Summary. Increased levels of chemokines (CK) in chronic hepatitis C virus (HCV) infection have been found. Given that NS5A and core can function as transcriptional transactivators, we aimed to determine whether these HCV proteins might induce CK gene expression in human hepatocyte-derived cells. We assessed (i) regulated upon activation, normal T cells expressed and activated (RANTES), interferon γ-inducible protein-10 (IP-10), and monokine induced by interferon-γ (MIG) mRNA levels in NS5A and core stably transfected Chang liver (CHL) cells, stimulated or not with a cytokine mixture (CM), by reverse transcriptase-polymerase chain reaction (RT-PCR) and (ii) quantitative enzyme-linked immunosorbent assay (ELISA) measurements of these CK in the supernatants of CHL cells. Induction of RANTES transcripts in resting HCV-transfected cells was clearly observed, being augmented fourfold in resting NS5A-transfected cells and threefold in resting core-transfected cells over that in resting mock-transfected (control) cells, as well as to a similar extent in CM-stimulated NS5A- and core-transfected cells. Increased RANTES secretion followed the same pattern observed for mRNA expression. Both IP-10 and MIG, such as mRNA and protein levels, were undetectable in resting HCV-transfected and -untransfected cells, whereas IP-10 and MIG mRNA expression was increased by seven- and fivefold in CM-stimulated NS5A-transfected cells and by 10- and 3.5-fold in CM-stimulated core-transfected cells, respectively, above that in CM-stimulated control cells. IP-10 and MIG secretion was enhanced by 2.6- and threefold in CM-stimulated NS5A-transfected cells and by 3.6-fold and 3.7-fold in CM-stimulated core-transfected cells, respectively over that in CM-stimulated control cells. These results demonstrate that NS5A and core proteins, alone or by the synergistic effect of cytokines, are capable of upregulating RANTES, IP-10 and MIG gene expression in cultured human hepatocyte-derived cells.