scholarly journals Identification of Regulatory Host Genes Involved in Sigma Virus Replication Using RNAi Knockdown in Drosophila

Insects ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 339 ◽  
Author(s):  
Liao ◽  
Wu ◽  
Tang ◽  
Tsai ◽  
Rouhová ◽  
...  
Keyword(s):  
Gene Expression ◽  
Viral Replication ◽  
Virus Replication ◽  
Persistent Infection ◽  
Copy Number ◽  
Viral Expression ◽  
Immune Pathways ◽  
Sigma Virus ◽  
Host Genes

The Drosophila melanogaster sigma virus, a member of the Rhabdoviridae family, specifically propagates itself in D. melanogaster. It contains six genes in the order of 3ʹ-N–P–X–M–G–L-5ʹ. The sigma virus is the only arthropod-specific virus of the Rhabdoviridae family. Sigma-virus-infected Drosophila may suffer from irreversible paralysis when exposed to a high CO2 concentration, but generally, no other symptoms are reported. A recent study reported that host gene expression in immune pathways was not changed in sigma-virus-infected Drosophila, which does not necessarily suggest that they are not involved in virus–host interactions. The present study aimed to identify host genes associated with sigma virus replication. Immune pathways JAK-STAT and IMD were selected for detailed study. The results showed that the genome copy number of the sigma virus increased after knocking down the immune pathway genes domeless and PGRP-LC in Drosophila S2 cells. The knocking down of domeless and PGRP-LC significantly up-regulated the expression of the L gene compared to the other viral genes. We propose that the immune pathways respond to sigma virus infection by altering L expression, hence suppressing viral replication. This effect was further tested in vivo, when D. melanogaster individuals injected with dsdome and dsPGRP-LC showed not only an increase in sigma virus copy number, but also a reduced survival rate when treated with CO2. Our study proved that host immunity influences viral replication, even in persistent infection. Knocking down the key components of the immune process deactivates immune controls, thus facilitating viral expression and replication. We propose that the immunity system of D. melanogaster regulates the replication of the sigma virus by affecting the L gene expression. Studies have shown minimal host–virus interaction in persistent infection. However, our study demonstrated that the immunity continued to affect viral replication even in persistent infection because knocking down the key components of the immune process disabled the relevant immune controls and facilitated viral expression and replication.

scholarly journals Oral Inoculation of Chickens with a Candidate Fowl Adenovirus 9 Vector

2013 ◽  
Vol 20 (8) ◽  
pp. 1189-1196 ◽  
Author(s):  
Li Deng ◽  
Shayan Sharif ◽  
Éva Nagy
Keyword(s):  
Gene Expression ◽  
Antibody Response ◽  
Virus Replication ◽  
Viral Genome ◽  
Copy Number ◽  
Cytokine Gene Expression ◽  
Genome Copy ◽  
Virus Shedding ◽  
Genome Copy Number

ABSTRACTFowl adenoviruses (FAdVs) are a potential alternative to human adenovirus-based vaccine vectors. Our previous studies demonstrated that a 2.4-kb region at the left end of the FAdV-9 genome is nonessential for virus replication and is suitable for the insertion or replacement of transgenes. Ourin vivostudy showed that the virus FAdV-9Δ4, lacking six open reading frames (ORFs) at the left end of its genome, replicates less efficiently than wild-type FAdV-9 (wtFAdV-9) in chickens that were infected intramuscularly. However, the fecal-oral route is the natural route of FAdV infection, and the oral administration of a vaccine confers some advantages compared to administration through other routes, especially when developing an adenovirus as a vaccine vector. Therefore, we sought to investigate the effects of FAdV-9 in orally inoculated chickens. In the present study, we orally inoculated specific-pathogen-free (SPF) chickens with FAdV-9 and FAdV-9Δ4 and assessed virus shedding, antibody response, and viral genome copy number and cytokine gene expression in tissues. Our data showed that FAdV-9Δ4 replicated less efficiently than did wtFAdV-9, as evidenced by reduced virus shedding in feces, lower viral genome copy number in tissues, and lower antibody response, which are consistent with the results of the intramuscular route of immunization. Furthermore, we found that both wtFAdV-9 and FAdV-9Δ4 upregulated the mRNA expression of alpha interferon (IFN-α), IFN-γ, and interleukin-12 (IL-12). In addition, there was a trend toward downregulation of IL-10 gene expression caused by both viruses. These findings indicate that one or more of the six deleted ORFs contribute to modulating the host response against virus infection as well as virus replicationin vivo.

B-Catenin Signaling Regulates the In Vivo Distribution of Hepatitis B Virus Biosynthesis across the Liver Lobule

2021 ◽  
Author(s):  
Grant Tarnow ◽  
Alan McLachlan
Keyword(s):  
Gene Expression ◽  
Transgenic Mice ◽  
Viral Replication ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Central Vein ◽  
Liver Lobule ◽  
Liver Gene ◽  
Mice Liver

β-catenin (Ctnnb1) supports high levels of liver gene expression in hepatocytes in proximity to the central vein functionally defining zone 3 of the liver lobule. This region of the liver lobule supports the highest levels of viral biosynthesis in wildtype HBV transgenic mice. Liver-specific β-catenin-null HBV transgenic mice exhibit a stark loss of high levels of pericentral viral biosynthesis. Additionally, viral replication that does not depend directly on β-catenin activity appears to expand to include hepatocytes of zone 1 of the liver lobule in proximity to the portal vein, a region of the liver that typically lacks significant HBV biosynthesis in wildtype HBV transgenic mice. While the average amount of viral RNA transcripts does not change, viral DNA replication is reduced approximately three-fold. Together, these observations demonstrate that β-catenin signaling represents a major determinant of HBV biosynthesis governing the magnitude and distribution of viral replication across the liver lobule in vivo. Additionally, these findings reveal a novel mechanism for the regulation of HBV biosynthesis that is potentially relevant to the expression of additional liver-specific genes. IMPORTANCE Viral biosynthesis is highest around the central vein in the HBV transgenic mouse model of chronic infection. The associated HBV biosynthetic gradient across the liver lobule is primarily dependent upon β-catenin. In the absence of β-catenin, the gradient of viral gene expression spanning the liver lobule is absent and HBV replication is reduced. Therefore, therapeutically manipulating β-catenin activity in the liver of chronic HBV carriers may reduce circulating infectious virions without greatly modulating viral protein production. Together, these change in viral biosynthesis might limit infection of additional hepatocytes while permitting immunological clearance of previously infected cells, potentially limiting disease persistence.

scholarly journals Temporal Expression Analysis of the Borrelia burgdorferi Paralogous Gene Family 54 Genes BBA64, BBA65, and BBA66 during Persistent Infection in Mice

2007 ◽  
Vol 75 (6) ◽  
pp. 2753-2764 ◽  
Author(s):  
Robert D. Gilmore ◽  
Rebekah R. Howison ◽  
Virginia L. Schmit ◽  
Andrew J. Nowalk ◽  
Dawn R. Clifton ◽  
...  
Keyword(s):  
Gene Expression ◽  
Borrelia Burgdorferi ◽  
Gene Family ◽  
Expression Profile ◽  
Persistent Infection ◽  
Adaptive Immune Response ◽  
Paralogous Gene ◽  
Reverse Transcription Pcr ◽  
Paralogous Gene Family

ABSTRACT Members of the Borrelia burgdorferi paralogous gene family 54 (pgf 54) are regulated by conditions simulating mammalian infection and are thought to be instrumental in borrelial host survival and pathogenesis. To explore the activities of these genes in vivo, a comprehensive analysis of pgf 54 genes BBA64, BBA65, and BBA66 was performed to assess the genetic stability, host antibody responses, and kinetics of gene expression in the murine model of persistent infection. DNA sequencing of pgf 54 genes obtained from reisolates at 1 year postinfection demonstrated that all genes of this family are stable and do not undergo recombination to generate variant antigens during persistent infection. Antibodies against BBA64 and BBA66 appeared soon after infection and were detectable throughout the infection, suggesting that there was gene expression during infection. However, quantitative reverse transcription-PCR revealed that BBA64 gene expression was considerably decreased in Borrelia residing in the mouse ear tissue compared to the expression in cultured spirochetes by 20 days postinfection and that the levels of expression remained low throughout the infection. Conversely, transcription of the BBA65 and BBA66 genes was increased, and both of these genes were continuously expressed until 100 days postinfection; this was followed by periods of differential expression late in infection. The expression profile of the BBA64 gene suggests that this gene has an important role during tick-to-host transmission and early infection, whereas the expression profile of the BBA65 and BBA66 genes suggests that these genes have a role in persistent infection. The differential regulation of pgf 54 genes observed during infection may help confer a survival advantage during persistent infection, influencing mechanisms for B. burgdorferi dissemination, tissue tropism, or evasion of the adaptive immune response.

scholarly journals Induction of type I interferons and interferon-inducible Mx genes during respiratory syncytial virus infection and reinfection in cotton rats

2008 ◽  
Vol 89 (1) ◽  
pp. 261-270 ◽  
Author(s):  
Lioubov M. Pletneva ◽  
Otto Haller ◽  
David D. Porter ◽  
Gregory A. Prince ◽  
Jorge C. G. Blanco
Keyword(s):  
Gene Expression ◽  
Respiratory Syncytial Virus ◽  
Virus Replication ◽  
Surrogate Marker ◽  
Type I Interferons ◽  
Type I ◽  
Dependent Manner ◽  
Type I Ifn ◽  
Syncytial Virus

Respiratory syncytial virus (RSV) is the primary cause of bronchiolitis in young children. In general, RSV is considered to be a poor inducer of type I (alpha/beta) interferons (IFNs). Measurement of active type I IFN production during infection in vivo is demanding, as multiple IFN subtypes with overlapping activities are produced. In contrast, Mx gene expression, which is tightly regulated by type I IFN expression, is easily determined. This study therefore measured Mx expression as a reliable surrogate marker of type I IFN activity during RSV infection in vivo in a cotton rat model. It was shown that expression of Mx genes was dramatically augmented in the lungs of infected animals in a dose- and virus strain-dependent manner. The expression of Mx genes in the lungs was paralleled by their induction in the nose and spleen, although in spleen no simultaneous virus gene expression was detected. Reinfection of RSV-immune animals leads to abortive virus replication in the lungs. Thus, type I IFN and Mx gene expression was triggered in reinfected animals, even though virus could not be isolated from their lungs. Furthermore, it was demonstrated that immunity to RSV wanes with time. Virus replication and Mx gene expression became more prominent with increasing intervals between primary infection and reinfection. These results highlight the role of type I IFN in modulation of the immune response to RSV.

scholarly journals Generation of a SARS-CoV-2 Replicon as a Model System to Dissect Virus Replication and Antiviral Inhibition

2020 ◽  
Author(s):  
Xi He ◽  
Shuo Quan ◽  
Min Xu ◽  
Silveria Rodriguez ◽  
Shih Lin Goh ◽  
...  
Keyword(s):  
Viral Replication ◽  
Virus Replication ◽  
Research Effort ◽  
System A ◽  
Antiviral Compounds ◽  
Culture Models ◽  
Level 3 ◽  
A Cell ◽  
Multiple Cell

SARS-CoV-2 research and antiviral discovery are hampered by the lack of a cell-based virus replication system that can be readily adopted without biosafety level 3 (BSL-3) restrictions. Here, the construction of a non-infectious SARS-CoV-2 reporter replicon and its application in deciphering viral replication mechanisms and evaluating SARS-CoV-2 inhibitors are presented. The replicon genome is replication competent but does not produce progeny virions. Its replication can be inhibited by RdRp mutations or by known SARS-CoV-2 antiviral compounds. Using this system, a high-throughput antiviral assay has also been developed. Significant differences in potencies of several SARS-CoV-2 inhibitors in different cell lines were observed, which highlights the challenges of discovering antivirals capable of inhibiting viral replication in vivo and the importance of testing compounds in multiple cell culture models. The generation of a SARS-CoV-2 replicon provides a powerful platform to expand the global research effort to combat COVID-19.

scholarly journals Human Papillomavirus Genotype 31 Does Not Express Detectable MicroRNA Levels during Latent or Productive Virus Replication

2006 ◽  
Vol 80 (21) ◽  
pp. 10890-10893 ◽  
Author(s):  
Xuezhong Cai ◽  
Gu Li ◽  
Laimonis A. Laimins ◽  
Bryan R. Cullen
Keyword(s):  
Human Papillomavirus ◽  
Viral Replication ◽  
Virus Replication ◽  
Human Cells ◽  
Human Papillomaviruses ◽  
Replication Cycle ◽  
Dna Viruses ◽  
Infected Cells ◽  
Productive Virus

ABSTRACT It has recently become clear that several pathogenic DNA viruses express virally encoded microRNAs in infected cells. In particular, numerous microRNAs have been identified in a range of human and animal herpesviruses, and individual microRNAs have also been identified in members of the polyoma- and adenovirus families. Although their functions remain largely unknown, it seems likely that these viral microRNAs play an important role in viral replication in vivo. Here we present an analysis of the microRNAs expressed in human cells during the latent and productive phases of the human papillomavirus genotype 31 (HPV31) replication cycle. Although over 500 cellular microRNAs were cloned and identified, not a single HPV31-specific microRNA was obtained. We therefore concluded that HPV31, and possibly human papillomaviruses in general, does not express viral microRNAs.

Evaluation of chemokine-ligand pathways in pretreatment tumor biopsies as predictive biomarker of response to adoptive therapy in metastatic melanoma patients.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 8576-8576 ◽  
Author(s):  
Davide Bedognetti ◽  
Sara Tomei ◽  
Tara L Spivey ◽  
Valeria De Giorgi ◽  
Maria Libera Ascierto ◽  
...  
Keyword(s):  
Gene Expression ◽  
Copy Number Variation ◽  
Copy Number ◽  
Target Genes ◽  
Adoptive Therapy ◽  
Over Expression ◽  
Number Variation ◽  
Pre Treatment ◽  
Tumor Biopsies

8576 Background: Adoptive therapy with tumor infiltrating lymphocytes (TILs) induces objective responses (OR) in approximately 50% of patients with metastatic melanoma. The recruitment of TILs through CXCR3/CCR5-ligand chemokines is believed critical for immune-mediated rejection. Here, we investigated the predictive role of a gene-signature based on CXCR3/CCR5-ligand chemokine transcripts in pre-treatment melanoma biopsies, its biological role and its relation with CCR5-Δ32 polymorphism, which encodes a protein not expressed on cell surface. Methods: Expression of CXCR3/CXCR3-ligand transcripts (i.e CXCL9, 10, 11) and CCR5/CCR5-ligand transcripts (i.e. CCL3, 4, 5) were assessed in 113 pre-treatment tumor biopsies from patients enrolled in adoptive therapy trials: 24 patients achieved a complete remission (CR), 34 a partial remission (PR), and 55 did not respond (NR). Copy number variation and gene expression profile of these target genes were assessed in 15 biopsy-derived cell lines. CCR5-Δ32 was assessed by sequencing germinal DNA. Results: CXCL9, 10 and 11 and CCL5 clustered together and were selected for hierarchical clustering analysis based on the mean-centered gene expression values. A signature characterized by the over-expression of these genes was associated with the likelihood to achieve a clinical response (OR rate: PR+CR: 65% vs 38%, High vs Low, respectively, P=0.015). Neither correlation between the copy number variation and the gene-expression of the corresponding genes, nor correlation between the transcripts of the investigated genes between tumor biopsies and the matched cell lines was detected. Transcript expression of the target genes did not differ between CCR5-Δ32 (n =20) and wild type patients (n=93). Conclusions: Coordinate over-expression of CXCR3/CCR5 ligands in pre-treatment tumor samples was associated with responsiveness to treatment. However, the lack of correlation between in vivo and ex vivo data suggest the inflammatory status characterized by the up-regulation of these inflammatory chemokine genes is an in vivo multifactorial phenomenon.

scholarly journals Alpha/Beta Interferons Regulate Murine Gammaherpesvirus Latent Gene Expression and Reactivation from Latency

2005 ◽  
Vol 79 (22) ◽  
pp. 14149-14160 ◽  
Author(s):  
Erik S. Barton ◽  
Mary L. Lutzke ◽  
Rosemary Rochford ◽  
Herbert W. Virgin
Keyword(s):  
Gene Expression ◽  
Virus Infection ◽  
Virus Replication ◽  
Critical Role ◽  
Latent Virus ◽  
Viral Reactivation ◽  
Murine Gammaherpesvirus ◽  
Infected Cells ◽  
Alpha Beta

ABSTRACT Alpha/beta interferon (IFN-α/β) protects the host from virus infection by inhibition of lytic virus replication in infected cells and modulation of the antiviral cell-mediated immune response. To determine whether IFN-α/β also modulates the virus-host interaction during latent virus infection, we infected mice lacking the IFN-α/β receptor (IFN-α/βR−/−) and wild-type (wt; 129S2/SvPas) mice with murine gammaherpesvirus 68 (γHV68), a lymphotropic gamma-2-herpesvirus that establishes latent infection in B cells, macrophages, and dendritic cells. IFN-α/βR−/− mice cleared low-dose intranasal γHV68 infection with wt kinetics and harbored essentially wt frequencies of latently infected cells in both peritoneum and spleen by 28 days postinfection. However, latent virus in peritoneal cells and splenocytes from IFN-α/βR−/− mice reactivated ex vivo with >40-fold- and 5-fold-enhanced efficiency, respectively, compared to wt cells. Depletion of IFN-α/β from wt mice during viral latency also significantly increased viral reactivation, demonstrating an antiviral function of IFN-α/β during latency. Viral reactivation efficiency was temporally regulated in both wt and IFN-α/βR−/− mice. The mechanism of IFN-α/βR action was distinct from that of IFN-γR, since IFN-α/βR−/− mice did not display persistent virus replication in vivo. Analysis of viral latent gene expression in vivo demonstrated specific upregulation of the latency-associated gene M2, which is required for efficient reactivation from latency, in IFN-α/βR−/− splenocytes. These data demonstrate that an IFN-α/β-induced pathway regulates γHV68 gene expression patterns during latent viral infection in vivo and that IFN-α/β plays a critical role in inhibiting viral reactivation during latency.

scholarly journals SARS-CoV-2 evasion from ADAR hyper-editing is both genome-encoded and sustained by the virus replication strategy

2021 ◽  
Author(s):  
Enrico Bortoletto ◽  
Paola Venier ◽  
Maxwell Shapiro ◽  
Andrea Leonardi ◽  
Umberto Rosani
Keyword(s):  
Viral Replication ◽  
Virus Replication ◽  
Rna Seq ◽  
Low Level ◽  
Replication Strategy

Abstract We evaluated the role of ADAR during in-vivo SARS-CoV-2 infection, identifying ADAR-mediated hyper-editing only in 49 RNA-seq samples at a low level. Hyper-editing of host dsRNAs appeared not influenced by SARS-CoV-2 infection and showed higher efficiency compared to viral editing. Conversely, in mouse samples we found abundant hyper-editing with similar efficiency between host and SARS-CoV-2 RNAs. Underrepresentation of dinucleotide motifs along coronavirus ORFs suggested that SARS-CoV-2 resistance to ADAR hyper-editing is both evolutionary-encoded and sustained by viral replication strategy.

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