-late viral gene classes. Grouping of downregulated genes according to function at landmark stages of the replication cycle led to the identification of potential bottleneck stages (genome replication, virion assembly, and virion maturation and release) that may account for cell type-dependent viral growth kinetics. The possibility that cell type-specific differences in expressed cellular factors are responsible for modulation of viral gene expression is discussed.


Author(s):  
Catherine D. Aimone ◽  
J. Steen Hoyer ◽  
Anna E. Dye ◽  
David O. Deppong ◽  
Siobain Duffy ◽  
...  

AbstractWe present an optimized protocol for enhanced amplification and enrichment of viral DNA for Next Generation Sequencing of begomovirus genomes. The rapid ability of these viruses to evolve threatens many crops and underscores the importance of using next generation sequencing efficiently to detect and understand the diversity of these viruses. We combined enhanced rolling circle amplification (RCA) with EquiPhi29 polymerase and size selection to generate a cost-effective, short-read sequencing method. This optimized protocol produced short-read sequencing with at least 50% of the reads mapping to the viral reference genome. We provide other insights into common misconceptions about RCA and lessons we have learned from sequencing single-stranded DNA viruses. Our protocol can be used to examine viral DNA as it moves through the entire pathosystem from host to vector, providing valuable information for viral DNA population studies, and would likely work well with other CRESS DNA viruses.HighlightsProtocol for short-read, high throughput sequencing of single-stranded DNA viruses using random primersComparison of the sequencing of total DNA versus size-selected DNAComparison of phi29 and Equiphi29 DNA polymerases for rolling circle amplification of viral single-stranded DNA genomes


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