Engineering the Jak-STAT pathway to overcome Hepatitis C Virus resistance to interferon
Description
Approximately 3% of the global population is chronically infected by the Hepatitis C Virus (HCV). The only approved treatment for chronic HCV infection, pegylated interferon-alpha (IFN-alpha) plus ribavirin clears the virus in less than half of genotype 1 infected patients. The precise molecular mechanisms of HCV resistance to IFN-alpha are unclear, therefore we sought to uncover HCV resistance mechanisms utilizing a stable human hepatoma cell line containing sub-genomic HCV that is resistant to interferon. Characterization of this resistant cell line revealed that a truncated IFNAR1gives rise to the IFN-alpha resistant phenotype. These in vitro findings were then confirmed in human explant liver samples obtained from patients with and without HCV infection. Next we employed a novel strategy utilizing constructs containing the TAD of STAT1 or STAT2 fused to IRF9 in an attempt to circumvent Jak-STAT cellular defects in the resistant cell line. The STAT2 TAD fusion product showed antiviral and immunoregulatory activity in the resistant cell line and caused minimal toxicity. A second novel strategy utilized a STAT1-CC double cysteine substituted construct that showed potent antiviral and immunoregulatory properties in the resistant cell line. In conclusion, IFNAR1 may play a role in IFN resistance in vivo and Jak-STAT pathway components can be engineered to overcome HCV resistance to IFN