在在有 non-B 的一个病人的肝炎 B 病毒 DNA 的 X 区域的开始 codon 的一个变化， non-C 长期的肝炎

There are cases of hepatitis involving occult hepatitis B virus(HBV)infection in which,even though the HB surface antigen(HBsAg)is negative,HBV-DNA is detected by a polymerase chain reaction(PCR).We con-ducted a sequence analysis of the entire HBV region in a case of non-B non-C chronic hepatitis in a 46-yearold female.A diagnosis of non-B non-C chronic hepatitis was made.Although HBV markers,such as HBs antibody(anti-HBs),anti-HBc,HBeAg and anti-HBe,were negative,HBV-DNA was positive.Nested PCR was performed to amplify the precore region of HBV-DNA and all remaining regions by long nested PCR.Sequence analysis of the two obtained bands was conducted by direct sequencing.Compared with the control strains,the ATG(Methionine)start codon in the X region had mut ated to GTG(Valine).It is assumed that a mutation at the start codon in the X region may be the reason why HBV markers are negative in some cases of hepatitis that involve occult HBV infection.