BACKGROUND/AIMS: The amino acid sequence of NS5A2209-2248, named the "interferon sensitivity-determining region" (ISDR), has been reported to correlate with responsiveness of interferon (IFN) therapy to patients with the hepatitis C virus (HCV) genotype-1b, by several Japanese authors. However, European authors have failed to find this phenomenon, suggesting a difference in HCV-1b isolates between Japan and Europe. METHODS: We compared the HCV-1b nucleotide sequences of our Japanese patients and those of other countries quoted from GenBank, using the envelope 1 sequence. RESULTS: A phylogenetic tree analysis revealed two characteristic groups from a geographical viewpoint: one group (NJ group) consists of almost entirely non-Japanese isolates, and the other (J group) of almost entirely Japanese isolates. The isolates other than the NJ and J groups are characterized by their specific nucleotide residue, constructing an individual group (W group). Japanese HCV-1b isolates consist of the J group and W group (approximately 40% and 60%, respectively). Comparative study between the two groups in Japanese patients treated with IFN revealed a strong correlation between ISDR type and IFN responsiveness only in the J group, but not in the W group. CONCLUSIONS: These observations convinced us that the existence of the Japan-specific J group is one reason why the ISDR system is useful only in Japan.
BACKGROUND/AIMS: The amino acid sequence of NS5A2209-2248, named the "interferon sensitivity-determining region" (ISDR), has been reported to correlate with responsiveness of interferon (IFN) therapy to patients with the hepatitis C virus (HCV) genotype-1b, by several Japanese authors. However, European authors have failed to find this phenomenon, suggesting a difference in HCV-1b isolates between Japan and Europe. METHODS: We compared the HCV-1b nucleotide sequences of our Japanese patients and those of other countries quoted from GenBank, using the envelope 1 sequence. RESULTS: A phylogenetic tree analysis revealed two characteristic groups from a geographical viewpoint: one group (NJ group) consists of almost entirely non-Japanese isolates, and the other (J group) of almost entirely Japanese isolates. The isolates other than the NJ and J groups are characterized by their specific nucleotide residue, constructing an individual group (W group). Japanese HCV-1b isolates consist of the J group and W group (approximately 40% and 60%, respectively). Comparative study between the two groups in Japanese patients treated with IFN revealed a strong correlation between ISDR type and IFN responsiveness only in the J group, but not in the W group. CONCLUSIONS: These observations convinced us that the existence of the Japan-specific J group is one reason why the ISDR system is useful only in Japan.
Authors: Joonho Yoon; Jong In Lee; Soon Koo Baik; Kwang Ho Lee; Joon Hyung Sohn; Hyean Woo Lee; Jun Namkung; Sei Jin Chang; Jong Whan Choi; Hyun Won Kim; Byung-Il Yeh Journal: World J Gastroenterol Date: 2007-12-14 Impact factor: 5.742
Authors: K Nagayama; N Enomoto; N Izumi; M Kurosaki; Y Miyasaka; H Watanabe; J Itakura; C H Chen; J Tazawa; Y Hoshino; T Ikeda; F Marumo; C Sato Journal: Gut Date: 2001-06 Impact factor: 23.059
Authors: Cíntia Bittar; Ana Carolina G Jardim; Lilian H T Yamasaki; Artur T L de Queiróz; Claudia M A Carareto; João Renato R Pinho; Isabel Maria V G de Carvalho-Mello; Paula Rahal Journal: BMC Infect Dis Date: 2010-02-23 Impact factor: 3.090