Furthermore, using 53 partial genome sequences, correlation among HBeAg/anti-HBe status, viral load and key mutations were analyzed. The data showed that PC mutation is associated with HBeAg seroconversion and enhanced viral replication efficiency. Comparison between HBV/E and HBV/D strains reveals these two genotypes to have an identical sequence in their core-promoter-upstream and basic core promoter (CURS/BCP) regions. It has been known from the previous phylogenetic studies, that HBV/D and HBV/E cluster together in trees reconstructed on X and preCore/Core ORFs. In addition, this study, demonstrates that in spite of the high sequence similarity of CURS/BCP region, the seroconversion-related mutation patterns are different between HBV/E and HBV/D in ASC. Further studies are needed to clarify the clinical significance of the regulatory sequence similarity between HBV/E and HBV/D.