Up-regulation of hepatitis C virus replication by human T cell leukemia virus type I-encoded Tax protein

Jing Zhang, Osamu Yamada, Kenji Kawagishi, Hiroshi Yoshida, Hiromasa Araki, Shoji Yamaoka, Toshio Hattori, Kunitada Shimotohno

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Co-infection of hepatitis C virus (HCV) with other blood-borne pathogens such as human T cell leukemia virus (HTLV) is common in highly endemic areas. Clinical evidence showing a correlation between HTLV-I co-infection and rapid progression of HCV-associated liver disease promoted us to investigate the effect of HTLV-I-encoded Tax protein on HCV replication. Reporter assay showed that HCV replicon-encoded luciferase expression was significantly augmented by co-transfection of the Tax-expressing plasmid. Further, HCV RNA replication in replicon cells was increased either by co-culture with cells stably expressing Tax protein (Huhtax) or by culture in the presence of Huhtax-conditioned medium, indicating that Tax could also modulate HCV replication of adjacent cells in a paracrine manner. Additionally, HCV replication in Huhtax exhibited a reduced responsiveness to interferon-α-induced antiviral activity. This study demonstrates the facilitation of HCV replication by Tax protein, which may partially account for severer clinical consequences of HCV-related disease in HCV/HTLV co-infected individuals.

Original languageEnglish
Pages (from-to)198-205
Number of pages8
Issue number1
Publication statusPublished - 2007 Dec 5


  • Co-infection
  • HCV
  • HTLV-I
  • Replication

ASJC Scopus subject areas

  • Virology


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