Source Department of Internal Medicine and Infectious Diseases, University Medical Center Utrecht (UMCU), Heidelberglaan 100, P.O. Box 85500, 3508 GA Utrecht, The Netherlands; Department of Immunology, University Medical Center Utrecht (UMCU), Heidelberglaan 100, P.O. Box 85500, 3508 GA Utrecht, The Netherlands.

Host polymorphisms in the IL28B region have recently been associated with outcome of treatment for hepatitis C virus (HCV) infection. This study clearly shows an association between first-phase viral load decrease and the IL28B rs12979860 polymorphism in chronic HCV-infected patients. Furthermore, a higher treatment efficiency factor (ɛ) was found in those HCV-infected patients with a CC genotype compared with those with a CT and TT genotype. This study highlights the importance of host response mechanisms in relation to favourable clearance of HCV.