Polymorphism of the IL28B gene (rs8099917, rs12979860) and virological response of Pakistani hepatitis C virus genotype 3 patients to pegylated interferon therapy.

BACKGROUND: The gold standard treatment for chronic hepatitis C virus (HCV) infection is pegylated interferon (PEG-IFN) in combination with ribavirin. Most patients treated with PEG-IFN achieve a sustained virological response (SVR). However host genetic factors play a vital role in the spontaneous and treatment-induced clearance of HCV infection from these infected patients. In the current study, polymorphisms of IL28B (rs8099917 and rs12979860) were analyzed and their association with the virological response to PEG-IFN alpha treatment was determined.

METHODS: One hundred and fifty HCV genotype 3 patients were assessed to study the correlation of IL28B with a therapeutic regimen of PEG-IFN alpha plus ribavirin. Twenty patients were excluded due to a refusal to participate in the study and 25 patients failed to meet the inclusion criteria. Of the 105 patients recruited, 49 (46.7%) were male and 56 (53.3%) were female. In order to determine single nucleotide polymorphisms of rs8099917 and rs12979860, the sample was amplified by PCR and then IL28B typing was carried out by restriction fragment length polymorphism (RFLP) followed by standard sequencing.

RESULTS: We found three types of genotype in rs8099917 of IL28B: wild-type TT in 60.0% of patients, heterozygous GT minor genotype in 36.2%, and GG in 3.8%. The frequency of the CC genotype of rs12979860 was 54.3%, CT was 37.1%, and TT was 8.6%. Overall, SVR was achieved in 68.6% of patients. A higher SVR was achieved for patients with the favorable genotype CC of rs12979860, with 84.2% as compared to 56.4% and 22.2% for minor genotype CT and TT, respectively (p=0.0001). We did not find a significant association for SVR to antiviral treatment in patients with genotype TT (rs8099917) (71.9%, p=0.36). The rapid virological response (RVR) rate was significantly higher in patients with major genotype TT (88.9%, p=0.04). These results show that IL28B polymorphism is highly associated with SVR to therapy in the Pakistani population infected with HCV genotype 3.

CONCLUSIONS: HCV-infected patients carrying homozygous C/C have a higher chance of SVR. In addition, patients who carry T/T (rs8099917) have a higher chance of RVR.