IL28B genetic variation and treatment response in patients with hepatitis C virus genotype 3 infection

Polymorphisms near the IL28B gene, which code for interferon (IFN)-λ3, predict response to pegylated interferon-α (PEG-IFN) and ribavirin treatment in hepatitis C virus (HCV) genotype 1 infected patients. Follow-up studies of the effect of IL28B gene in HCV non-genotype 1 infected patients have almost always used predominantly HCV genotype 2-infected or mixed genotype 2/3-infected cohorts with results partly conflicting with HCV genotype 1. We performed a retrospective analysis of 281 patients infected with HCV genotype 3 for association of response to therapy with IL28B polymorphisms. We found that the HCV genotype 1 responder genotypes at rs12979860 and rs8099917 did not associate with sustained virological response to PEG-IFN/ribavirin therapy. However, the responder genotypes of both SNPs showed association with rapid viral response measured at 4 weeks (rs12979860, P = 3 × 10(-5) ; rs8099917, P = 3 × 10(-4) ). In multivariate analysis, age (<40 years), baseline viral load (<4 × 10(5) IU/mL) and the responder genotypes of SNPs rs12979860 or rs8099917 remained significant independent predictors of rapid viral response to therapy. Furthermore, we show that IL28B polymorphisms are associated with relapse in patients who achieve rapid viral response to PEG-IFN/ribavirin therapy. The responder genotypes also showed association with markers of stage and activity of liver disease, namely high aspartate aminotransferase platelet ratio index (APRI, rs12979860, P = 0.018; rs8099917, not significant) and high alanine aminotransferase (ALT, rs12979860, P = 0.002; rs8099917, P = 0.001), in addition to a high baseline viral load (rs12979860, P = 1.4 × 10(-5) ; rs8099917, P = 7.3 × 10(-6) ). CONCLUSION: Polymorphisms near the IL28B gene show association with rapid viral response but not sustained viral response to PEG-IFN/ribavirin therapy in HCV genotype 3-infected patients.