Albumin-interferon alfa (alb-IFN) is a novel recombinant protein derived from IFNalpha-2b genetically fused to human albumin, which combines in a single polypeptide the antiviral properties of IFNalpha with the long serum half-life of albumin. Interferon alfa (IFNalpha) mediated biological responses stem from the engagement of IFNalpha with its target receptor and subsequent modulation of interferon-specific gene (ISG) expression. The dynamics of ISG expression were evaluated in a Phase 2a study conducted in IFNalpha naïve patients with genotype 1 chronic hepatitis C (CHC) treated with alb-IFN. Whole blood was obtained pre-dose and on days 7 and 28 from 47 patients enrolled to receive two subcutaneous injections of alb-IFN 14 days apart in five dose cohorts ranging from 200 to1200mug. Gene expression of nine candidate genes including four ISGs was determined by a TaqMan Real-time PCR assay. There was sustained >5-fold median induction on days 7 and 28 of the ISG's- OAS1, IRF7, IFI44 and IFI27. While all subjects showed a molecular response to alb-IFN, individual variability in pre-treatment gene expression levels and fold of modulation during treatment was observed. At days 7 and 28, induction of OAS1, IFI44 and IRF7 showed significant pair-wise correlation in individual patients (r>0.7 and P<0.001). There was no correlation of baseline expression or induction of gene expression with antiviral response. In conclusion, alb-IFN demonstrated robust induction of ISG that was consistent with the molecular response associated with an IFNalpha.