title: [X protein variations of genotype B and C hepatitis B virus isolated from the patients with hepatocellular carcinoma].
abstract: OBJECTIVE
  X protein was one of the most important pathogens of hepatitis B virus (HBV), and was crucial in the carcinogenesis of HBV related hepatocellular carcinoma (HCC). It was demonstrated that the infection of genotype B or C HBV would result in different clinical manifestations and pathological characteristics in HCC patients, however, it was under elucidation whether these differences related to different genotypes of HBV X protein. This study was designed to investigate the amino acid differentiations of X proteins in standard genotype B or C HBV strains and the variations in HBV isolated from the HCC patients, and elucidate preliminarily the relationship between the genotype of HBV and carcinogenesis of HCC.
  
  
  METHODS
  HBV X genes from the serum of twenty-two HBsAg positive HCC patients were amplified, cloned and sequenced. Genotyping of the X gene was carried out by Vector NTI6.0 software and the amino acid alignment among the standard and HCC originated X protein were done by DNAMAN software.
  
  
  RESULTS
  Twenty-two HBV X genes were obtained and all of them could be categorized into genotype B or C. Besides of 14 amino acid differentiations within X protein between standard B and C HBV strains, HCC originated X protein of B and C genotype showed 4 consensus amino acid variations, and genotype C X protein showed additional 6 genotype-specific variations. All these differentiated and varied amino acids were located in the B, T cell epitopes and transactive or related regulatory regions.
  
  
  CONCLUSIONS
  In addition to amino acid differentiations, X protein of genotype B or C HBV also showed genotype-specific variations in HCC patients. Amino acid differentiations and variations may result in the different immunocompetence and transactivation capacity between X proteins of genotype B and C.
authors.affiliation: Research Center of Molecular Medicine, Fujian Medical University, Fuzhou, Fujian, 350004, P.R.China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Xu
authors.forename: Wan-Nan
authors.initials: WN
authors.lastname: Chen
authors.forename: Da-Li
authors.initials: DL
authors.lastname: Zheng
authors.forename: Qing-Ling
authors.initials: QL
authors.lastname: Huang
authors.forename: Xu
authors.initials: X
authors.lastname: Lin
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000821:virology; D003001:Cloning, Molecular; D004279:DNA, Viral / Q000235:genetics / Q000302:isolation & purification; D005838:Genotype; D006511:Hepatitis B Antigens / Q000235:genetics; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D008113:Liver Neoplasms / Q000235:genetics* / Q000821:virology; D008969:Molecular Sequence Data; D017354:Point Mutation; D015534:Trans-Activators / Q000235:genetics*; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004279:DNA, Viral; D006511:Hepatitis B Antigens; D015534:Trans-Activators; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein