Associations between responses to interferon therapy and genetic variation in interleukin-28B and the core region of hepatitis C virus genotype 3a

The single-nucleotide polymorphism (SNP) of interleukin-28B (IL-28B) and mutations in the core region of hepatitis C virus (HCV) genotype 1b have been associated with response to interferon (IFN) therapy. However, whether this IL-28B SNP affects responses to INF therapy for HCV genotype 3a is not known. The aim of this study is to investigate whether this IL-28B SNP (rs8099917) and specific missense mutations in the HCV core region affect the response to IFN therapy for HCV genotype 3a. Patients (n=19; median age 44.5) infected with HCV genotype 3a who received IFN therapy were studied. Of the 19 patients, 12 (63.1%) achieved sustained virological response. Of those 12 patients, 11 had the TT genotype (11/16; 68.7%), and one had the TG genotype (1/3; 33.3%). The difference in the sustained virological response rate between IL-28B genotype groups was not significant (P=0.5232). HCV core region was well conserved; however, polymorphisms at position 72 were identified. Of the 19 HCV samples; 15 carried a glutamic acid at position 72, and these were defined as E type; the others (4/19) were defined as non-E type. Notably, there was a significant difference in the sustained virological response rate between E type and non-E-type; 12 of the 15 patients with E-type achieved sustained virological response, but none of the four patients with non-E-type achieved sustained virological response (P=0.009). A glutamic acid at position 72 in the core region of HCV genotype 3a was associated with a good response to IFN therapy.