|
1
|
Malireddi RKS, Kanneganti TD. Role of type I interferons in inflammasome activation, cell death, and disease during microbial infection. Front Cell Infect Microbiol 2013; 3:77. [PMID: 24273750 PMCID: PMC3824101 DOI: 10.3389/fcimb.2013.00077] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Accepted: 10/24/2013] [Indexed: 12/17/2022] Open
Abstract
Interferons (IFNs) were discovered over a half-century ago as antiviral factors. The role of type I IFNs has been studied in the pathogenesis of both acute and chronic microbial infections. Deregulated type I IFN production results in a damaging cascade of cell death, inflammation, and immunological host responses that can lead to tissue injury and disease progression. Here, we summarize the role of type I IFNs in the regulation of cell death and disease during different microbial infections, ranging from viruses and bacteria to fungal pathogens. Understanding the specific mechanisms driving type I IFN-mediated cell death and disease could aid in the development of targeted therapies.
Collapse
|
|
2
|
Ezelle HJ, Hassel BA. Pathologic effects of RNase-L dysregulation in immunity and proliferative control. Front Biosci (Schol Ed) 2012; 4:767-86. [PMID: 22202089 DOI: 10.2741/s298] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The endoribonuclease RNase-L is the terminal component of an RNA cleavage pathway that mediates antiviral, antiproliferative and immunomodulatory activities. Inactivation or dysregulation of RNase-L is associated with a compromised immune response and increased risk of cancer, accordingly its activity is tightly controlled and requires an allosteric activator, 2',5'-linked oligoadenylates, for enzymatic activity. The biological activities of RNase-L are a result of direct and indirect effects of RNA cleavage and microarray analyses have revealed that RNase-L impacts the gene expression program at multiple levels. The identification of RNase-L-regulated RNAs has provided insights into potential mechanisms by which it exerts antiproliferative, proapoptotic, senescence-inducing and innate immune activities. RNase-L protein interactors have been identified that serve regulatory functions and are implicated as alternate mechanisms of its biologic functions. Thus, while the molecular details are understood for only a subset of RNase-L activities, its regulation by small molecules and critical roles in host defense and as a candidate tumor suppressor make it a promising therapeutic target.
Collapse
Affiliation(s)
- Heather J Ezelle
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | | |
Collapse
|
|
3
|
Inhibition of cellular FLICE-like inhibitory protein abolishes insensitivity to interferon-α and death receptor stimulation in resistant variants of the human U937 cell line. Apoptosis 2011; 16:783-94. [DOI: 10.1007/s10495-011-0606-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
|
4
|
Huang T, Tu K, Shyr Y, Wei CC, Xie L, Li YX. The prediction of interferon treatment effects based on time series microarray gene expression profiles. J Transl Med 2008; 6:44. [PMID: 18691426 PMCID: PMC2546378 DOI: 10.1186/1479-5876-6-44] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Accepted: 08/09/2008] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The status of a disease can be reflected by specific transcriptional profiles resulting from the induction or repression activity of a number of genes. Here, we proposed a time-dependent diagnostic model to predict the treatment effects of interferon and ribavirin to HCV infected patients by using time series microarray gene expression profiles of a published study. METHODS In the published study, 33 African-American (AA) and 36 Caucasian American (CA) patients with chronic HCV genotype 1 infection received pegylated interferon and ribavirin therapy for 28 days. HG-U133A GeneChip containing 22283 probes was used to analyze the global gene expression in peripheral blood mononuclear cells (PBMC) of all the patients on day 0 (pretreatment), 1, 2, 7, 14, and 28. According to the decrease of HCV RNA levels on day 28, two categories of responses were defined: good and poor. A voting method based on Student's t test, Wilcoxon test, empirical Bayes test and significance analysis of microarray was used to identify differentially expressed genes. A time-dependent diagnostic model based on C4.5 decision tree was constructed to predict the treatment outcome. This model not only utilized the gene expression profiles before the treatment, but also during the treatment. Leave-one-out cross validation was used to evaluate the performance of the model. RESULTS The model could correctly predict all Caucasian American patients' treatment effects at very early time point. The prediction accuracy of African-American patients achieved 85.7%. In addition, thirty potential biomarkers which may play important roles in response to interferon and ribavirin were identified. CONCLUSION Our method provides a way of using time series gene expression profiling to predict the treatment effect of pegylated interferon and ribavirin therapy on HCV infected patients. Similar experimental and bioinformatical strategies may be used to improve treatment decisions for other chronic diseases.
Collapse
Affiliation(s)
- Tao Huang
- Key Laboratory of Systems Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, PR China
- Shanghai Center for Bioinformation Technology, Shanghai, 200235, PR China
| | - Kang Tu
- Key Laboratory of Systems Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, PR China
- Shanghai Center for Bioinformation Technology, Shanghai, 200235, PR China
| | - Yu Shyr
- Cancer Biostatistics Center, Vanderbilt University, Nashville, 37232, USA
| | - Chao-Chun Wei
- Shanghai Center for Bioinformation Technology, Shanghai, 200235, PR China
| | - Lu Xie
- Shanghai Center for Bioinformation Technology, Shanghai, 200235, PR China
| | - Yi-Xue Li
- Key Laboratory of Systems Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, PR China
- Shanghai Center for Bioinformation Technology, Shanghai, 200235, PR China
| |
Collapse
|
|
5
|
Pan Y, Wei W, Kang L, Wang Z, Fang J, Zhu Y, Wu J. NS5A protein of HCV enhances HBV replication and resistance to interferon response. Biochem Biophys Res Commun 2007; 359:70-5. [PMID: 17532300 DOI: 10.1016/j.bbrc.2007.05.052] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Accepted: 05/08/2007] [Indexed: 02/06/2023]
Abstract
HCV and HBV are the major causes of chronic liver diseases worldwide. Patients with both viruse's co-infection tend to develop severer liver diseases and are at high risk of liver-related death. NS5A protein of HCV plays key roles in HCV replication and inhibition of host immune responses. In this study, we described the establishment of HepG2-derived cell line that stably expresses NS5A protein and the application of a cellular system for HBV replication based on a recombinant adenovirus carrying HBV genome. Our results demonstrated that NS5A enhances the expression of S and E proteins of HBV, as well as the synthesis of viral DNA. Moreover, we showed that NS5A assists HBV to escape interferon responses. These data suggested that NS5A of HCV may employ multiple strategies contributing to the enhancement of HBV replication and interferon resistance during the co-infection of HCV and HBV.
Collapse
Affiliation(s)
- Ying Pan
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, PR China
| | | | | | | | | | | | | |
Collapse
|
|
6
|
Xiang J, McLinden JH, Chang Q, Kaufman TM, Stapleton JT. An 85-aa segment of the GB virus type C NS5A phosphoprotein inhibits HIV-1 replication in CD4+ Jurkat T cells. Proc Natl Acad Sci U S A 2006; 103:15570-5. [PMID: 17030806 PMCID: PMC1622863 DOI: 10.1073/pnas.0604728103] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
GB virus type C (GBV-C) is an apparently nonpathogenic virus that replicates in T and B lymphocytes and is a common cause of persistent human infection. Among HIV-1-infected individuals, persistent coinfection with GBV-C is associated with prolonged survival, and infection of blood mononuclear cells or CD4+ T cells with GBV-C and HIV in vitro results in significantly reduced HIV-1 replication. To date, the viral protein(s) that lead to HIV inhibition have not been identified. The GBV-C nonstructural phosphoprotein (NS5A) is predicted to have pleotropic effects on cells, including interactions with the IFN-induced dsRNA-activated protein kinase (PKR). We studied GBV-C NS5A to determine whether it is involved in inhibition of HIV replication. GBV-C NS5A protein from an isolate that was cleared by IFN therapy did not inhibit PKR, whereas NS5A from an isolate that was not cleared by IFN-inhibited PKR function in a yeast genetic system. Both of these GBV-C NS5A proteins were expressed in a CD4+ T cell line (Jurkat), and both induced a potent, dose-dependent inhibition of HIV-1 replication, thus the effect was independent of PKR inhibition. NS5A induced the release of the chemokine SDF-1 and decreased surface expression of the HIV coreceptor CXCR4, potentially explaining the HIV inhibition. Deletion mapping of the NS5A protein found that an 85-aa region between amino acids 152 and 237 inhibits HIV-1 replication. Thus, GBV-C NS5A protein alters the cellular milieu necessary for HIV-1 replication and may provide a previously undescribed therapeutic approach for anti-HIV therapy.
Collapse
Affiliation(s)
- Jinhua Xiang
- Research Service and Department of Internal Medicine, Iowa City Veterans Affairs Medical Center and University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA.
| | | | | | | | | |
Collapse
|
|
7
|
Kohashi T, Maekawa S, Sakamoto N, Kurosaki M, Watanabe H, Tanabe Y, Chen CH, Kanazawa N, Nakagawa M, Kakinuma S, Yamashiro T, Itsui Y, Koyama T, Enomoto N, Watanabe M. Site-specific mutation of the interferon sensitivity-determining region (ISDR) modulates hepatitis C virus replication. J Viral Hepat 2006; 13:582-90. [PMID: 16907844 DOI: 10.1111/j.1365-2893.2006.00739.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The number of amino acid substitutions in the interferon sensitivity-determining region (ISDR) in the nonstructural 5A (NS5A) gene of hepatitis C virus (HCV) is closely associated with the interferon (IFN) response and viral load. Several HCV replicon-based studies have reported that ISDR sequences had an influence on viral replication in vitro. However, it is unclear as to how different ISDR sequences affect HCV replication. Various clinically observed ISDR sequences were introduced into HCV replicons and their contribution to viral replication was investigated using a colony formation assay and/or a transient replication assay. A mapping study of the ISDR was performed to identify the amino acid positions that critically affect replication. While no colonies were formed in the colony formation assay using HCV replicons with few mutations (0, 1 and 3) in the ISDR, numerous colonies (>200) appeared when using constructs with six mutations. Introduction of various distinct ISDR sequences with multiple mutations resulted in replication enhancement in transient assays. A mapping study identified several specific sites in the ISDR that critically affected replication, including codon 2209 which, in patients, was closely associated with a strong response to IFN. ISDR sequences associated with a clinical IFN response and viral load modulated the replication of HCV replicons, suggesting the importance of the ISDR sequence in HCV infection.
Collapse
Affiliation(s)
- T Kohashi
- Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Yushima, Bunkyo, Tokyo, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
|
8
|
Lapinski TW, Panasiuk A, Jaroszewicz J, Kowalczuk O, Flisiak R, Rogalska M. Specific ssDNA concentration in liver tissue as an index of apoptosis in hepatitis C virus-infected patients. World J Gastroenterol 2005; 11:6130-3. [PMID: 16273639 PMCID: PMC4436629 DOI: 10.3748/wjg.v11.i39.6130] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To evaluate the activity of apoptosis in liver tissue and explore its possible association with hepatic necroinflam-mation and fibrosis as well as serum hepatitis C virus (HCV) load.
METHODS: The studied population included 50 chronic hepatitis C patients (20 women and 30 men, aged 18-66 years). HCV-RNA quantification was performed by two-step real-time quantitative RT-PCR method using the TaqMan technology (reagents of Applera Corporation firm, USA). The morphology of liver tissue was assessed descriptively and scored (necroinflammatory activity and fibrosis). The early apoptosis activity in liver tissue was examined by ssDNA apoptosis ELISA kit, (Chemicon, Germany).
RESULTS: The correlation between apoptosis and fibrosis in liver tissue was observed. High intensification of apoptosis was proportional to the increase of fibrosis (ssDNA: 16.65×10-5 mg/g; 12.71×10-5 mg/g), however, this difference was not statistically significant (P>0.05). Activity of apoptosis in the liver tissue, expressed by ssDNA concentration did not depend on hepatic necroinflammatory changes, HCV-RNA viral load, ALT, and AST activity as well as prothrombin time and INR index.
CONCLUSION: Fibrosis in the tissue is closely associated with early apoptosis in HCV-infected patients.
Collapse
Affiliation(s)
- Tadeusz-Wojciech Lapinski
- Department of Infectious Diseases, Medical University of Bialystok, Bialystok 15-540, Zurawia str, 14, Poland.
| | | | | | | | | | | |
Collapse
|
|
9
|
Huang Y, Erdmann N, Zhao J, Zheng J. The signaling and apoptotic effects of TNF-related apoptosis-inducing ligand in HIV-1 associated dementia. Neurotox Res 2005; 8:135-48. [PMID: 16260391 DOI: 10.1007/bf03033825] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
HIV-1 Associated Dementia (HAD) develops during progressive HIV-1 infection and is characterized by cognitive impairments, behavioral disorders and potential progressive motor abnormality. Abnormal inflammation within the central nervous system (CNS), activation of macrophage/microglia and involvement of proinflammatory cytokines have been suggested as primary factors in the pathogenesis of HAD. Impairment of neuronal function and neuronal cell death are believed to be the end pathophysiological result of HAD. TNF-related apoptosis-inducing ligand (TRAIL), a member of the TNF family of cytokines, was suggested to participate in apoptotic cell death during HAD. As a death ligand, TRAIL was originally thought to target only tumor cells. TRAIL is not typically present in CNS; however, emerging data show that TRAIL can be induced by immune stimuli on macrophage and microglia, major disease effector cells during HAD. Upregulated TRAIL may then cause neuronal apoptosis through direct interaction with TRAIL receptors on neurons or through macrophage death-mediated release of neurotoxins. In this review, we summarize the pivotal role of TRAIL in HAD and TRAIL-initiated intracellular death cascades that culminate in neuronal apoptosis as observed in HAD.
Collapse
Affiliation(s)
- Y Huang
- The Laboratory of Neurotoxicology at the Center for Neurovirology & Neurodegenerative Disorders, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | | | | | | |
Collapse
|
|
10
|
Xiang J, Martinez-Smith C, Gale M, Chang Q, Labrecque DR, Schmidt WN, Stapleton JT. GB virus type C NS5A sequence polymorphisms: association with interferon susceptibility and inhibition of PKR-mediated eIF2alpha phosphorylation. J Interferon Cytokine Res 2005; 25:261-70. [PMID: 15871663 DOI: 10.1089/jir.2005.25.261] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
GB virus type C (GBV-C) causes persistent infection in humans, although the mechanism by which the virus avoids clearance by the host is unknown. To determine if amino acid polymorphisms in the GB virus type C (GBV-C) NS5A and E2 proteins alter response to interferon (IFN) therapy, we studied the sequence of GBVC NS5A and E2 obtained from people receiving IFN therapy. In addition, we expressed recombinant GBVC NS5A protein to determine if it interferes with RNA-activated protein kinase (PKR) function in vitro. GBVC NS5A amplified from a person whose virus was cleared by IFN therapy (IFN sensitive) demonstrated unique amino acid changes occurring in the region that aligns with the hepatitis C virus (HCV) IFN sensitivity-determining region (ISDR) compared with NS5A sequences from individuals who did not clear GBV-C (IFN resistant). There were no differences in the E2 sequences obtained from IFN-sensitive and IFN-resistant isolates. Using a yeast genetic system, IFN-resistant NS5A inhibited PKR-mediated phosphorylation of eukaryotic initiation factor 2alpha (eIF2alpha) in yeast, whereas IFN-sensitive NS5A did not inhibit PKR function. GBV-C NS5A amino acid polymorphisms appear to be involved in response to IFN therapy, and IFN-resistant GBV-C NS5A inhibited PKR-mediated eIF2alpha phosphorylation in a yeast genetic system, suggesting a mechanism by which GBV-C may evade clearance by naturally occurring host antiviral responses.
Collapse
MESH Headings
- Amino Acid Sequence
- Base Sequence
- DNA, Viral/genetics
- Drug Resistance, Viral/genetics
- Eukaryotic Initiation Factor-2/metabolism
- Flaviviridae Infections/complications
- Flaviviridae Infections/drug therapy
- Flaviviridae Infections/virology
- GB virus C/drug effects
- GB virus C/genetics
- GB virus C/pathogenicity
- GB virus C/physiology
- Gene Expression
- Hepatitis C, Chronic/complications
- Hepatitis C, Chronic/drug therapy
- Hepatitis C, Chronic/virology
- Hepatitis, Viral, Human/complications
- Hepatitis, Viral, Human/drug therapy
- Hepatitis, Viral, Human/virology
- Humans
- In Vitro Techniques
- Interferon Type I/pharmacology
- Molecular Sequence Data
- Phosphorylation
- Polymorphism, Genetic
- Recombinant Proteins
- Sequence Homology, Amino Acid
- Two-Hybrid System Techniques
- Viral Nonstructural Proteins/genetics
- Viral Nonstructural Proteins/physiology
- eIF-2 Kinase/antagonists & inhibitors
Collapse
Affiliation(s)
- Jinhua Xiang
- Department of Internal Medicine and Research, Iowa City VA Medical Center and University of Iowa, Iowa City, IA 52242, USA
| | | | | | | | | | | | | |
Collapse
|
|
11
|
Hnatyszyn HJ. Chronic Hepatitis C and Genotyping: The Clinical Significance of Determining HCV Genotypes. Antivir Ther 2005. [DOI: 10.1177/135965350501000118] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chronic hepatitis C, attributed to infection with hepatitis C virus (HCV), is a global health problem. The overall prevalence of viral hepatitis worldwide is estimated to be 3–5% with over 175 million people infected with HCV. Clinically, HCV can establish a persistent, chronic infection contributing to progressive liver disease, including cirrhosis and hepatocellular carcinoma (HCC), requiring intensive treatment regimens, possible liver transplantation and long-term care. Due to the chronic nature of HCV infection and the tremendous burden on healthcare resources, clinicians and laboratorians have looked for key epidemiological, pathological and viral characteristics that may provide insight into disease progression, severity and response to therapy to permit the administration of effective therapeutic regimens as well as long-term management of infected individuals. Determination of viral genotype has been identified as one parameter that could provide direction in the clinical management of patients with chronic HCV infections. The following review provides background on determination of HCV genotypes and the relevance of viral genome characterization in the current clinical setting.
Collapse
Affiliation(s)
- H James Hnatyszyn
- Bayer Institute for Clinical Investigation (BICI), Bayer HealthCare – Diagnostics Division, Berkeley, CA, USA
| |
Collapse
|
|
12
|
Lapinski TW, Kowalczuk O, Prokopowicz D, Chyczewski L. Serum concentration of sFas and sFasL in healthy HBsAg carriers, chronic viral hepatitis B and C patients. World J Gastroenterol 2004; 10:3650-3. [PMID: 15534924 PMCID: PMC4612010 DOI: 10.3748/wjg.v10.i24.3650] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM: To estimate the amount of apoptosis among healthy HBsAg carriers, patients with chronic HBV infection treated with lamivudine and patients with chronic HCV infection treated with interferon alpha and ribavirin. Activity of apoptosis was evaluated by serum sFas/sFasL concentration measurement. Moreover dependence between apoptosis and HBV-DNA or HCV-RNA levels was studied.
METHODS: Eighty-six persons were included into study: 34 healthy HBsAg carriers, 33 patients with chronic HBV infection and 19 patients with chronic HCV infection. Serum levels of sFas/sFasL were measured by ELISA assay. HBV-DNA and HCV-RNA were measured by RT-PCR assay. Levels of sFas/sFasL were determined before and 2 and 12 wk after therapy in patients with chronic hepatitis B and C infection. HBV-DNA or HCV-RNA was detected before treatment and 6 mo after treatment.
RESULTS: Twenty-four (71%) healthy HBsAg carriers showed HBV-DNA over 105/mL, which was comparable to the patients with chronic hepatitis B. Independently from HBV-DNA levels, the concentration of sFas among healthy HBsAg carriers was comparable to healthy persons. Among patients with chronic hepatitis B and C, the concentration of sFas was significantly higher in comparison to healthy HBsAg carriers and healthy persons. In chronic hepatitis B patients the concentration of sFas was decreased during lamivudine treatment. Among chronic hepatitis C patients the concentration of sFas was increased during IFN alpha and ribavirin treatment. sFasL was not detected in control group. Furthermore sFasL occurred more frequently in chronic hepatitis C patients in comparison to chronic hepatitis B patients.
CONCLUSION: There are no correlations between apoptosis and HBV-DNA levels. However ther is an association between apoptosis and activity of inflammation in patients with chronic HBV infection. Apoptosis can be increased in patients with chronic hepatitis C by effective treatment which may be a result of apoptosis stimulation by IFN-α.
Collapse
Affiliation(s)
- Tadeusz-Wojciech Lapinski
- Department of Infectious Diseases, Medical University of Bialystok, 15-540 Bialystok, Zurawia str., 14, Poland.
| | | | | | | |
Collapse
|
|
13
|
Abstract
The non-structural 5A (NS5A) protein of hepatitis C virus (HCV) has been the subject of intensive research over the last decade. It is generally accepted that NS5A is a pleiotropic protein with key roles in both viral RNA replication and modulation of the physiology of the host cell. Our understanding of the role of NS5A in the virus life cycle has been hampered by the lack of a robust in vitro system for the study of HCV replication, although the recent development of the subgenomic replicon has at least allowed us to begin to dissect the involvement of NS5A in the process of viral RNA replication. Early studies into the effects of NS5A on cell physiology relied on expression of NS5A either alone or in the context of other non-structural proteins; the advent of the replicon system has allowed the extrapolation of these studies to a more physiologically relevant cellular context. Despite recent progress, this field is controversial, and there is much work to be accomplished before we fully understand the many functions of this protein. In this article, the current state of our knowledge of NS5A, discussing in detail its direct involvement in virus replication, together with its role in modulating the cellular environment to favour virus replication and persistence, are reviewed. The effects of NS5A on interferon signalling, and the regulation of cell growth and apoptosis are highlighted, demonstrating that this protein is indeed of critical importance for HCV and is worthy of further investigation.
Collapse
Affiliation(s)
- Andrew Macdonald
- School of Biochemistry & Microbiology and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Mark Harris
- School of Biochemistry & Microbiology and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| |
Collapse
|
|
14
|
Abstract
Interferon-inducible, double-stranded RNA-dependent protein kinase PKR is well known as an early cellular responder to viral infection. Activation of PKR has been associated with a number of downstream cell stress and cell death events, including a generalized shutdown of protein translation, activation of caspase-8, participation in JNK and p38 MAPK pathways, activation of NF-kappaB, etc. Recently, the activation of PKR has also been described in several neurodegenerative diseases, including Huntington disease, Alzheimer disease, and amyotrophic lateral sclerosis. Although the relationship between PKR and these diseases is still unclear, the overlap between known functions of PKR and biochemical events that occur in these neuropathologies are discussed here.
Collapse
Affiliation(s)
- Alyson L Peel
- The Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA. www.buckinstitute.org
| |
Collapse
|
|
15
|
Seet BT, Johnston JB, Brunetti CR, Barrett JW, Everett H, Cameron C, Sypula J, Nazarian SH, Lucas A, McFadden G. Poxviruses and immune evasion. Annu Rev Immunol 2003; 21:377-423. [PMID: 12543935 DOI: 10.1146/annurev.immunol.21.120601.141049] [Citation(s) in RCA: 488] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Large DNA viruses defend against hostile assault executed by the host immune system by producing an array of gene products that systematically sabotage key components of the inflammatory response. Poxviruses target many of the primary mediators of innate immunity including interferons, tumor necrosis factors, interleukins, complement, and chemokines. Poxviruses also manipulate a variety of intracellular signal transduction pathways such as the apoptotic response. Many of the poxvirus genes that disrupt these pathways have been hijacked directly from the host immune system, while others have demonstrated no clear resemblance to any known host genes. Nonetheless, the immunological targets and the diversity of strategies used by poxviruses to disrupt these host pathways have provided important insights into diverse aspects of immunology, virology, and inflammation. Furthermore, because of their anti-inflammatory nature, many of these poxvirus proteins hold promise as potential therapeutic agents for acute or chronic inflammatory conditions.
Collapse
Affiliation(s)
- Bruce T Seet
- Department of Microbiology and Immunology, University of Western Ontario, London, Canada.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
|
16
|
Abstract
The interferons (IFNs), in addition to their well-known antiviral activities, have important roles in the control of cell proliferation and are effective agents for the treatment of a limited number of malignant diseases. IFNs not only regulate cell growth and division but also influence cell survival through their effects on apoptosis. This review describes the current state of knowledge about the mechanisms of action of these cytokines on the apoptotic machinery, with particular emphasis on the synergism that exists between the IFNs and other proapoptotic agents, such as members of the tumor necrosis factor (TNF) family. The review also discusses the physiologic and clinical implications of the effects of the IFNs on apoptosis for regulation of viral infection and tumor growth.
Collapse
Affiliation(s)
- Michael J Clemens
- Translational Control Group, Department of Basic Medical Sciences, St. George's Hospital Medical School, London SW17 0RE, UK.
| |
Collapse
|
|
17
|
Abstract
In summary, HCV-cell interactions include those directly involved with the HCV life cycle such as virus attachment, entry, and replication. Included within this broad area of research are the interactions of HCV proteins with the IFN system, cytokine and chemokine pathways such as IL-8, and various other cellular proteins and pathways. The plethora of contradictory and sometimes confusing accessory HCV-host interactions defies precise predictions of their role in HCV biology. It is clear that these virus-cell interactions affect HCV replication, antiviral resistance, persistence, and pathogenesis. Because HCV-host interactions are initiated immediately on infection, they are operative during acute HCV infection, whereby HCV interacts with innate cellular antiviral and immune systems. The magnitude and duration of these HCV-host interactions therefore may influence the development of acquired immunity. Because HCV exists as a quasispecies in all infected individuals, heterogeneity in biological responses to HCV-host interactions is predicted, revealing opportunities for the development of various genotypic and phenotypic prognostic indicators. With the model systems in place, these hypotheses can be tested. The challenge for the future is to determine if there is a hierarchical importance to these interactions, to delineate how these virus-cell interactions affect the patient infected with HCV, and to determine whether any of these interactions represents a target for therapeutic intervention.
Collapse
Affiliation(s)
- Stephen J Polyak
- Department of Laboratory Medicine, University of Washington, Box 359690, 325 9th Avenue, Seattle, WA 98104-2499, USA.
| |
Collapse
|
|
18
|
Ezelle HJ, Markovic D, Barber GN. Generation of hepatitis C virus-like particles by use of a recombinant vesicular stomatitis virus vector. J Virol 2002; 76:12325-34. [PMID: 12414973 PMCID: PMC136870 DOI: 10.1128/jvi.76.23.12325-12334.2002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Hepatitis C virus (HCV), a major etiologic agent of hepatocellular carcinoma, presently infects approximately 400 million people worldwide, making the development of protective measures against HCV infection a key objective. Here we have generated a recombinant vesicular stomatitis virus (VSV), which expresses the HCV structural proteins, by inserting the contiguous Core, E1, and E2 coding region of HCV into the VSV genome. Recombinant VSV expressing HCV Core, E1, and E2 (VSV-HCV-C/E1/E2) grew to high titers in vitro and efficiently expressed the incorporated HCV gene product, which became fully processed into the individual HCV structural proteins. Biochemical and biophysical analysis indicated that the HCV Core, E1, and E2 proteins assembled to form HCV-like particles (HCV-LPs) possessing properties similar to the ultrastructural properties of HCV virions. Mice immunized with VSV-HCV-C/E1/E2 generated cell-mediated immune responses to all of the HCV structural proteins, and humoral responses, particularly to E2, were also readily evident. Our data collectively indicate that engineered VSVs expressing HCV Core, E1, and E2 and/or HCV-LPs represent useful tools in vaccine and immunotherapeutic strategies designed to address HCV infection.
Collapse
Affiliation(s)
- Heather J Ezelle
- Department of Microbiology and Immunology and Sylvester Comprehensive Cancer Center, University of Miami School of Medicine, Miami, Florida 33136, USA
| | | | | |
Collapse
|
|
19
|
He Y, Katze MG. To interfere and to anti-interfere: the interplay between hepatitis C virus and interferon. Viral Immunol 2002; 15:95-119. [PMID: 11952150 DOI: 10.1089/088282402317340260] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
As popular strategies used by numerous viruses, interception of interferon (IFN) signaling and inhibition of IFN-induced antiviral functions allow viruses to evade the host immune response and set up successful infections. Hepatitis C virus (HCV), the leading cause of chronic liver disease worldwide and a major public health hazard, causes persistent infection in the majority of infected individuals. IFN-based therapies, currently the only ones available for HCV infection, have been unable to eliminate viral infection in the majority of patients, and many studies suggest that HCV possesses mechanisms to antagonize the IFN-induced antiviral response. Multiple viral, host, and IFN-associated factors have been implicated in the interplay between HCV and IFN. Two viral proteins, NS5A and E2, became the focus of much attention and extensive study because of their abilities to inhibit IFN-induced, double-stranded RNA-activated protein kinase (PKR), a major mediator of the IFN-induced biologic response, and to perturb the IFN signaling pathway. In this review, we discuss the significance of the interferon sensitivity determining region (ISDR) within NS5A, which has been the subject of intense debates. In addition, we discuss the potential mechanisms by which NS5A interferes with IFN signaling and the current working models. Further understanding of the molecular mechanisms underlying the interaction between HCV and IFN will likely facilitate improvement of current IFN-based therapies and development of novel treatments for the HCV pandemic. Future HCV research will benefit from both the development of efficient, convenient model systems for viral propagation, and the utilization of high throughput, genomic-scale approaches.
Collapse
Affiliation(s)
- Yupeng He
- Department of Microbiology, School of Medicine, University of Washington, 98195, USA
| | | |
Collapse
|
|
20
|
Khabar KSA, Polyak SJ. Hepatitis C virus-host interactions: the NS5A protein and the interferon/chemokine systems. J Interferon Cytokine Res 2002; 22:1005-12. [PMID: 12433279 DOI: 10.1089/107999002760624224] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The interactions that occur between viral proteins and host factors, such as cellular proteins and signal transduction machinery, have a significant influence on the replication, persistence, and pathogenesis of all viruses. This is exemplified by hepatitis C virus (HCV), which infects an estimated 3% of the world's population and is a significant cause of liver disease. HCV-host interactions also affect the outcome of interferon (IFN) antiviral therapy, which is effective only in certain patients. In this review, we focus on the HCV nonstructural 5A (NS5A) protein, a model for diverse virus-host interactions, and highlight the interaction of viruses, including HCV, with the chemokine system.
Collapse
Affiliation(s)
- Khalid S A Khabar
- Department of Biological and Medical Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia
| | | |
Collapse
|
|
21
|
Squadrito G, Raffa G, Restuccia T, Pollicino T, Brancatelli S, Raimondo G. Is investigation of hepatitis C virus NS5A gene heterogeneity a tool for predicting long-lasting response to interferon therapy in patients with HCV-1b chronic hepatitis? J Viral Hepat 2002; 9:360-369. [PMID: 12225331 DOI: 10.1046/j.1365-2893.2002.00379.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Nonstructural protein 5A (NS5A) of the hepatitis C virus (HCV) may repress the interferon (IFN)-induced protein kinase R (PKR). High variability of different regions in the carboxy-terminal half of NS5A implicated in the interaction with PKR (particularly the interferon sensitivity determining region (ISDR)) may be a predictor of response to IFN in patients infected with genotype 1b of HCV. We examined pretreatment serum samples from 17 HCV-1b infected patients included in the same schedule of IFN therapy. Seven patients were a rare series of sustained responders (SR) with a post-treatment follow-up of 5-7 years, while ten were nonresponders (NR). The carboxy-terminal half of the NS5A gene was amplified and directly sequenced in all 17 cases. In addition, the entire NS5A gene and the part of the HCV E2 gene coding for the hypervariable region 1 (HVR1) were amplified, cloned and sequenced in six cases (three NR and three SR). No difference in number and distribution of amino acid mutations was observed between isolates from SR and NR in any portion of the protein, including the ISDR region. Analysis of full length NS5A confirmed no difference between the two groups. The NS5A gene sequence was different among the six cases cloned although it appeared to be conserved in each individual patient independently of the quasispecies complexity evaluated through HVR1 examination. These data indicate that pretreatment analysis of theNS5A genomic variability has no value in predicting long-lasting response to IFN therapy in HCV-1b-infected patients, and that the HCV NS5A gene has high quasispecies homology.
Collapse
Affiliation(s)
- G Squadrito
- Dipartimento di Medicina Interna, Policlinico Universitario, Messina, Italy
| | | | | | | | | | | |
Collapse
|
|
22
|
Abstract
All known apoptosis modulators in poxviruses have been shown to function as inhibitors. The mechanistic classes of these poxvirus-encoded inhibitors are quite diverse, and indicate that a wide variety of distinct host proteins in cellular apoptotic pathways have been targeted for inhibition by individual poxviruses.
Collapse
Affiliation(s)
- Helen Everett
- Department of Biochemistry, University of Alberta, 4-63 Medical Sciences Building, Edmonton, T6G 2H7, Alberta, Canada.
| | | |
Collapse
|
|
23
|
Abstract
Many viruses have as part of their arsenal the ability to modulate the apoptotic pathways of the host. It is counter-intuitive that such simple organisms would be efficient at regulating this the most crucial pathway within the host, given the relative complexity of the host cells. Yet, viruses have the potential to initiate or stay the onset of programmed cell death through the manipulation of a variety of key apoptotic proteins. It is the intention of this review to provide an overview of viral gene products that are able to promote or inhibit apoptotic death of the host cell and to discuss their mechanisms of action. It is not until recently that the depth at which viruses exploit the apoptotic pathways of their host has been seen. This understanding may provide a great opportunity for future therapeutic ventures.
Collapse
Affiliation(s)
- Stewart Hay
- The Fiona Elsey Cancer Research Laboratory, Cancer Research Centre, School of Science, University of Ballarat, St John of God Hospital, 1002 Mair Street, Ballarat, Victoria 3350, Australia1
| | - George Kannourakis
- The Fiona Elsey Cancer Research Laboratory, Cancer Research Centre, School of Science, University of Ballarat, St John of God Hospital, 1002 Mair Street, Ballarat, Victoria 3350, Australia1
| |
Collapse
|
|
24
|
Shi ST, Polyak SJ, Tu H, Taylor DR, Gretch DR, Lai MMC. Hepatitis C virus NS5A colocalizes with the core protein on lipid droplets and interacts with apolipoproteins. Virology 2002; 292:198-210. [PMID: 11878923 DOI: 10.1006/viro.2001.1225] [Citation(s) in RCA: 239] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The nonstructural protein 5A (NS5A) of the hepatitis C virus (HCV) has been shown to interact with a variety of cellular proteins and implicated in the regulation of cell growth, interferon resistance, and other cellular signaling pathways, but the role of NS5A in HCV pathogenesis has not been firmly established. To further characterize this multifunctional protein, we instigated the studies of the subcellular localization of NS5A in a hepatoma cell line. NS5A was localized to the perinuclear membrane structures, including the endoplasmic reticulum (ER) and the Golgi apparatus, by immunofluorescence staining and confocal microscopy. In addition, it was also associated with the surface of cytoplasmic globular structures when expressed alone or as a part of the NS3-5B polyprotein. Oil red O staining revealed that these globular structures were lipid droplets, where the HCV core protein was also localized. The association of NS5A with intracellular membrane was further confirmed by membrane flotation analysis. To determine whether NS5A interacts with any cellular lipid-binding protein, we performed yeast two-hybrid screening in both HepG2 and human liver cDNA libraries. Apolipoprotein A1 (apoA1), one of the protein components of high-density lipoprotein (HDL) particles, was identified by two independent screening processes. The interaction between NS5A and apoA1 was confirmed by both in vitro pull-down and in vivo coimmunoprecipitation experiments. Immunofluorescence staining revealed a significant colocalization of NS5A and apoA1 in the Golgi apparatus. Our results established an association of NS5A with lipid droplets and apoA1, suggesting that NS5A, together with the core protein, may play a role in the pathogenesis of the derangement of lipid metabolism, contributing to liver steatosis commonly observed in hepatitis C.
Collapse
Affiliation(s)
- Stephanie T Shi
- Department of Molecular Microbiology and Immunology, University of Southern California, Keck School of Medicine, Los Angeles, California 90033, USA
| | | | | | | | | | | |
Collapse
|
|
25
|
Tan SL, Katze MG. How hepatitis C virus counteracts the interferon response: the jury is still out on NS5A. Virology 2001; 284:1-12. [PMID: 11352662 DOI: 10.1006/viro.2001.0885] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Interferons (IFNs) induce an antiviral state in the cell through complex and indirect mechanisms, which culminate in a direct inhibition of viral replication and stimulation of the host adaptive responses. Viruses often counteract with elaborate strategies to interfere with the induction as well as action of IFN effector molecules. This evolutionary battle between viruses and IFN components is a subject of intense research aimed at understanding the immunopathogenesis of viruses and the molecular basis of IFN signaling and action. In the case with hepatitis C virus (HCV), this may have profound implications for the therapeutic use of recombinant IFN in treating chronic hepatitis C. Depending on the subtype of HCV, current IFN-based treatment regimens are effective for only a small subset of chronic hepatitis C patients. Thus, one of the Holy Grails in HCV research is to understand the mechanisms by which the virus may evade IFN antiviral surveillance and establish persistent infection, which may eventually provide insights into new avenues for better antiviral therapy. Despite the lack of an efficient tissue culture system and an appropriate animal model for HCV infection, several mechanisms have been proposed based on clinical studies and in vitro experiments. This minireview focuses on the HCV NS5A nonstructural protein, which is implicated in playing a role in HCV tolerance to IFN treatment, possibly in part through its ability to inhibit the cellular IFN-induced PKR protein kinase.
Collapse
Affiliation(s)
- S L Tan
- Infectious Diseases Research, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
| | | |
Collapse
|