Pathogenicity of human Hepatitis C virus relying on enzymatic properties of viral RNA-dependent RNA-polymerase

Chronic hepatitis C (HepC) affects 70 million people world-wide manifesting in liver fibrosis, cirrhosis and hepatocellular carcinomas. HCV circulates in quasispecies. High variability/quasispecie diversity associates with elevated ALT levels and unfavorable disease progression. Molecular mechanisms behind are not fully understood. Disease progression depends on many factors, including viral replication fitness orchestrated by nonstructural proteins. Key role is played by RNA dependent RNA polymerase/RdRp which synthesizes HCV RNA. Our aim is to delineate the effects of variability in RdRp on enzymatic activity and clinical parameters of the disease in patients harboring respective viruses. Study includes 32 RdRp sequences from HepC patients with abnormal and persistently normal ALT levels (submitted to Genbank). We will: 1) clone RdRp cDNA for eukaryotic expression and assess expression levels; 2) determine specific activity of RdRps in eukaryotic cells; 3) determine activity of RdRps in vivo using capacity of polymerization products to induce expression of type I interferons; 4) identify signatures associated with high RdRp activity; 5) correlate RdRp activity to virus load, ALT levels and fibrosis scores in HepC patients bearing respective enzyme variants. This will identify ‘molecular signatures´ of clinical course of chronic hepatitis C related to replication capacity of infecting virus, guiding timely introduction of therapy with directly acting antiviral drugs.