• Korean Journal of Microbiology
• /
• v.50 no.2
• /
• pp.169-172
• /
• 2014

Recently, Hepatitis C virus (HCV) replication system has been established using human hepatoma cells (huh cell) and a variety of HCV clones. In this study, we established an infectious HCV replication system using huh7.5 cells and J6/JFH1 clone (genotype 2a). In addition, we investigated the antigen presentation capability of HCV-infected huh7.5 cells to HCV-specific T cells. Interestingly, HCV-infected huh7.5 cells were not capable of activating HCV-specific T cells. However, huh7.5 cells stimulated by exogenous HCV peptide were able to activate HCV-specific T cells, which was shown to produce TNF-${\alpha}$ and IFN-${\gamma}$. We further examined if HCV infection has an inhibitory effect on the expression of MHC class I molecule of huh7.5 cells. We found that HCV infection did not change the expression level of MHC class I molecule on huh7.5 cells.

• Korean Journal of Microbiology
• /
• v.47 no.4
• /
• pp.342-347
• /
• 2011

T cells play a key role in viral infection. However, in patients with chronic hepatitis C virus (HCV) infection, HCV-specific T cells are dysfunctional and impaired in the liver, which is the primary site for HCV replication. There are multiple potential mechanisms for HCV-specific T cell dysfunction including induction of immune inhibitory pathways (program death-1; PD-1, cytotoxic t lymphocyte associated antigen-4; CTLA-4) and immune tolerance induced specific for the liver. However, the interaction between hepatocytes and HCV-specific CD8 T cells has not clearly established. In this study, we confirmed huh (human hepatoma) 7.5 cells expressing HLA (human leukocyte antigen) A2 presented antigen to activate HCV-specific CD8 T cells in HLA A2-restricted manner and expression of PD-L (program death ligand) 1 on huh7.5 cells reduced HCV-specific CD8 T cell activation, suggesting an immune modulatory activity. Loss of HCV-specific tetramer responses following antigenic stimulation correlated with increased caspase-3 activity. In addition, PD-L1 on huh7.5 cells rescued HCV-specific CD8 T cells from apoptosis. Our results suggest that the interaction between PD-L1 and PD-1 can recover the function of HCV-specific CD8 T cells in the liver, which could be applied in therapy of HCV chronic infection.

• IMMUNE NETWORK
• /
• v.10 no.4
• /
• pp.120-125
• /
• 2010

Dysfunction of the virus-specific T cells is a cardinal feature in chronic persistent viral infections such as one caused by hepatitis C virus (HCV). In chronic HCV infection, virus-specific dysfunctional CD8 T cells often overexpress various inhibitory receptors. Programmed cell death 1 (PD-1) was the first among these inhibitory receptors that were identified to be overexpressed in functionally impaired T cells. The roles of other inhibitory receptors such as cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) and T cell immunoglobulin and mucin domain-containing molecule 3 (Tim-3) have also been demonstrated in T-cell dysfunctions that occur in chronic HCV patients. Blocking these inhibitory receptors in vitro restores the functions of HCV-specific CD8 T cells and allows enhanced proliferation, cytolytic activity and cytokine production. Therefore, the blockade of the inhibitory receptors is considered as a novel strategy for the treatment of chronic HCV infection.

• Korean Journal of Microbiology
• /
• v.49 no.3
• /
• pp.221-227
• /
• 2013

Human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) cause viral infections that lead to chronic diseases. When they invade human body, virus specific T cells play an important role in antiviral effector functions including killing virus-infected cells and helping B cells to produce specific antibodies against viral proteins. The antiviral activity of T cells is usually affected by immune-regulatory factors that express on surface of T cells. Recently, many researchers have investigated the relationship between effector functions of virus specific T cells and characteristics of immune regulatory factors (e.g., CD28, CD25, CD45RO, FoxP3, PD-1, CTLA-4). In particular, Immune inhibitory molecules such as forkhead box P3 (FoxP3), programmed death-1 (PD-1), and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) are associated with T-cell dysfunction. They are shown to be up-regulated in chronic viral diseases such as hepatitis B, hepatitis C or human immunodeficiency virus infection. Therefore, the positive correlation between viral persistence and expression of immune regulatory factors (FoxP3, PD-1, and CTLA-4) has been suggested. In this review, the roles of immune regulatory factors FoxP3, PD-1, and CTLA-4 were discussed in chronic viral diseases such as HIV, HBV, or HCV.

• Animal cells and systems
• /
• v.3 no.3
• /
• pp.337-341
• /
• 1999

Hepatitis C virus (HCV) is a positive strand RNA virus of the Flaviviridae family and the major cause of post-transfusion non-A, non-B hepatitis. Vaccine development for HCV is essential but has been slowed by poor understanding of the type of immunity that naturally terminates HCV infection. The DNA-based immunization technique offers the potential advantage of including cellular immune responses against conserved internal proteins of a virus, as well as the generation of antibodies to viral surface proteins. Here, we demonstrate that cell lines expressing the HCV core and/or NS3 proteins can induce a specific CTL response in mice, and these results suggest a possibility that the HCV core and NS3 DNA can be used to induce CTL activity against the antigen in mice and can be further developed as a therapeutic and preventive DNA vaccine.

• Journal of Life Science
• /
• v.13 no.5
• /
• pp.551-558
• /
• 2003

Hepatitis C Virus (HCV) is associated with a severe liver disease and increased frequency in the development of hepatocellular carcinoma. Overexpression of HCV core protein is known to transform fibroblast cells. Phospholipase D (PLD) activity is commonly elevated in response to mitogenic signals, and PLD has been also reported to be overexpressed and hyperactivated in some human cancer. The aim of this study was to understand how PLD can be regulated in HCV core protein-transformed NIH3T3 mouse fibroblast cells. We observed that in unstimulated state, basal PLD activity was higher in NIH3T3 cells overexpressing HCV core protein than in vector-transfected cells. Although expression of PLD and protein kinase C (PKC) in core protein-transformed cells was similar with that of control cells, phorbol 12-myristate 13-acetate (PMA), which is known to activate PKC, stimulated significantly PLD activity in core protein-transformed cells, compared with that of the control cells. PLD activity assay using PKC isozyme-specific inhibitor, and PKC translocation experiment showed that PKC-$\delta$ was mainly involved in the PMA-induced PLD activation in the core-transformed cells. Taken together, these results suggest that PLD might be implicated in core protein-induced transformation.