title: Occult infection related hepatitis B surface antigen variants showing lowered secretion capacity.
abstract: OBJECTIVE
  To elucidate the molecular mechanisms underlying hepatitis B virus (HBV) occult infection of genotype C.
  
  
  METHODS
  A total of 10 types of hepatitis B surface antigen (HBsAg) variants from a Korean occult cohort were used. After a complete HBV genome plasmid mutated such that it does not express HBsAg and plasmid encoding, each HBsAg variant was transiently co-transfected into HuH-7 cells. The secretion capacity and intracellular expression of the HBV virions and HBsAgs in their respective variants were analyzed using real-time quantitative polymerase chain reaction assays and commercial HBsAg enzyme-linked immunosorbent assays, respectively.
  
  
  RESULTS
  All variants exhibited lower levels of HBsAg secretion into the medium compared with the wild type. In particular, in eight of the ten variants, very low levels of HBsAg secretion that were similar to the negative control were detected. In contrast, most variants (9/10) exhibited normal virion secretion capacities comparable with, or even higher than, the wild type. This provided new insight into the intrinsic nature of occult HBV infection, which leads to HBsAg sero-negativeness but has horizontal infectivity. Furthermore, most variants generated higher reactive oxidative species production than the wild type. This finding provides potential links between occult HBV infection and liver disease progression.
  
  
  CONCLUSIONS
  The presently obtained data indicate that deficiency in the secretion capacity of HBsAg variants may have a pivotal function in the occult infections of HBV genotype C.
authors: Hong Kim, Seoung-Ae Lee, You-Sub Won, HyunJoo Lee, Bum-Joon Kim, Department of Biomedical Sciences, Microbiology and Immunology, and Liver Research Institute, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors: Hong
authors: H
authors: Kim
authors: Hong Kim, Seoung-Ae Lee, You-Sub Won, HyunJoo Lee, Bum-Joon Kim, Department of Biomedical Sciences, Microbiology and Immunology, and Liver Research Institute, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors: Seoung-Ae
authors: SA
authors: Lee
authors: Hong Kim, Seoung-Ae Lee, You-Sub Won, HyunJoo Lee, Bum-Joon Kim, Department of Biomedical Sciences, Microbiology and Immunology, and Liver Research Institute, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors: You-Sub
authors: YS
authors: Won
authors: Hong Kim, Seoung-Ae Lee, You-Sub Won, HyunJoo Lee, Bum-Joon Kim, Department of Biomedical Sciences, Microbiology and Immunology, and Liver Research Institute, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors: HyunJoo
authors: H
authors: Lee
authors: Hong Kim, Seoung-Ae Lee, You-Sub Won, HyunJoo Lee, Bum-Joon Kim, Department of Biomedical Sciences, Microbiology and Immunology, and Liver Research Institute, Seoul National University College of Medicine, Seoul 110-799, South Korea.
authors: Bum-Joon
authors: BJ
authors: Kim
mesh_terms: D000328:Adult; D000368:Aged; D045744:Cell Line, Tumor; D002675:Child, Preschool; D015536:Down-Regulation; D005260:Female; D015967:Gene Expression Regulation, Viral; D005838:Genotype; D006509:Hepatitis B / Q000175:diagnosis / Q000453:epidemiology / Q000821:virology*; D006514:Hepatitis B Surface Antigens / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D006515:Hepatitis B virus / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000472:pathogenicity; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010641:Phenotype; D017382:Reactive Oxygen Species / Q000378:metabolism; D056910:Republic of Korea / Q000453:epidemiology; D012189:Retrospective Studies; D014162:Transfection; D014774:Virulence
chemical_list: D006514:Hepatitis B Surface Antigens; D017382:Reactive Oxygen Species
keywords: Genotype C; Hepatitis B surface antigen; Hepatitis B virus; Occult infection; Reactive oxidative species; Variants