Semmo Nasser, Principal Investigator,
Virus-specific T Cell Responses in Viral Hepatitis
Worldwide, about 170 million people are infected with Hepatitis C virus (HCV). There is considerable evidence that T cell responses play an important role in the outcome of HBV and HCV infection, e.g. viral elimination versus persistence.
Viral persistence is due to multiple mechanisms leading to the failure of the virus-specific T cell responses. These mechanisms include primary T cell failure, T cell exhaustion, viral escape mutants, as well as T cell dysfunction. Once viral persistence has been established, HBV or HCV infection can progress to liver fibrosis and cirrhosis with an enhanced risk for HCC.
The focus of our group is the identification and characterization of virus-specific CD4+ T cell responses during acute and chronic HBV and HCV infection. Several groups have demonstrated that during chronic HCV infection, HCV-specific CD4+ T cell responses are weak or absent. However, the functional status of HCV-specific CD4+ T cells in persistent infection is poorly understood and it may be necessary to use various techniques for their detection.
In the last years, using HCV proteins and overlapping peptides, we have been able to identify HCV-specific CD154+CD4+ T cells in chronic HCV infection that are enriched in the liver. These cells do not produce IFNγ and IL-2 and do not have the ability to proliferate (IFNγ/IL-2/proliferation), suggesting that HCV-specific CD4+ T cells do exist, but lack function.
T cell dysfunction
T cell exhaustion
Viral clearance prediction
CD154/CD40 ligand expression
Humans : Animals
24 : 1
CD4+ T lymphocytes
T lymphocyte epitopes