By deep sequencing, viral mutants associated with BMN-673 DAA resistance and present as minor populations could be detected.[12-14] Because daclatasvir is considered to be a key DAA for therapy for HCV in the near future, we tried to clarify the possible clinical significance of HCV-resistance mutations, such as Y93H,

in the treatment response and their possible association with other viral and host factors. The subjects were 110 randomly selected, daclatasvir treatment-naïve patients who were infected with genotype 1b HCV and followed up at the Yamanashi University Hospital. The 110 patients included 59 naïve patients, 30 relapser patients (defined as patients with reappearance of HCV RNA after the completion of previous PEG IFN/RBV combination therapy carried out between 2005 and 2011) and 21 null responder patients (defined as patients without a 2 log drop of HCV RNA at week 12 compared to that at week 0 during previous PEG IFN/RBV combination therapy carried out between 2005 and 2011). These three groups of patients with distinctly different treatment responses to previous therapy (naïve, relapse and null) were included in this study to clarify whether the rate of NS5A mutations varies among different backgrounds of the treatment

response. None of the 51 patients who had failed to eradicate the virus during PEG IFN/RBV combination therapy had received antiviral therapy thereafter. VEGFR inhibitor In the 110 patients, daclatasvir-resistance mutations were analyzed by deep sequencing of sera collected and stored at the

most recent visit to the hospital. All patients studied fulfilled following criteria: (i) negative for hepatitis B surface antigen; (ii) no other forms of hepatitis, such as primary biliary 上海皓元 cirrhosis, autoimmune liver disease or alcoholic liver disease; (iii) free of co-infection with HIV; and (iv) signed consent was obtained for the study protocol that had been approved by Human Ethics Review Committee of Yamanashi University Hospital. The clinical backgrounds of the 110 patients are shown in Table 1. Hepatitis C virus RNA extraction, complementary DNA synthesis, amplification by two-step nested polymerase chain reaction (PCR) from serum samples using primers specific for partial viral regions and direct sequencing were carried out as described previously.[15, 16] Generated sequence files were assembled using Vector NTI software (Invitrogen, Tokyo, Japan) and base-calling errors were corrected following inspection of the chromatogram. This direct sequencing procedure was performed to determine the dominant viral sequences of the core,[17] the IFN sensitivity-determining region (ISDR)[18] and the IFN-ribavirin resistance determining region (IRRDR)[19] from the serum of each patient. Recent reports have disclosed a significant correlation between polymorphisms in the IL28B gene and patients’ responses to PEG IFN plus RBV therapy for HCV.