To estimate the diagnostic and infectivity evaluation efficiency of polymerase chain reaction (PCR) in chronic hepatitis B, twelve HBs antigen positive and HB antigen negative sere from chronic hepatitis patients were tested by PCR. Serological
markere
were tested by ELISA. All the sera tested showed 270 bp DNA bands and were PCR positive, so PCR was proven to be a very efficient diagnostic and infectivity evaluation method in chronic hepatitis B.
In order to investigate the mutations in HBc region DNA from HBe antigen negative sera of chronic hepatitis patients, PCR product DNAs were cloned into a T-vector system(Pt7Blue) and the insert DNAs were identified by restriction enzyme digestion
and by
PCR. And nucleotide sequences of HBc region DNA were analyzed by dideoxy-chain terminating method. In one serum tested, three point mutations were found in DNA sequences 2,119(Adenine to Thymine), 2,120(Adenine to Guanine), and 2,121(Guanine to
Thymine)
resulted in two codon changes(GGA to GGT, to GTT) and one amino acid change(serine to valine). In another serum tested, one point mutation was found in DNA sequence 2,062(Adenine to Guanine) resulted in one codon change(GCA to GCG). The mutations
in
core region DNA might alter the core protein structure and its protease function, that could results in breaking the HBe antigen production.
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