title: Evaluation of Interferon Resistance in Newly Established Genotype 1b Hepatitis C Virus Cell Culture System.
abstract: OBJECTIVE
  The hepatitis C virus (HCV) genotype 1b is known to exhibit treatment resistance with respect to interferon (IFN) therapy. Substitution of amino acids 70 and 91 in the core region of the 1b genotype is a significant predictor of liver carcinogenesis and poor response to pegylated-IFN-α and ribavirin therapy. However, the molecular mechanism has not yet been clearly elucidated because of limitations of the HCV genotype 1b infectious model. Recently, the TPF1-M170T HCV genotype 1b cell culture system was established, in which the clone successfully replicates and infects Huh-7-derived Huh7-ALS32.50 cells. Therefore, the purpose of this study was to compare IFN resistance in various HCV clones using this system.
  
  
  METHODS
  HCV core amino acid substitutions R70Q and L91M were introduced to the TPF1-M170T clone and then transfected into Huh7-ALS32.50 cells. To evaluate the production of each virus, intracellular HCV core antigens were measured. RESULTS were confirmed with Western blot analysis using anti-NS5A antibodies, and IFN sensitivity was subsequently measured.
  
  
  RESULTS
  Each clone was transfected successfully compared with JFH-1, with a significant difference in intracellular HCV core antigen (p < 0.05), an indicator of continuous HCV replication. Among all clones, L91M showed the highest increase in the HCV core antigen and HCV protein. There was no significant resistance against IFN treatment in core substitutions; however, IFN sensitivity was significantly different between the wildtype core and JFH-1 (p < 0.05).
  
  
  CONCLUSIONS
  A novel genotype 1b HCV cell culture was constructed with core amino acid substitutions, which demonstrated IFN resistance of genotype 1b. This system will be useful for future analyses into the mechanisms of HCV genotype 1b treatment.
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Taniguchi
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan; Center for Interprofessional Education, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Megumi
authors.initials: M
authors.lastname: Tasaka-Fujita
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan; Center for Interprofessional Education, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Mina
authors.initials: M
authors.lastname: Nakagawa
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan; Department of Medical Education Research and Development, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Takako
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Fukiko
authors.initials: F
authors.lastname: Kawai-Kitahata
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Otani
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Goto
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Nagata
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Shun
authors.initials: S
authors.lastname: Kaneko
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Sayuri
authors.initials: S
authors.lastname: Nitta
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Miyako
authors.initials: M
authors.lastname: Murakawa
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nishimura-Sakurai
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Seishin
authors.initials: S
authors.lastname: Azuma
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan; Department of Medical Education Research and Development, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Itsui
authors.affiliation: Advanced Life Science Institute, Saitama, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Mori
authors.affiliation: Advanced Life Science Institute, Saitama, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Yagi
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan; Department of Liver Disease Control, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Sei
authors.initials: S
authors.lastname: Kakinuma
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan; Department of Liver Disease Control, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Asahina
authors.affiliation: Department of Gastroenterology and Hepatology, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Watanabe
keywords: Cell culture system; Core Amino acid substitutions 70 and 91; Genotype 1b; Hepatitis C virus