The enhancer 2/core promoter and the X protein regions located upstream of the precore and core regions in hepatitis B virus regulate expression of core/e antigen peptides. Mutations in the precore and core regions have been reported to be associated closely with the severity of type B hepatitis, and regions regulating expression of these peptides may also be involved in severe liver damage. Mutations were examined in regions that may be related to fatal liver diseases. Nucleotide sequences and deduced amino acid sequences from 20 patients with fatal type B hepatitis (12 with fulminant hepatitis and 8 with severe exacerbation) and 10 patients with self-limited acute hepatitis were analyzed. There were 50 nucleotide alterations in the enhancer 2/core promoter region of virus from 12 patients with fulminant hepatitis (average 4.1/case), 37 alterations in 8 patients with severe exacerbation (4.6/case), and 10 mutations in 10 cases of acute hepatitis (1.0/case). The numbers of amino acid mutations in X protein were 53 in 12 cases of fulminant hepatitis (4.4/case), 27 in 8 cases of severe exacerbation (3.3/case), and 9 in 10 cases of acute hepatitis (0.9/case). In fatal cases, approximately 50% of the nucleotide mutations were located within the region spanning nucleotides 1741-1777 (14.2% of the enhancer 2/core promoter region) and 30% of the amino acid mutations in X protein were located within the region containing codons 122-132 (7.1% of X protein). In addition to mutations in the precore and core regions, mutations in the enhancer 2/core promoter and the X protein regions may be associated with the pathogenesis of fatal B hepatitis infection.
Copyright 2000 Wiley-Liss, Inc.