The goal of this project is to understand why HCV infection fails to induce a strong cell mediated immune responsible to eliminate the virus. Here we propose to investigate relevant immune parameters in a small animal model and in vitro. Because HCV is not infectious in mice, models making use of HCV transgenic mice, animals infected with adenovirus constructs coding for an HCV gene and in vitro culture systems will be used. In the previous granting period we have established experimental approaches to study immune responses in the liver with the aim to elucidate how HCV gene modulate these responses Because the HCV core to date is the only HCV coded protein with putative immunoregulatory functions we are focusing on the immunoregulatory effects of this protein. The HCV core has been reported to exert a multitude of effects, namely on TNFalpha and Fas signaling the induction of cytotoxic T cells and the induction of IL-12. The availability of HCV core transgenic mice and adenoviral vectors expressing the HCV core, both generated in the previous granting period make it possible to investigate whether the core period has immunoregulatory effects. Specifically we will examine how the HCV core modulates signaling through TNF receptors. We will examine what are the effects of the core on the induction of cytotoxic T cells in vivo and in vitro. Given the notion that the core has effects on IL-12 we will explore its influence on the maturation and function of antigen presenting cells in the liver. Because there is increasing evidence for an important role of NK cells in viral liver infections we will elucidate whether the core has effects on the function of these cells during a virus infection.

Project Start
2002-09-01
Project End
2003-06-30
Budget Start
Budget End
Support Year
7
Fiscal Year
2002
Total Cost
Indirect Cost
Name
University of Southern California
Department
Type
DUNS #
041544081
City
Los Angeles
State
CA
Country
United States
Zip Code
90033
Liu, Helene Minyi; Aizaki, Hideki; Machida, Keigo et al. (2012) Hepatitis C virus translation preferentially depends on active RNA replication. PLoS One 7:e43600
Machida, Keigo; McNamara, George; Cheng, Kevin T-H et al. (2010) Hepatitis C virus inhibits DNA damage repair through reactive oxygen and nitrogen species and by interfering with the ATM-NBS1/Mre11/Rad50 DNA repair pathway in monocytes and hepatocytes. J Immunol 185:6985-98
Machida, Keigo; Liu, Jian-Chang; McNamara, George et al. (2009) Hepatitis C virus causes uncoupling of mitotic checkpoint and chromosomal polyploidy through the Rb pathway. J Virol 83:12590-600
Machida, Keigo; Tsukamoto, Hidekazu; Mkrtchyan, Hasmik et al. (2009) Toll-like receptor 4 mediates synergism between alcohol and HCV in hepatic oncogenesis involving stem cell marker Nanog. Proc Natl Acad Sci U S A 106:1548-53
Machida, Keigo; Kondo, Yasuteru; Huang, Jeffrey Y et al. (2008) Hepatitis C virus (HCV)-induced immunoglobulin hypermutation reduces the affinity and neutralizing activities of antibodies against HCV envelope protein. J Virol 82:6711-20
Lai, Chao-Kuen; Jeng, King-Song; Machida, Keigo et al. (2008) Hepatitis C virus NS3/4A protein interacts with ATM, impairs DNA repair and enhances sensitivity to ionizing radiation. Virology 370:295-309
Kawamura, Hiroki; Aswad, Fred; Minagawa, Masahiro et al. (2006) P2X7 receptors regulate NKT cells in autoimmune hepatitis. J Immunol 176:2152-60
Machida, Keigo; Cheng, Kevin T-H; Lai, Chao-Kuen et al. (2006) Hepatitis C virus triggers mitochondrial permeability transition with production of reactive oxygen species, leading to DNA damage and STAT3 activation. J Virol 80:7199-207
Dennert, Gunther; Aswad, Fred (2006) The role of NKT cells in animal models of autoimmune hepatitis. Crit Rev Immunol 26:453-73
Machida, Keigo; Cheng, Kevin T H; Sung, Vicky M-H et al. (2006) Hepatitis C virus induces toll-like receptor 4 expression, leading to enhanced production of beta interferon and interleukin-6. J Virol 80:866-74

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