ABSTRACT
<p><b>OBJECTIVES</b>To investigate the quasispecies dynamics of hepatitis B virus (HBV) during the course of exacerbation and resolution of chronic hepatitis B in a patients.</p><p><b>METHODS</b>Five serum samples were collected from a patient with two episodes of exacerbation and resolution of chronic hepatitis B. A method of PCR-TA cloning-conformation sensitive gel electrophoresis (CSGE)-sequencing was performed to study the dynamic changes of HBV quasispecies in basal core promoter (BCP), precore and core regions of HBV genome.</p><p><b>RESULTS</b>Quasispecies complexity was 10 and 12 at the points of exacerbations, and 14 and 17 at the points of resolutions (t = 3.133, P < 0.05). Ratio of dominant quasispecies in HBV population was high (42.4% and 51.5%) during exacerbations and low (30.3% and 21.2%) during resolutions (t = 3.295, P < 0.05). All dominant quasispecies, except the one during the second resolution, carried core P5T, L60V, S155T, and precore G1896A mutations.</p><p><b>CONCLUSION</b>The composition of HBV quasispecies changes due to the change of host immune status, and immune pressure might lead to the selection of immune escape mutants.</p>