Objective　　　 To investigate the relationship between amino acid substitutions in hepatitis C virus core region with the virological response (VR) to pegylated interferon.　　　 Methods　　　 The substitution pattern of amino acid in core region and whether it is associated with VR to pegylated interferon were analyzed retrospectively in a subset of HCV RNA-positive

chronically infected patients who were inpatients or outpatients of our department from December 2008 to October 2012. A to

tal of 108 patients were enrolled and divided into 2 groups based on their final VR to pegylated interferon

sustained VR (SVR) group (n=76)

and non-SVR group (n=32). Serum viral RNA was extracted and full-length core gene was amplified through nested reverse-transcription polymerase chain reaction (RT-PCR).　　　 Results　　　 Hypermutated sites (with mutation frequency exceeding 10%) occurred at positions 70

75

91

106

110

147 and 187 amino acids of the core protein. The proportion of Glutamine (Q) and non-Q at position 70

methionine (M) and non-M at position 91

threonine (T) and non-T at position 110 of the core protein were significantly different between SVR and non-SVR group (

P

=0.004

0.039 and 0.025

respectively). Q at position 70

M at position 91 and T at position 110 were correlated with non-SVR with OR=0.288

0.413

0.346 and 95%CI=0.120-0.693

0.177-0.966

0.133-0.896

respectively. Patients carried 2 or more undesirable substitutions mentioned above simultaneously tended to attain slower viral decrease after 4 weeks’ treatment (P=0.001).　　　 Conclusion　　　 Amino acid substitutions at positions 70

91 and 110 of HCV core protein should be used as predictors of VR to pegylated interferon.