Mutation analysis was performed in subgenotype B2 HBV RT/S sequences of CHB patients.
49.7% of RT and 33.6% of S sequences had substitutions at 74 studied AA sites.
The rtN134D/S (30.8%) and sT126A/S (15.4%) were most frequently detected.
RT/S substitutions were associated with lower serum HBV DNA and HBsAg levels.
HBsAg level was negatively associated with S protein sequence substitution rate.