scholarly journals Antiviral and Immunoregulatory Effects of Indoleamine-2,3-Dioxygenase in Hepatitis C Virus Infection

2015 ◽  
Vol 7 (5) ◽  
pp. 530-544 ◽  
Author(s):  
Quentin Lepiller ◽  
Eric Soulier ◽  
Qisheng Li ◽  
Mélanie Lambotin ◽  
Jochen Barths ◽  
...  
Keyword(s):  
Immune Response ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Inhibitory Effect ◽  
Hcv Infection ◽  
Antiviral Immune Response ◽  
Host Immune Responses ◽  
Indoleamine 2,3 Dioxygenase ◽  
Important Regulator ◽  
Innate Defence

In patients with hepatitis C virus (HCV) infection, enhanced activity of indoleamine-2,3-dioxygenase 1 (IDO) has been reported. IDO - a tryptophan-catabolizing enzyme - has been considered as both an innate defence mechanism and an important regulator of the immune response. The molecular mechanism of IDO induction in HCV infection and its role in the antiviral immune response remain unknown. Using primary human hepatocytes, we show that HCV infection stimulates IDO expression. IDO gene induction was transient and coincided with the expression of types I and III interferons (IFNs) and IFN-stimulated genes in HCV-infected hepatocytes. Overexpression of hepatic IDO prior to HCV infection markedly impaired HCV replication in hepatocytes, suggesting that IDO limits the spread of HCV within the liver. siRNA-mediated IDO knock-down revealed that IDO functions as an IFN-mediated anti-HCV effector. Hepatic IDO was most potently induced by IFN-γ, and ongoing HCV replication could significantly upregulate IDO expression. IRF1 (IFN-regulatory factor 1) and STAT1 (signal transducer and activator of transcription 1) regulated hepatic IDO expression. Hepatic IDO expression also had a significant inhibitory effect on CD4+ T-cell proliferation. Our data suggest that hepatic IDO plays a dual role during HCV infection by slowing down viral replication and also regulating host immune responses.

scholarly journals Adaptive Immune Response against Hepatitis C Virus

2020 ◽  
Vol 21 (16) ◽  
pp. 5644
Author(s):  
Janine Kemming ◽  
Robert Thimme ◽  
Christoph Neumann-Haefelin
Keyword(s):  
Immune Response ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Persistent Infection ◽  
Adaptive Immune Response ◽  
Hcv Infection ◽  
Viral Escape ◽  
Continuous Exposure ◽  
Adaptive Immune ◽  
Adaptive Immune Cells

A functional adaptive immune response is the major determinant for clearance of hepatitis C virus (HCV) infection. However, in the majority of patients, this response fails and persistent infection evolves. Here, we dissect the HCV-specific key players of adaptive immunity, namely B cells and T cells, and describe factors that affect infection outcome. Once chronic infection is established, continuous exposure to HCV antigens affects functionality, phenotype, transcriptional program, metabolism, and the epigenetics of the adaptive immune cells. In addition, viral escape mutations contribute to the failure of adaptive antiviral immunity. Direct-acting antivirals (DAA) can mediate HCV clearance in almost all patients with chronic HCV infection, however, defects in adaptive immune cell populations remain, only limited functional memory is obtained and reinfection of cured individuals is possible. Thus, to avoid potential reinfection and achieve global elimination of HCV infections, a prophylactic vaccine is needed. Recent vaccine trials could induce HCV-specific immunity but failed to protect from persistent infection. Thus, lessons from natural protection from persistent infection, DAA-mediated cure, and non-protective vaccination trials might lead the way to successful vaccination strategies in the future.

scholarly journals Hepatitis C virus enhances Rubicon expression, leading to autophagy inhibition and intracellular innate immune activation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yuto Shiode ◽  
Hayato Hikita ◽  
Satoshi Tanaka ◽  
Kumiko Shirai ◽  
Akira Doi ◽  
...  
Keyword(s):  
Immune Response ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Late Stage ◽  
Early Stage ◽  
Hcv Infection ◽  
Infected Cells ◽  
The Impact ◽  
Chronic Hepatitis C Patients

Abstract Autophagy, a degradation system, works to maintain cellular homeostasis. However, as the impact of Hepatitis C virus (HCV) infection on hepatocyte autophagy and its effect on HCV replication remain unclear, we examined them. HCV infection suppressed late-stage autophagy and increased Rubicon. siRNA-mediated knockdown of Rubicon promoted autophagy in HCV-infected cells. In Huh-7 cells harbouring the HCV replicon, Rubicon knockdown downregulated the expression of type 1 interferon (IFN)-related genes and upregulated HCV replication. Rubicon overexpression or administration of bafilomycin A1 or chloroquine, an inhibitor of late-stage autophagy, suppressed autophagy and activated the type 1 IFN pathway. On the other hand, Atg7 knockout suppressed early-stage autophagy and did not activate the type 1 IFN pathway. In livers of humanized liver chimeric mice, HCV infection increased Rubicon and enhanced type 1 IFN signalling. Elimination of HCV in the mice reduced the increase in Rubicon due to HCV infection. The expression levels of Rubicon and IFN-stimulated genes in chronic hepatitis C patients were higher than those in non-B, non-C hepatitis patients. HCV infection increased Rubicon and suppressed hepatocyte autophagy, leading to activation of the intracellular immune response. Rubicon induction is involved in HCV replication via activation of the intracellular immune response.

scholarly journals Control of Heterologous Hepatitis C Virus Infection in Chimpanzees Is Associated with the Quality of Vaccine-Induced Peripheral T-Helper Immune Response

2004 ◽  
Vol 78 (1) ◽  
pp. 187-196 ◽  
Author(s):  
C. Rollier ◽  
E. Depla ◽  
J. A. R. Drexhage ◽  
E. J. Verschoor ◽  
B. E. Verstrepen ◽  
...  
Keyword(s):  
Immune Response ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Interleukin 2 ◽  
Hcv Infection ◽  
T Helper ◽  
Vaccine Strategy ◽  
Ns3 Protein ◽  
Ifn Γ

ABSTRACT Prophylactic hepatitis C virus (HCV) vaccine trials with human volunteers are pending. There is an important need for immunological end points which correlate with vaccine efficacy and which do not involve invasive procedures, such as liver biopsies. By using a multicomponent DNA priming-protein boosting vaccine strategy, naïve chimpanzees were immunized against HCV structural proteins (core, E1, and E2) as well as a nonstructural (NS3) protein. Following immunization, exposure to the heterologous HCV 1b J4 subtype resulted in a peak of plasma viremia which was lower in both immunized animals. Compared to the naïve infection control and nine additional historical controls which became chronic, vaccinee 2 (Vac2) rapidly resolved the infection, while the other (Vac1) clearly controlled HCV infection. Immunization induced antibodies, peptide-specific gamma interferon (IFN-γ), protein-specific lymphoproliferative responses, IFN-γ, interleukin-2 (IL-2), and IL-4 T-helper responses in both vaccinees. However, the specificities were markedly different: Vac2 developed responses which were lower in magnitude than those of Vac1 but which were biased towards Th1-type cytokine responses for E1 and NS3. This proof-of-principle study in chimpanzees revealed that immunization with a combination of nonstructural and structural antigens elicited T-cell responses associated with an alteration of the course of infection. Our findings provide data to support the concept that the quality of the response to conserved epitopes and the specific nature of the peripheral T-helper immune response are likely pivotal factors influencing the control and clearance of HCV infection.

Amiodarone inhibits the entry and assembly steps of hepatitis C virus life cycle

2013 ◽  
Vol 125 (9) ◽  
pp. 439-448 ◽  
Author(s):  
Yuan-Lung Cheng ◽  
Keng-Hsueh Lan ◽  
Wei-Ping Lee ◽  
Szu-Han Tseng ◽  
Li-Rong Hung ◽  
...  
Keyword(s):  
Life Cycle ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Inhibitory Effect ◽  
Hcv Infection ◽  
Receptor Expression ◽  
Current Standard ◽  
Protein Activity ◽  
Entry Site

HCV (hepatitis C virus) infection affects an estimated 180 million people in the world's population. Adverse effects occur frequently with current standard treatment of interferon and ribavirin, while resistance of new direct anti-viral agents, NS3 protease inhibitors, is a major concern because of their single anti-HCV mechanism against the viral factor. New anti-viral agents are needed to resolve the problems. Amiodarone, an anti-arrhythmic drug, has recently been shown to inhibit HCV infection in vitro. The detailed mechanism has yet to be clarified. The aim of the present study was to elucidate the molecular mechanism of the inhibitory effect of amiodarone on HCV life cycle. The effect of amiodarone on HCV life cycle was investigated in Huh-7.5.1 cells with HCVcc (cell culture-derived HCV), HCVpp (HCV pseudoviral particles), sub-genomic replicons, IRES (internal ribosomal entry site)-mediated translation assay, and intracellular and extracellular infectivity assays. The administration of amiodarone appeared to inhibit HCV entry independent of genotypes, which was attributed to the down-regulation of CD81 receptor expression. The inhibitory effect of amiodarone also manifested in the HCV assembly step, via the suppression of MTP (microsomal triacylglycerol transfer protein) activity. Amiodarone revealed no effects on HCV replication and translation. With the host factor-targeting characteristics, amiodarone may be an attractive agent for the treatment of HCV infection.

scholarly journals HLA-B Alleles B*15:01 and B*15:02: Opposite Association with Hepatitis C Virus Infection in Chinese Voluntary Blood Donors

Intervirology ◽  
2015 ◽  
Vol 58 (2) ◽  
pp. 80-87 ◽  
Author(s):  
Huaping Xiong ◽  
Jieting Huang ◽  
Xia Rong ◽  
Ming Zhang ◽  
Ke Huang ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Blood Donors ◽  
Human Leukocyte ◽  
Infected Group ◽  
Hcv Infection ◽  
Hepatitis C Virus Infection ◽  
Hla Alleles ◽  
Host Immune Responses ◽  
Leukocyte Antigens

Background: Although human leukocyte antigens (HLA) have been shown in association with the outcomes of hepatitis C virus (HCV) infection among different ethnic groups, such studies remain absent in China, where the HCV prevalence is higher than the global average. Methods: In this study, 426 HCV-infected and 709 uninfected blood donors were analyzed, among whom the HLA alleles were sequenced using a high-resolution genotyping method. Results: At the 2-digit level, none of the alleles showed a statistical difference between the HCV-infected and uninfected groups. However, at the 4-digit level, the HLA-B alleles B*15:01 and B*15:02 showed an opposite association with HCV infection, i.e. B*15:01 was significantly higher in the HCV-infected group (odds ratio, OR = 1.561, p = 0.010), while B*15:02 was significantly higher in the uninfected group (OR = 0.778, p = 0.016). We also identified a higher frequency of B*13:02 in the HCV-infected group (OR = 1.515, p = 0.009) and a higher frequency of B*07:05 in the uninfected group (OR = 0.299, p = 0.001). Conclusions: The frequencies of four HLA alleles, B*07:05, B*13:02, B*15:01, and B*15:02, were found to be significantly different between the HCV-infected and uninfected blood donors in China, revealing an inverse relation of B*15:01 and B*15:02 with HCV infection. This finding suggests that the ethnic genetic variations of HLA may greatly affect the host immune responses against HCV.

scholarly journals Envelope-Specific IgG3 and IgG1 Responses Are Associated with Clearance of Acute Hepatitis C Virus Infection

Viruses ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 75 ◽  
Author(s):  
Melanie R. Walker ◽  
Auda A. Eltahla ◽  
Michael M. Mina ◽  
Hui Li ◽  
Andrew R. Lloyd ◽  
...  
Keyword(s):  
Immune Response ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Humoral Immune Response ◽  
Igg Subclasses ◽  
Hcv Infection ◽  
Disease Outcome ◽  
Antibody Activity ◽  
Acute Hepatitis C ◽  
Humoral Immune

Hepatitis C virus (HCV) can be cleared naturally in a subset of individuals. However, the asymptomatic nature of acute HCV infection makes the study of the early immune response and defining the correlates of protection challenging. Despite this, there is now strong evidence implicating the humoral immune response, specifically neutralising antibodies, in determining the clearance or chronicity outcomes of primary HCV infection. In general, immunoglobulin G (IgG) plays the major role in viral neutralisation. However, there are limited investigations of anti-HCV envelope protein 2 (E2) isotypes (IgM, IgG, IgA) and IgG subclasses (IgG1–4) in early HCV infection. In this study, using a rare cohort of 14 very recently HCV-infected individuals (4–45 days) with varying disease outcome (n = 7 clearers), the timing and potency of anti-HCV E2 isotypes and IgG subclasses were examined longitudinally, in relation to neutralising antibody activity. Clearance was associated with anti-E2 IgG, specifically IgG1 and IgG3, and appeared essential to prevent the emergence of new HCV variants and the chronic infection outcome. Interestingly, these IgG responses were accompanied by IgM antibodies and were associated with neutralising antibody activity in the subjects who cleared infection. These findings provide novel insights into the early humoral immune response characteristics associated with HCV disease outcome.

scholarly journals EFTUD2 Is a Novel Innate Immune Regulator Restricting Hepatitis C Virus Infection through the RIG-I/MDA5 Pathway

2015 ◽  
Vol 89 (13) ◽  
pp. 6608-6618 ◽  
Author(s):  
Chuanlong Zhu ◽  
Fei Xiao ◽  
Jian Hong ◽  
Kun Wang ◽  
Xiao Liu ◽  
...  
Keyword(s):  
Immune Response ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Innate Immune Response ◽  
Liver Tissue ◽  
Antiviral Effect ◽  
Innate Immune ◽  
Hcv Infection ◽  
Gene Splicing ◽  
Huh7 Cells

ABSTRACTThe elongation factor Tu GTP binding domain-containing protein 2 (EFTUD2) was identified as an anti-hepatitis C virus (HCV) host factor in our recent genome-wide small interfering RNA (siRNA) screen. In this study, we sought to further determine EFTUD2's role in HCV infection and investigate the interaction between EFTUD2 and other regulators involved in HCV innate immune (RIG-I, MDA5, TBK1, and IRF3) and JAK-STAT1 pathways. We found that HCV infection decreased the expression of EFTUD2 and the viral RNA sensors RIG-I and MDA5 in HCV-infected Huh7 and Huh7.5.1 cells and in liver tissue from in HCV-infected patients, suggesting that HCV infection downregulated EFTUD2 expression to circumvent the innate immune response. EFTUD2 inhibited HCV infection by inducing expression of the interferon (IFN)-stimulated genes (ISGs) in Huh7 cells. However, its impact on HCV infection was absent in both RIG-I knockdown Huh7 cells and RIG-I-defective Huh7.5.1 cells, indicating that the antiviral effect of EFTUD2 is dependent on RIG-I. Furthermore, EFTUD2 upregulated the expression of the RIG-I-like receptors (RLRs) RIG-I and MDA5 to enhance the innate immune response by gene splicing. Functional experiments revealed that EFTUD2-induced expression of ISGs was mediated through interaction of the EFTUD2 downstream regulators RIG-I, MDA5, TBK1, and IRF3. Interestingly, the EFTUD2-induced antiviral effect was independent of the classical IFN-induced JAK-STAT pathway. Our data demonstrate that EFTUD2 restricts HCV infection mainly through an RIG-I/MDA5-mediated, JAK-STAT-independent pathway, thereby revealing the participation of EFTUD2 as a novel innate immune regulator and suggesting a potentially targetable antiviral pathway.IMPORTANCEInnate immunity is the first line defense against HCV and determines the outcome of HCV infection. Based on a recent high-throughput whole-genome siRNA library screen revealing a network of host factors mediating antiviral effects against HCV, we identified EFTUD2 as a novel innate immune regulator against HCV in the infectious HCV cell culture model and confirmed that its expression in HCV-infected liver tissue is inversely related to HCV infection. Furthermore, we determined that EFTUD2 exerts its antiviral activity mainly through governing its downstream regulators RIG-I and MDA5 by gene splicing to activate IRF3 and induce classical ISG expression independent of the JAT-STAT signaling pathway. This study broadens our understanding of the HCV innate immune response and provides a possible new antiviral strategy targeting this novel regulator of the innate response.

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