Analysis of hepatitis B virus quasispecies distribution in a Korean chronic patient based on the full genome sequences.

Although Korea is a hepatitis B virus (HBV) endemic area, relatively few full-length genome sequences are available. In particular, no comparative analysis has been performed on the full-genome sequences of different HBV quasispecies from a single Korean patient. This report describes the full-length sequences of five HBV clones (two clones with shorter PCR amplicons and three clones with longer amplicons). Large deletions, that is, 685-bp, 487-bp, and 144-bp, that might interfere with the production of normal proteins were observed in four of five clones. Double mutations in the basal core promoter (BCP) region (T1762/A1764) were detected in two clones but no precore mutations (A1896) were detected in any of the five clones. These data support previous results that genotype C, in particular Korean clones of this genotype, is prone to mutations. Two independent mechanisms, namely, the deletions of long lengths and amino acid substitutions followed by BCP double mutations might contribute to the diversity of HBV quasispecies. Considering the importance of HBV quasispecies as HBV variant sources, the distribution of HBV quasispecies in mutation prone genotype C prevalent areas like Korea, should be monitored to improve the management of chronic HBV infections and to control HBV variants that arise due to the administration of vaccine or antiviral therapy.