Comparison of Quasispecies Diversity of HCV between Chronic Hepatitis C and Hepatocellular Carcinoma by Ultradeep Pyrosequencing

Backgrounds. Hepatitis C virus (HCV) exists as population of closely related genetic variants known as quasispecies. HCV quasispecies diversity is strongly influenced by host immune pressure on virus. Quasispecies diversity is expected to decline as host immune response to HCV decreases over natural course of progressing from chronic hepatitis C (CHC) to hepatocellular carcinoma (HCC). Methods. Ultradeep pyrosequencing (UDPS) was used to evaluate degree of quasispecies diversity in 49 patients infected with HCV including 26 with CHC and 23 with HCC. Whole structural protein of HCV genome was subjected to UDPS. Results. Shannon's indices for quasispecies diversity in HCV E1 were significantly lower in patients with HCC than in those with CHC. 14 amino acid positions differed significantly between two groups. Area under curve of ROC analysis for differentiating HCC from CHC was >0.8 for all of 14 amino acid positions. Conclusion. HCV quasispecies diversity as indicator of declining host immune functions was easily assessed by UDPS technology. Shannon's indices in 14 amino acid positions were found to differentiate between patients with CHC and those with HCC. Our data propose that degree of HCV quasispecies measured by UDPS might be useful to predict progression of HCC in chronic HCV patients.