Diversity of core promoter mutations in immune clearance phase of chronic HBV infection

Transcription of HBV (hepatitis B virus) pre-core and pre-genomic mRNAs is controlled by core promoter. Therefore, mutations in the core promoter region might change the activity of liver diseases through an altered transcriptional level of the mRNA. The present study was carried out to determine the diversity of HBV core promoter sequences in chronic HBV carriers.

DNA sequences in the core promoter region were determined after cloning the PCR product. Two groups of chronic HBV carriers with HBeAg, including five cases of asymptomatic carriers (ASCs, 21 clones) and eight with chronic hepatitis (CH, 50 clones) were studied.

Mutations in the core promoter were found in three out of the ASCs (11 clones), and in all eight cases in the CH group (48 clones). While mutations at nucleotide 1762 (A-->T) and 1764(G-->A) were not found in ASC, mutations at the same positions were found in all the cases of CH group (40 clones) (P=0.003). Diverse patterns of mutations in the core promoter were observed in each patient in the CH group.

Further studies are needed to determine whether the diversity of HBV core promoter mutations has clinical significance such as the seroconversion of HBeAg to anti-HBe.