To identify the regions in the genotype 1b HCV genome that govern the efficiency of HCVcc replication, we isolated HCV genomes with distinctive phenotypes from two patients with different clinical symptoms, including the efficacy of IFN therapy (Table 1): patient TPF1 had recurrent fulminant hepatitis after liver transplantation, and patient sAH had acute hepatitis. The gene discussed is IFNA1; the disease is Acute hepatitis.