Characterization of nucleotide sequence of hepatitis B surface gene and enhancer element of HBV

The HBV DNA sequence containing a primary part of pre-S2, the coding sequence of the major S protein and the enhancer sequence in pTWS1 was completely sequenced. A comparison with other previously published HBV sequences indicates that the nucleotide sequence homology in the pre-S2 region is 97%, 98% and 98% for adw, adr and ayw subtypes, respectively, and 76% among different subtypes. The nucleotide sequence homology in the major S protein region is 99% for each adw, adr and ayw subtype, and 90% among different subtypes. The important regulatory enhancer sequence (nucleotides 1036-1204) is identical in all subtypes.