Sequence Variations of Hepatitis B Virus Promotor Regions in Vertically Transmitted Mother-child Pairs

수직 감염된 B형 간염 바이러스 Promoter 유전자의 변이 분석

  • Lee, Choong-Won (Department of Pediatrics, Korea University School of Medicine) ;
  • Han, Young-Na (Department of Pediatrics, Korea University School of Medicine) ;
  • Lee, Jung-Hwa (Department of Pediatrics, Korea University School of Medicine) ;
  • Lee, Kwang-Chul (Department of Pediatrics, Korea University School of Medicine) ;
  • Ha, Young-Mee (Department of Life Science, Yonsei University)
  • 이충원 (고려대학교 의과대학원 소아과학교실) ;
  • 한영나 (고려대학교 의과대학원 소아과학교실) ;
  • 이정화 (고려대학교 의과대학원 소아과학교실) ;
  • 이광철 (고려대학교 의과대학원 소아과학교실) ;
  • 하영미 (연세대학교 문리대 생명과학과)
  • Received : 2002.02.15
  • Accepted : 2002.03.07
  • Published : 2002.03.30

Abstract

Hepatitis B viral infection which affect about 10% of Korean population manifests asymptomatic carrier, chronic hepatitis and liver cirrhosis and even associates with hepatocellular carcinoma. Clinical manifestations induced by hepatitis B virus vary depending on the degree of immune response by cytotoxic T cells against viral epitope-presenting liver cells. Since hepatitis B virus presents high rate of mutaton that might change the presented epitope and eventually alter immune response, viral mutations, especially in promoters and enhancers, have an important implication in hepatic inflammation and viral replication. To identify mutations related to the hepatic inflammation, we investigated sequence variations of hepatitis B viral promotor regions in the presence or absence of symptoms in hepatitis B carriers. For this, sera from persistently hepatitis B virus-infected mother-child pairs were collected. After PCR amplifiation of all hepatitis B viral promoters (C promoter, S1 promoter, S2/S promoter, X promoter) using serum DNA from each pair, viral promotors were sequenced by automatic sequencer and then sequence data were analyzed by ClustalW. In most cases, the dominant type of maternal virus was transmitted to the child. However, in some children, some new host specific viral variants could be observed in Cp, S1p and S2/Sp. The mutations in C promoter did not seem to be vertically transmitted but arose in new host independently after the wild type had been transmitted. Enhancer I containing X promoter revealed high host specific variations as has been reported before. Two S promoters, S1p and S2/Sp, have shown some point mutations in children, but no deletion mutations were detected as in chronic hepatitis patients in whom deletion mutations are frequently found. In conclusion, the children with the vertically transmitted hepatitis B virus mostly retain the dominant type virus that had been transmitted. However, host specific variants tended to accumulate over time, possibly as clinical symptoms develop.