MUTATIONS IN THE CORE PROMOTER ENHANCER-II REGIONS OF NATURALLY-OCCURRING HEPATITIS-B VIRUS VARIANTS AND ANALYSIS OF THE EFFECTS ON TRANSCRIPTION ACTIVITIES

The regulatory regions for transcription and replication of several he patitis B virus (HBV) genomes from 19 patients having various forms of HBV infection were sequenced. Predominant mutations were found to occ ur naturally in nucleotide positions 1752 (A to T) and 1764 (G to A) i n chronic hepatitis patients and in asymptomatic carriers after seroco nversion, but were not observed in HBeAg-positive healthy carriers. Si nce these positions were located in the basic core promoter and the ov erlapping enhancer II regions situated within the core upstream region , transcriptional activity was examined by chloramphenicol acetyltrans ferase assay to determine if there was a possible difference between t he mutant and wild-type HBV. However, no significant difference was de tected upon comparison of the promoter and enhancer activities between mutant and wild-type HBV.