1
|
Wahid A, Hamzawy MA, Khalifa MMA, Gad GFM, Bekhit A, Abdelwahab SF. RNA protein kinase SNP at -226 C<T is a biomarker for the clearance of HCV among Egyptian patients. Immunol Invest 2019; 48:211-221. [PMID: 30080984 DOI: 10.1080/08820139.2018.1493496] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND RNA-dependant protein kinase R (PKR) is a primary mediator in the defence mechanism of interferon against viral replication and pathogenesis during Hepatitis C virus (HCV) infection. In the present study, we have examined the role of Single Nucleotide Polymorphisms (SNPs) in the promoter region of PKR and the serum level of the same protein on the outcome of HCV-infected Egyptian patients. PATIENTS AND METHODS Genomic DNA was extracted from a total of 135 subjects, including 15 healthy controls, 40 HCV spontaneous resolvers (SRs), and 80 patients with chronic HCV infection. PKR genotyping was assessed using DNA sequencing. Finally, serum levels of PKR, TNF-α, INF-γ, and IL-10 were measured using ELISA technique. RESULTS Serum levels of PKR, TNF-α, and INF-γ showed a significant increase in SRs as compared to chronic HCV patients. On the other hand, serum levels of IL-10 were significantly higher in chronic HCV patients compared to SRs. The present study demonstrated two novel SNPs in the PKR promoter region: at -226 C/T and -141 C/G. The PKR SNP at -226 C < T correlated with HCV-infected patients (genotype 4a) outcome among Egyptians. Our data showed the unique presence of the TT genotype in SRs group (three patients: 7.5%) in PKR -226 C/T. Interestingly, subjects with the TT genotype were more likely to clear their HCV infection than those with the CC genotype. CONCLUSION Our work provides more detail about PKR gene polymorphism in HCV genotype 4a as a new clinical tool for anticipating HCV-4a infection outcome.
Collapse
Affiliation(s)
- Ahmed Wahid
- a Department of Pharmacology and Toxicology, Faculty of Pharmacy , Alexandria University , Alexandria , Egypt
| | - Mustafa A Hamzawy
- b Department of Biochemistry, Faculty of Pharmacy , Minia University , Minia , Egypt
| | - Mohamad M A Khalifa
- c Department of Pharmacology, Faculty of Pharmacy , Minia University , Minia , Egypt
| | - Gamal F M Gad
- d Department of Microbiology and Immunology, Faculty of Pharmacy , Minia University , Minia , Egypt
| | - Amany Bekhit
- b Department of Biochemistry, Faculty of Pharmacy , Minia University , Minia , Egypt
| | - Sayed F Abdelwahab
- e Department of Microbiology and Immunology, Faculty of Medicine , Minia University , Minia , Egypt
- f Department of Microbiology , College of Pharmacy, Taif University , KSA
| |
Collapse
|
2
|
Feng Q, Yao J, Zhou G, Xia W, Lyu J, Li X, Zhao T, Zhang G, Zhao N, Yang J. Quantitative Proteomic Analysis Reveals That Arctigenin Alleviates Concanavalin A-Induced Hepatitis Through Suppressing Immune System and Regulating Autophagy. Front Immunol 2018; 9:1881. [PMID: 30177931 PMCID: PMC6109684 DOI: 10.3389/fimmu.2018.01881] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 07/30/2018] [Indexed: 12/24/2022] Open
Abstract
Concanavalin A-induced autoimmune hepatitis is a well-established experimental model for immune-mediated liver injury. It has been widely used in the therapeutic studies of immune hepatitis. The in-depth analysis of dysregulated proteins from comparative proteomic results indicated that the activation of immune system resulted in the deregulation of autophagy. Follow-up studies validated that some immune related proteins, including Stat1, Pkr, Atg7, and Adrm1, were indeed upregulated. The accumulations of LC3B-II and p62 were confirmed by immunohistochemistry and Western blot analyses. Arctigenin pretreatment significantly alleviated the liver injury, as evidenced by biochemical and histopathological investigations, whose protective effects were comparable with Prednisone acetate and Cyclosporin A. Arctigenin pretreatment decreased the levels of IL-6 and IFN-γ, but increased the ones of IL-10. Next, the quantitative proteomic analysis demonstrated that ARC pretreatment suppressed the activation of immune system through the inhibition of IFN-γ signaling, when it downregulated the protein expressions of Stat1, P-Stat1, Pkr, P-Pkr, Bnip3, Beclin1, Atg7, LC3B, Adrm1, and p62. Meanwhile, Arctigenin pretreatment also reduced the gene expressions of Stat1, Pkr, and Atg7. These results suggested that Arctigenin alleviated autophagy as well as apoptosis through inhibiting IFN-γ/IL-6/Stat1 pathway and IL-6/Bnip3 pathway. In summary, the comparative proteomic analysis revealed that the activation of immune system led to Concanavalin A-induced hepatitis. Both autophagy and apoptosis had important clinical implications for the treatment of immune hepatitis. Arctigenin might exert great therapeutic potential in immune-mediated liver injury.
Collapse
Affiliation(s)
- Qin Feng
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China.,Center for New Drug Pharmacological Research of Lunan Pharmaceutical Group, State Key Laboratory, Generic Manufacture Technology of Chinese Traditional Medicine, Linyi, China
| | - Jingchun Yao
- Center for New Drug Pharmacological Research of Lunan Pharmaceutical Group, State Key Laboratory, Generic Manufacture Technology of Chinese Traditional Medicine, Linyi, China
| | - Ge Zhou
- Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
| | - Wenkai Xia
- Center for New Drug Pharmacological Research of Lunan Pharmaceutical Group, State Key Laboratory, Generic Manufacture Technology of Chinese Traditional Medicine, Linyi, China
| | - Jingang Lyu
- Center for New Drug Pharmacological Research of Lunan Pharmaceutical Group, State Key Laboratory, Generic Manufacture Technology of Chinese Traditional Medicine, Linyi, China
| | - Xin Li
- Center for New Drug Pharmacological Research of Lunan Pharmaceutical Group, State Key Laboratory, Generic Manufacture Technology of Chinese Traditional Medicine, Linyi, China
| | - Tao Zhao
- Center for New Drug Pharmacological Research of Lunan Pharmaceutical Group, State Key Laboratory, Generic Manufacture Technology of Chinese Traditional Medicine, Linyi, China
| | - Guimin Zhang
- Center for New Drug Pharmacological Research of Lunan Pharmaceutical Group, State Key Laboratory, Generic Manufacture Technology of Chinese Traditional Medicine, Linyi, China.,School of Pharmacy, Linyi University, Linyi, China
| | - Ningwei Zhao
- Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China.,Shimadzu Biomedical Research Laboratory, Shanghai, China
| | - Jie Yang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China.,State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing, China
| |
Collapse
|
3
|
Watanabe T, Imamura T, Hiasa Y. Roles of protein kinase R in cancer: Potential as a therapeutic target. Cancer Sci 2018; 109:919-925. [PMID: 29478262 PMCID: PMC5891186 DOI: 10.1111/cas.13551] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 02/15/2018] [Accepted: 02/17/2018] [Indexed: 01/13/2023] Open
Abstract
Double‐stranded (ds) RNA‐dependent protein kinase (PKR) is a ubiquitously expressed serine/threonine protein kinase. It was initially identified as an innate immune antiviral protein induced by interferon (IFN) and activated by dsRNA. PKR is recognized as a key executor of antiviral host defense. Moreover, it contributes to inflammation and immune regulation through several signaling pathways. In addition to IFN and dsRNA, PKR is activated by multiple stimuli and regulates various signaling pathways including the mitogen‐activated protein kinase (MAPK) and nuclear factor kappa‐light‐chain‐enhancer of activated B cells pathways. PKR was initially thought to be a tumor suppressor as a result of its ability to suppress cell growth and interact with major tumor suppressor genes. However, in several types of malignant disease, such as colon and breast cancers, its role remains controversial. In hepatocellular carcinoma, hepatitis C virus (HCV) is the main cause of liver cancer, and PKR inhibits HCV replication, indicating its role as a tumor suppressor. However, PKR is overexpressed in cirrhotic patients, and acts as a tumor promoter through enhancement of cancer cell growth by mediating MAPK or signal transducer and activator of transcription pathways. Moreover, PKR is reportedly required for the activation of inflammasomes and influences metabolic disorders. In the present review, we introduce the multifaceted roles of PKR such as antiviral function, tumor cell growth, regulation of inflammatory immune responses, and maintaining metabolic homeostasis; and discuss future perspectives on PKR biology including its potential as a therapeutic target for liver cancer.
Collapse
Affiliation(s)
- Takao Watanabe
- Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Toon, Japan
| | - Takeshi Imamura
- Department of Molecular Medicine for Pathogenesis, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.,Translational Research Center, Ehime University Hospital, Toon, Japan
| | - Yoichi Hiasa
- Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Toon, Japan
| |
Collapse
|
4
|
Metz P, Dazert E, Ruggieri A, Mazur J, Kaderali L, Kaul A, Zeuge U, Windisch MP, Trippler M, Lohmann V, Binder M, Frese M, Bartenschlager R. Identification of type I and type II interferon-induced effectors controlling hepatitis C virus replication. Hepatology 2012; 56:2082-93. [PMID: 22711689 DOI: 10.1002/hep.25908] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Accepted: 06/05/2012] [Indexed: 12/12/2022]
Abstract
UNLABELLED Persistent infection with hepatitis C virus (HCV) can lead to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma. All current therapies of hepatitis C include interferon-alpha (IFN-α). Moreover, IFN-gamma (IFN-γ), the only type II IFN, strongly inhibits HCV replication in vitro and is the primary mediator of HCV-specific antiviral T-cell responses. However, for both cytokines the precise set of effector protein(s) responsible for replication inhibition is not known. The aim of this study was the identification of IFN-α and IFN-γ stimulated genes (ISGs) responsible for controlling HCV replication. We devised an RNA interference (RNAi)-based "gain of function" screen and identified, in addition to known ISGs earlier reported to suppress HCV replication, several new ones with proven antiviral activity. These include IFIT3 (IFN-induced protein with tetratricopeptide repeats 3), TRIM14 (tripartite motif containing 14), PLSCR1 (phospholipid scramblase 1), and NOS2 (nitric oxide synthase 2, inducible). All ISGs identified in this study were up-regulated both by IFN-α and IFN-γ, demonstrating a substantial overlap of HCV-specific effectors induced by either cytokine. Nevertheless, some ISGs were more specific for IFN-α or IFN-γ, which was most pronounced in case of PLSCR1 and NOS2 that were identified as main effectors of IFN-γ-mediated anti-HCV activity. Combinatorial knockdowns of ISGs suggest additive or synergistic effects demonstrating that with either IFN, inhibition of HCV replication is caused by the combined action of multiple ISGs. CONCLUSION Our study identifies a number of novel ISGs contributing to the suppression of HCV replication by type I and type II IFN. We demonstrate a substantial overlap of antiviral programs triggered by either cytokine and show that suppression of HCV replication is mediated by the concerted action of multiple effectors.
Collapse
Affiliation(s)
- Philippe Metz
- Department of Molecular Virology, University of Heidelberg, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
5
|
|
6
|
Kang JI, Kwon SN, Park SH, Kim YK, Choi SY, Kim JP, Ahn BY. PKR protein kinase is activated by hepatitis C virus and inhibits viral replication through translational control. Virus Res 2009; 142:51-6. [PMID: 19189853 DOI: 10.1016/j.virusres.2009.01.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Revised: 01/09/2009] [Accepted: 01/09/2009] [Indexed: 02/05/2023]
Abstract
Hepatitis C virus (HCV) infection is currently treated with IFNalpha-based therapy but little is known how IFNalpha inhibits HCV replication. We show here that HCV JFH1 infection of human hepatoma Huh-7 cells leads to the activation of IFN-inducible protein kinase PKR and phosphorylation of the translation initiation factor eIF2alpha. Compared to a control cell HCV replication was significantly elevated in a PKR-knockdown cell, giving rise to a 10-fold higher viral titer, and was less sensitive to IFNalpha treatment. Conversely, transient expression of PKR inhibited HCV replication in a kinase-dependent manner with concomitant increase of eIF2alpha phosphorylation. Further, expression of a phospho-mimetic eIF2alpha mutant moderately inhibited HCV replication. Together, these results demonstrate that PKR is activated by HCV infection and plays a critical antiviral role through inhibition of viral protein translation.
Collapse
Affiliation(s)
- Ju-Il Kang
- School of Life Sciences & Biotechnology, Korea University, 5-1 Anamdong, Seoul 136-701, Republic of Korea
| | | | | | | | | | | | | |
Collapse
|
7
|
Tokumoto Y, Hiasa Y, Horiike N, Michitaka K, Matsuura B, Chung RT, Onji M. Hepatitis C virus expression and interferon antiviral action is dependent on PKR expression. J Med Virol 2007; 79:1120-7. [PMID: 17596833 DOI: 10.1002/jmv.20902] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Interferon (IFN)-inducible double-stranded RNA-activated protein kinase (PKR) is thought to play a key antiviral role against hepatitis C virus (HCV). However, demonstrating the importance of PKR expression on HCV protein synthesis in the presence or absence of IFN has proven difficult in vivo. In the present experiment, full-length HCV constructs were transiently transfected into two cell lines stably expressing T7 RNA polymerase. HCV expression was monitored under conditions of upregulated or downregulated PKR expression. In addition, IFN was monitored during downregulation of PKR. HCV expression effectively increased PKR expression, as well as that of its regulated proteins. PKR was obviously knocked down by PKR-specific siRNA, which resulted in significantly increased HCV core protein levels. Conversely, over-expression of PKR significantly suppressed HCV core levels in both cell lines. Furthermore, IFN induced high levels of PKR, whereas downregulation of PKR reversed IFN's antiviral effects and increased HCV core levels. Based on these results, it appears that HCV protein expression is directly dependent on PKR expression. PKR is antiviral toward HCV and responsible for IFN's effect against HCV.
Collapse
Affiliation(s)
- Yoshio Tokumoto
- Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime, Japan
| | | | | | | | | | | | | |
Collapse
|
8
|
Zirger JM, Barcia C, Liu C, Puntel M, Mitchell N, Campbell I, Castro M, Lowenstein PR. Rapid upregulation of interferon-regulated and chemokine mRNAs upon injection of 108 international units, but not lower doses, of adenoviral vectors into the brain. J Virol 2007; 80:5655-9. [PMID: 16699048 PMCID: PMC1472125 DOI: 10.1128/jvi.00166-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The innate immune response, characterized by the rapid induction of proinflammatory genes, plays an important role in immune responses to viral vectors utilized in gene therapy. We demonstrate that several innate proinflammatory mRNAs, i.e., those coding for the interferon (IFN)-regulated proteins interferon regulatory factor 1, 2',5'-oligoadenylate synthetase, and double-stranded-RNA-dependent protein kinase as well as those coding for the chemokines RANTES, IFN-gamma-inducible protein 10, and monocyte chemoattractant protein 1, were all increased in a statistically significant manner in response to 1 x 10(8) IU, but not lower doses, of a first-generation adenovirus injected into the naïve brain. This indicates the presence of a threshold dosage of adenovirus needed to elicit an acute innate inflammatory response.
Collapse
Affiliation(s)
- Jeffrey M Zirger
- Board of Governors' Gene Therapeutics Research Institute, Cedars-Sinai Medical Center, 8700 Beverly Blvd., Los Angeles, CA 90048, USA
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Taniguchi H, Iwasaki Y, Takahashi A, Shimomura H, Moriya A, Yu PC, Umeoka F, Fujioka SI, Koide N, Shiratori Y. Intrahepatic mRNA Levels of Type I Interferon Receptor and Interferon-Stimulated Genes in Genotype 1b Chronic Hepatitis C. Intervirology 2006; 50:32-9. [PMID: 17164555 DOI: 10.1159/000096310] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Accepted: 01/10/2006] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE The aim of this study was to determine the association between pretreatment intrahepatic mRNA levels of interferon receptor and interferon-stimulated genes and response to interferon therapy for genotype 1b chronic hepatitis C. METHODS Forty-four patients with genotype 1b chronic hepatitis C who underwent liver biopsy and then received interferon therapy participated in this study. Pretreatment intrahepatic mRNA levels of interferon receptor genes (IFNAR1, IFNAR2b, and IFNAR2c) and interferon-stimulated genes (OAS1 and PKR) were quantified by competitive polymerase chain reaction. RESULTS In the genes examined, only IFNAR1 mRNA level was significantly higher in patients with sustained virological and biochemical response to interferon therapy versus those with nonsustained response (p < 0.01). Moreover, mRNA expression ratios of IFNAR1 to IFNAR2 were also significantly higher in patients with sustained virological and biochemical response to IFN therapy (p < 0.01 and p < 0.05, respectively). On the other hand, mRNA levels of IFNAR2b, IFNAR2c, and PKR were significantly higher in patients with histologically active or advanced liver rather than patients with mild or less advanced liver. CONCLUSIONS High intrahepatic mRNA levels of IFNAR1 and mRNA ratio of IFNAR1 to IFNAR2 before treatment may be associated with a favorable response to interferon therapy.
Collapse
MESH Headings
- 2',5'-Oligoadenylate Synthetase/genetics
- 2',5'-Oligoadenylate Synthetase/metabolism
- Adult
- Antiviral Agents/pharmacology
- Antiviral Agents/therapeutic use
- Female
- Hepatitis C, Chronic/drug therapy
- Hepatitis C, Chronic/pathology
- Hepatitis C, Chronic/virology
- Humans
- Interferon-alpha/pharmacology
- Interferon-alpha/therapeutic use
- Interferon-beta/pharmacology
- Interferon-beta/therapeutic use
- Liver/metabolism
- Liver/pathology
- Male
- Middle Aged
- Polymerase Chain Reaction
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Viral/blood
- Receptor, Interferon alpha-beta/genetics
- Receptor, Interferon alpha-beta/metabolism
- Treatment Outcome
- eIF-2 Kinase/genetics
- eIF-2 Kinase/metabolism
Collapse
Affiliation(s)
- Hideaki Taniguchi
- Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Effect of an epoxy derivative of 2′5′-trioligoadenylate on human neuroblastoma cells. NEUROPHYSIOLOGY+ 2006. [DOI: 10.1007/s11062-006-0029-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
11
|
Brand S, Beigel F, Olszak T, Zitzmann K, Eichhorst ST, Otte JM, Diebold J, Diepolder H, Adler B, Auernhammer CJ, Göke B, Dambacher J. IL-28A and IL-29 mediate antiproliferative and antiviral signals in intestinal epithelial cells and murine CMV infection increases colonic IL-28A expression. Am J Physiol Gastrointest Liver Physiol 2005; 289:G960-8. [PMID: 16051921 DOI: 10.1152/ajpgi.00126.2005] [Citation(s) in RCA: 164] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Human cytomegalovirus virus (CMV) is a major cause of morbidity and mortality in immunocompromised individuals. Recently, a novel group of cytokines [interleukin (IL)-28A/B and IL-29, also termed interferon (IFN)-lambdas] has been described. Here, we demonstrate that intestinal epithelial cell (IEC) lines as well as murine and human colonic tissue express the IFN-lambda receptor subunits IL-28R and IL-10R2. IL-28A and IL-29 binding to their receptor complex activates ERK-1/2 and stress-activated protein kinase/c-Jun NH2-terminal kinase MAPKs and Akt, resulting in increased IL-8 protein expression. IFN-lambdas also induce phosphorylation of signal transducer and activator of transcription 1 and significantly increase mRNA expression of suppressor of cytokine signaling 3 and the antiviral proteins myxovirus resistance A and 2',5'-oligoadenylate synthetase. These signals result in an up to 83% reduction of cells positive for human CMV immediate-early protein after human CMV infection. In mice, IL-28A mRNA expression is upregulated after infection with murine CMV in vivo. Both IL-28A and IL-29 significantly decrease cell proliferation but have no effect on Fas-induced apoptosis. In conclusion, IECs express functional receptors for IFN-lambdas, which mediate antiviral and antiproliferative signals in IECs, suggesting a potential for therapeutic use in certain viral infections and as (antiproliferative) anticancer therapy.
Collapse
Affiliation(s)
- Stephan Brand
- Department of Medicine II, University-Hospital Munich-Grosshadern, University of Munich, D-81377 Munich, Germany.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Gómez CE, Vandermeeren AM, García MA, Domingo-Gil E, Esteban M. Involvement of PKR and RNase L in translational control and induction of apoptosis after Hepatitis C polyprotein expression from a vaccinia virus recombinant. Virol J 2005; 2:81. [PMID: 16156900 PMCID: PMC1242258 DOI: 10.1186/1743-422x-2-81] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Accepted: 09/12/2005] [Indexed: 12/17/2022] Open
Abstract
Background Hepatitis C virus (HCV) infection is of growing concern in public health with around 350 million chronically infected individuals worldwide. Although the IFN-α/rivabirin is the only approved therapy with 10–30% clinical efficacy, the protective molecular mechanism involved during the treatment is still unknown. To analyze the effect of HCV polyprotein expression on the antiviral response of the host, we developed a novel vaccinia virus (VV)-based delivery system (VT7-HCV7.9) where structural and nonstructural (except part of NS5B) proteins of HCV ORF from genotype 1b are efficiently expressed and produced, and timely regulated in mammalian cell lines. Results Regulated transcript production and viral polypeptide processing was demonstrated in various cell lines infected with the recombinant VT7-HCV7.9, indicating that the cellular and viral proteolytic machineries are functional within these cells. The inducible expression of the HCV polyprotein by VV inhibits the synthesis of both host and viral proteins over the time and also induces apoptosis in HeLa and HepG2-infected cells. These effects occur accompanying with the phosphorylation of the translation initiation factor eIF-2α. In cells co-infected with VT7-HCV7.9 and a recombinant VV expressing the dominant negative eIF-2α-S51A mutant in the presence of the inductor isopropyl-thiogalactoside (IPTG), protein synthesis is rescued. The IFN-inducible protein kinase PKR is responsible for the translational block, as demonstrated with PKR-/- and PKR+/+ cell lines. However, apoptosis induced by VT7-HCV7.9 is mediated by the RNase L pathway, in a PKR-independent manner. Conclusion These findings demonstrate the antiviral relevance of the proteins induced by interferon, PKR and RNase L during expression from a VV recombinant of the HCV polyprotein in human cell lines. HCV polyprotein expression caused a severe cytopathological effect in human cells as a result of inhibition of protein synthesis and apoptosis induction, triggered by the activation of the IFN-induced enzymes PKR and RNase L systems. Thus, the virus-cell system described here highlights the relevance of the IFN system as a protective mechanism against HCV infection.
Collapse
Affiliation(s)
- Carmen E Gómez
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma, 28049 Madrid, Spain
| | - Andrée Marie Vandermeeren
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma, 28049 Madrid, Spain
| | - María Angel García
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma, 28049 Madrid, Spain
| | - Elena Domingo-Gil
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma, 28049 Madrid, Spain
| | - Mariano Esteban
- Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología, CSIC, Campus Universidad Autónoma, 28049 Madrid, Spain
| |
Collapse
|
13
|
Helbig KJ, Lau DTY, Semendric L, Harley HAJ, Beard MR. Analysis of ISG expression in chronic hepatitis C identifies viperin as a potential antiviral effector. Hepatology 2005; 42:702-10. [PMID: 16108059 DOI: 10.1002/hep.20844] [Citation(s) in RCA: 190] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Interferon (IFN) alpha inhibits hepatitis C virus (HCV) replication both clinically and in vitro; however, the complete spectrum of interferon-stimulated genes (ISGs) expressed in the HCV-infected liver or the genes responsible for control of HCV replication have not been defined. To better define ISG expression in the chronically infected HCV liver, DNA microarray analysis was performed on 9 individuals with chronic hepatitis C (CHC). A total of 232 messenger RNAs were differentially regulated in CHC compared with nondiseased liver controls. A significant proportion of these were potential ISGs that were transcriptionally elevated, suggesting an ongoing response to endogenous IFN and/or double-stranded RNA. One ISG significantly elevated in all patients was viperin, an evolutionary conserved ISG that has antiviral activity against human cytomegalovirus. Stimulation of Huh-7 and HepG2 cells with IFN-alpha or -gamma revealed viperin is predominantly a type I ISG. Furthermore, viperin expression could also be induced following transfection of Huh-7 cells with either poly(I:C) or HCV RNA. Transient expression of viperin in cells harboring the HCV genomic replicon resulted in a significant decrease in HCV replication, suggesting that viperin has anti-HCV activity. In conclusion, even in the face of a persistent HCV infection, there is an active ISG antiviral cellular response, highlighting the complexity of the host viral relationship. Furthermore, ISG viperin has anti-HCV activity in vitro; we postulate that viperin, along with other ISGs, acts to limit HCV replication.
Collapse
Affiliation(s)
- Karla J Helbig
- Infectious Diseases Laboratories and Hanson Institute, Institute of Medical and Veterinary Science, Adelaide, South Australia
| | | | | | | | | |
Collapse
|
14
|
Desloges N, Rahaus M, Wolff MH. Varicella-zoster virus does not significantly induce cell defence mechanism mediated by the 2-5A/RNase L pathway during its replication cycle. Med Microbiol Immunol 2005; 194:25-31. [PMID: 15107989 DOI: 10.1007/s00430-004-0220-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The 2-5A/RNase L pathway belongs to the antiviral system induced by interferon (IFN). RNase L is an inactive endoribonuclease which is activated by 2'-5' oligoadenylate (2-5A) synthesized by 2',5'-oligoadenylate synthetases. Once activated, RNase L cleaves mRNA, inhibiting the protein synthesis, as well as 28S and 18S ribosomal RNA (rRNA), leading to ribosomal inactivation. In this study, we investigate the role of the RNase L pathway as a cell defence mechanism during Varicella-zoster virus (VZV) replication, and the importance of a 68-kDa protein named RNase L inhibitor (RLI), which specifically inhibits RNase L. We demonstrate that the RNase L and RLI transcripts levels remain constant in VZV-infected cells for 24 h and 12 h, respectively, after which they decrease until the end of the viral cycle. VZV does not significantly modulate the protein level of RNase L during the course of infection. Using an rRNA cleavage assay to analyse the RNase L catalytic activity, we demonstrate that VZV replication leads to a minimal cleavage of rRNA. Moreover, the overexpression of RLI in a permissive cell line has no significant effect on the VZV replication. We conclude that RNase L does not constitute a major cell defence mechanism against the VZV infection.
Collapse
Affiliation(s)
- Nathalie Desloges
- University of Witten/Herdecke, Institute of Microbiology and Virology, Germany
| | | | | |
Collapse
|
15
|
Miller K, McArdle S, Gale MJ, Geller DA, Tenoever B, Hiscott J, Gretch DR, Polyak SJ. Effects of the hepatitis C virus core protein on innate cellular defense pathways. J Interferon Cytokine Res 2005; 24:391-402. [PMID: 15296650 DOI: 10.1089/1079990041535647] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The hepatitis C virus (HCV) core protein is thought to contribute to HCV pathogenesis through its interaction with various signal transduction pathways. In this study, we explored the interaction of the core protein with innate defense pathways (interferon [IFN] regulatory factor [IRF], Jak-Stat, and inducible nitric oxide synthase [iNOS]) in HeLa and Huh7 human cell lines. Expression of a patient-derived genotype 1b core protein activated human IRF-1 and guanylate-binding protein-2 (GBP-2) promoters, induced IRF-1 mRNA, but failed to induce IRF-3 phosphorylation. HCV core protein caused dose-dependent induction of the IFN-beta promoter and IFN-beta mRNA but not the IFN-alpha1 and IFN-alpha4 promoters. In the presence of IFN-alpha, core expression was associated with increased IFN-stimulated gene factor 3 (ISGF3) binding to the IFN-stimulated response element (ISRE) and tyrosine phosphorylation of Stat1. Core expression resulted in dose-dependent activation of the ISRE and gamma activated sequence (GAS) promoters, in both the absence and the presence of either IFN-alpha or IFN-gamma. Core stimulated the human iNOS promoter and induced iNOS protein. The data indicate that HCV core can modulate IRF, Jak-Stat, and iNOS pathways and suggest mechanisms by which core could affect HCV persistence and pathogenesis.
Collapse
Affiliation(s)
- Kristen Miller
- Virology Division, Department of Laboratory Medicine, University of Washington, Seattle, WA 98104-2499, USA
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Bigger CB, Guerra B, Brasky KM, Hubbard G, Beard MR, Luxon BA, Lemon SM, Lanford RE. Intrahepatic gene expression during chronic hepatitis C virus infection in chimpanzees. J Virol 2004; 78:13779-92. [PMID: 15564486 PMCID: PMC533929 DOI: 10.1128/jvi.78.24.13779-13792.2004] [Citation(s) in RCA: 220] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Accepted: 07/30/2004] [Indexed: 12/24/2022] Open
Abstract
Hepatitis C virus (HCV) infections represent a global health problem and are a major contributor to end-stage liver disease including cirrhosis and hepatocellular carcinoma. An improved understanding of the parameters involved in disease progression is needed to develop better therapies and diagnostic markers of disease manifestation. To better understand the dynamics of host gene expression resulting from persistent virus infection, DNA microarray analyses were conducted on livers from 10 chimpanzees persistently infected with HCV. A total of 162 genes were differentially regulated in chronically infected animals compared to uninfected controls. Many genes exhibited a remarkable consistency in changes in expression in the 10 chronically infected animals. A second method of analysis identified 971 genes altered in expression during chronic infection at a 99% confidence level. As with acute-resolving HCV infections, many interferon (IFN)-stimulated genes (ISGs) were transcriptionally elevated, suggesting an ongoing response to IFN and/or double-stranded RNA which is amplified in downstream ISG expression. Thus, persistent infection with HCV results in a complex and partially predictable pattern of gene expression, although the underlying mechanisms regulating the different pathways are not well defined. A single genotype 3-infected animal was available for analysis, and this animal exhibited reduced levels of ISG expression compared to levels of expression with genotype 1 infections and increased expression of a number of genes potentially involved in steatosis. Gene expression data in concert with other observations from HCV infections permit speculation on the regulation of specific aspects of HCV infection.
Collapse
Affiliation(s)
- Catherine B Bigger
- Department of Virology and Immunology, Southwest National Primate Research Center, Southwest Foundation for Biomedical Research, 7620 NW Loop 410, San Antonio, TX 78227, USA
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Asahina Y, Izumi N, Uchihara M, Noguchi O, Nishimura Y, Inoue K, Ueda K, Tsuchiya K, Hamano K, Itakura J, Miyake S. Interferon-stimulated gene expression and hepatitis C viral dynamics during different interferon regimens. J Hepatol 2003; 39:421-7. [PMID: 12927929 DOI: 10.1016/s0168-8278(03)00287-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS To address the molecular mechanism for enhanced antiviral efficacy associated with a frequent dosing of interferon (IFN)-beta. METHODS Serum hepatitis C viral (HCV) dynamics, double-stranded RNA-activated protein kinase (PKR) mRNA and MxA mRNA levels in peripheral blood mononuclear cells (PBMC) were analyzed serially in 140 patients who were randomly assigned to a twice daily (3 MU bid) or once daily (6 MU qd) administration group. RESULTS In twice daily group, the rate of HCV decline during the second phase was 2-fold greater than in the once daily group (P=0.04). Peak PKR and MxA gene expression levels in the first phase (observed 4 h after a single administration) were 2-fold higher in the once daily group. However, the expression in the second phase was maintained at a significantly higher level in the twice daily group. Initial and peak expression levels were related to initial viral load. Basal expressions in PBMC were significantly correlated with those in the liver tissue (PKR, r=0.81; MxA, r=0.75, respectively, P<0.0001). CONCLUSIONS Our data suggest that elimination of HCV-infected cells is enhanced by twice daily dosing of IFN-beta, and that this enhanced effect is associated with a higher intracellular expression of PKR and MxA during the second phase.
Collapse
Affiliation(s)
- Yasuhiro Asahina
- Division of Gastroenterology and Hepatology, Musashino Red Cross Hospital, 1-26-1 Kyonan-cho, Musashino-shi, Tokyo 180-8610, Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Abbate I, Romano M, Longo R, Cappiello G, Lo Iacono O, Di Marco V, Paparella C, Spano A, Capobianchi MR. Endogenous levels of mRNA for IFNs and IFN-related genes in hepatic biopsies of chronic HCV-infected and non-alcoholic steatohepatitis patients. J Med Virol 2003; 70:581-7. [PMID: 12794720 DOI: 10.1002/jmv.10433] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
To investigate the intra-hepatic activation of the IFN system in patients affected by chronic HCV-infection in comparison with that observed in a non-infectious liver disease such as non-alcoholic steatohepatitis, we measured the liver steady state mRNA levels of interferon-alpha, interferon-beta and interferon-gamma as well as of IFN-related genes (IFNAR-1, STAT1alpha, PKR, 2-5 AS, IRF-1, ICE and IL-18). In HCV-infected subjects, possible correlations of these parameters with viral load and liver injury were also analyzed. Twenty-four chronic untreated HCV-infected subjects and seven patients with non-alcoholic steatohepatitis were enrolled in the study. Liver biopsies were graded according to Knodell scores. Intra-hepatic mRNA levels of IFNs and related genes were assessed by semi-quantitative RT-PCR. In comparison with non-alcoholic steatohepatitis, in HCV-infected subjects IFN-alpha and -beta mRNA levels were significantly lower, whereas IFN-gamma, IFNAR-1, STAT1alpha IRF-1, and IL-18 mRNA were upregulated. Moreover, IFN-gamma mRNA steady state levels were correlated positively with those of IFNAR-1, IRF-1, and IL-18, suggesting a coordinated induction of these genes. Although plasma viral load was correlated inversely with IL-18-specific mRNA, viral load was not related to liver injury. IFN-gamma and IRF-1 mRNA levels were correlated positively with ALT, but not with the grading or staging. Conversely, IFN-alpha and -beta mRNA levels were higher in livers with lower staging scores. These findings support the hypothesis that in chronic HCV infection there is an imbalance between an upregulated IFN-gamma system and a downregulated IFN-alpha and -beta system, probably due to a mixed effect exerted by HCV-specific and inflammatory non-specific factors.
Collapse
Affiliation(s)
- Isabella Abbate
- Microbiology and Virology Service, S. Pertini Hospital, Rome, Italy
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Di Pucchio T, Lapenta C, Santini SM, Logozzi M, Parlato S, Belardelli F. CD2+/CD14+ monocytes rapidly differentiate into CD83+ dendritic cells. Eur J Immunol 2003; 33:358-67. [PMID: 12548567 DOI: 10.1002/immu.200310010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Since denditric cells (DC) represent the main players linking innate and adaptive immunity, their prompt generation from blood cells would be instrumental for an efficient immune response to infections. Consistent with this, CD2+ monocytes were found to express the DC maturation marker CD83, along with acquisition of high antigen-presenting activity, after a surprisingly short time in culture. This rapid process is associated with expression of IFN-alpha/beta genes and secretion of low levels of pro-inflammatory cytokines. Exposure of monocytes to IFN-alpha, but not to IL-4, induced persistence of CD2+/CD83+ cells, which were fully competent in stimulating primary responses by naive T cells. These results unravel the natural pathway by which infection-induced signals rapidly transform pre-armed monocytes into active DC.
Collapse
|
20
|
Kotenko SV, Gallagher G, Baurin VV, Lewis-Antes A, Shen M, Shah NK, Langer JA, Sheikh F, Dickensheets H, Donnelly RP. IFN-lambdas mediate antiviral protection through a distinct class II cytokine receptor complex. Nat Immunol 2003; 4:69-77. [PMID: 12483210 DOI: 10.1038/ni875] [Citation(s) in RCA: 1429] [Impact Index Per Article: 68.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2002] [Accepted: 11/22/2002] [Indexed: 12/15/2022]
Abstract
We report here the identification of a ligand-receptor system that, upon engagement, leads to the establishment of an antiviral state. Three closely positioned genes on human chromosome 19 encode distinct but paralogous proteins, which we designate interferon-lambda1 (IFN-lambda1), IFN-lambda2 and IFN-lambda3 (tentatively designated as IL-29, IL-28A and IL-28B, respectively, by HUGO). The expression of IFN-lambda mRNAs was inducible by viral infection in several cell lines. We identified a distinct receptor complex that is utilized by all three IFN-lambda proteins for signaling and is composed of two subunits, a receptor designated CRF2-12 (also designated as IFN-lambdaR1) and a second subunit, CRF2-4 (also known as IL-10R2). Both receptor chains are constitutively expressed on a wide variety of human cell lines and tissues and signal through the Jak-STAT (Janus kinases-signal transducers and activators of transcription) pathway. This receptor-ligand system may contribute to antiviral or other defenses by a mechanism similar to, but independent of, type I IFNs.
Collapse
Affiliation(s)
- Sergei V Kotenko
- Department of Biochemistry and Molecular Biology, UMDNJ-New Jersey Medical School, Newark, NJ 07103, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
MacQuillan GC, de Boer WB, Platten MA, McCaul KA, Reed WD, Jeffrey GP, Allan JE. Intrahepatic MxA and PKR protein expression in chronic hepatitis C virus infection. J Med Virol 2002; 68:197-205. [PMID: 12210408 DOI: 10.1002/jmv.10182] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The therapeutic effect of interferon-alpha and ribavirin in the treatment of chronic hepatitis C viral infection is limited. To identify patient characteristics that may predict responsiveness to treatment, the intrahepatic protein expression of two directly induced IFN-alpha effector proteins, MxA and PKR, were studied. Forty liver biopsy samples from patients with a variety of chronic liver diseases were stained for MxA and PKR protein using immunohistochemical techniques. In a HCV patient cohort, 30 liver biopsies were stained for MxA and PKR protein prior to treatment with IFN-alpha and ribavirin. PKR protein expression was not upregulated in viral liver disease. In contrast, MxA protein expression was significantly upregulated in viral liver disease (P = 0.005). In chronic HCV liver disease, moderate to strong cytoplasmic expression of MxA protein was observed in hepatocytes and monocytes, indicating endogenous hepatocellular IFN-alpha pathway activation. In the HCV patient cohort treated with combination therapy, strong pre-treatment MxA hepatocyte expression was predictive of a non-response to treatment (odds ratio 9.33; P = 0.01; 95% confidence interval 1.63-53.2). This effect was independent of HCV genotype and viral load. It is concluded that pretreatment hepatocellular MxA expression may become a useful predictor of response to combination treatment with IFN-alpha and ribavirin.
Collapse
|
22
|
Kimball P, Verbeke S, Shiffman M. Proliferative suppression and class I insufficiency on peripheral blood cells from hepatitis C patients overcome by exogenous cytokines or high-dose mitogen. Clin Immunol 2002; 103:317-23. [PMID: 12173307 DOI: 10.1006/clim.2002.5217] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An abnormal T cell response to HCV viral infection is speculated to cause viral persistence, although the mechanism(s) is not understood. Using a classical in vitro test of T cell vigor, proliferative responses to PHA were determined in PBLs from 92 HCV+ individuals and 35 healthy noninfected controls. In addition, since HLA antigens modulate proliferation, surface HLA content was measured by quantitative flow cytometry. The proliferative response of cells from HCV+ individuals was lower than that of controls (SI of 91 +/- 70 vs 219 +/- 70, P < .0001). In addition, class I content was underexpressed on cells from HCV+ individuals (4540 +/- 1359 vs 13,180 +/- 5511 MESF units, P < .0001) after 5 days of PHA stimulation. Class II content was also lower than that of controls (89 +/- 17 vs 124 +/- 61 MESF units, P < .0001) after PHA stimulation. Treatment of cells from HCV+ individuals with a high dose of PHA corrected proliferative hyporesponsiveness (P < 0.01) and class I and II insufficiency (P = 0.02). Treatment with exogenous IL-2 or IFN-gamma corrected proliferative reduction (P < 0.01) but not HLA antigen content (P = ns). The results show a biochemical and functional abnormality in PBLs from HCV+ individuals, which may contribute to HCV chronicity.
Collapse
Affiliation(s)
- Pam Kimball
- Department of Surgery and Hepatology, Virginia Commonwealth University, Medical College of Virginia Campus, Richmond, Virginia, USA
| | | | | |
Collapse
|
23
|
Basu A, Meyer K, Ray RB, Ray R. Hepatitis C virus core protein modulates the interferon-induced transacting factors of Jak/Stat signaling pathway but does not affect the activation of downstream IRF-1 or 561 gene. Virology 2001; 288:379-90. [PMID: 11601909 DOI: 10.1006/viro.2001.1100] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Hepatitis C virus (HCV) has a propensity to cause chronic infection, with a low proportion of patients exhibiting a sustained response to interferon-alpha (IFNalpha) therapy. An earlier report suggested that HCV inhibits IFNalpha-induced signal transduction through the Jak/Stat pathway by preventing the formation of the transacting factor ISGF3 complex, although the effect on downstream pathway and the specific viral protein responsible for inhibition of IFNalpha-mediated signal transduction were not elucidated. HCV core protein displays a number of intriguing functional properties and has been implicated in virus-mediated pathogenesis. In this study, we have analyzed the effect of core protein upon IFNalpha- or IFNgamma-induced regulation of the Jak/Stat signaling pathway. HCV core protein expression exhibited a reduced Stat1 expression in IFN-treated mammalian cells. A gel retardation assay suggested a reduced level of formation of the transacting factors, GAF and ISGF3, in IFN-treated cells. Further studies from protein expression and RNase protection assay revealed that the reduced level of GAF or ISGF3 formation could be attributed to modulation of Stat1 protein expression, an important player for innate immunity in host defense mechanism. However, these modulatory effects did not interfere with the activation of the downstream effector genes, IRF-1 and 561, in IFN-treated cells. Stable transfectants of cells after introduction of a plasmid DNA encoding both the structural and the nonstructural proteins of HCV also exhibited a similar effect. Taken together, these results suggest that although expression of the core protein alone or with other HCV proteins modulate transacting factors of Jak/Stat signaling pathway, expression of the downstream effector genes IRF-1 and 561 remains unaffected upon IFN treatment and may contribute to host defense mechanism.
Collapse
Affiliation(s)
- A Basu
- Department of Internal Medicine, Saint Louis University, St. Louis, Missouri 63110, USA
| | | | | | | |
Collapse
|