title: Infection with hepatitis B virus genotype A in Tokyo, Japan during 1976 through 2001.
abstract: BACKGROUND
  Because genotype A of hepatitis B virus (HBV) is not indigenous, there have been only few data on infection with it in Japan.
  
  
  METHODS
  We examined clinical and virological features of the 66 Japanese patients who admitted Toranomon Hospital in Tokyo, Japan, between 1976 and 2001, who were found to have HBV/A infection. HBV genotype A was classified into subtype A (European type) and A' (South African type) by phylogenetic analysis of the preS1 and preS2 regions, and the S gene sequences.
  
  
  RESULTS
  Of the 66 patients infected with HBV/A, 14 (21%) were asymptomatic carriers, 26 (39%) presented with acute hepatitis, 22 (33%) with chronic hepatitis, and 4 (6%) with liver cirrhosis. HBV/A infection persisted for more than 6 months in 5 of the 26 (19%) patients with acute hepatitis. The frequency of acute hepatitis in patients infected with HBV/A was higher after than before 1991 (2/22 [9%] vs 24/44 [55%]; P < 0.0001). The frequency of nucleotide 1858 of T was higher in asymptomatic carriers than in patients with acute hepatitis in whom infection was resolved (5/14 [36%] vs 0/21 [0%]; P = 0.008). Of the 57 patients for whom subtypes of genotype A were determined, subtype A was identified in 53 (93%) and subtype A' in only 4 (7%). All patients infected with subtype A' were persistently infected with HBV.
  
  
  CONCLUSIONS
  HBV/A infection has become more frequent during recent years, predominantly presenting as acute hepatitis, and subtype A' is uncommon in the Tokyo metropolitan area.
authors.affiliation: Research Institute for Hepatology, Toranomon Hospital, 1-3-1 Kajigaya, Takatsu-ku, 213-8587 Kawasaki, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Suzuki
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Arase
authors.forename: Norio
authors.initials: N
authors.lastname: Akuta
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hosaka
authors.forename: Satoshi
authors.initials: S
authors.lastname: Saitoh
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Akihito
authors.initials: A
authors.lastname: Tsubota
authors.forename: Takashi
authors.initials: T
authors.lastname: Someya
authors.forename: Kenji
authors.initials: K
authors.lastname: Ikeda
authors.forename: Marie
authors.initials: M
authors.lastname: Matsuda
authors.forename: Junko
authors.initials: J
authors.lastname: Sato
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Kumada
mesh_terms: D000293:Adolescent; D000328:Adult; D004279:DNA, Viral / Q000235:genetics; D005260:Female; D005838:Genotype; D006509:Hepatitis B / Q000821:virology*; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011401:Promoter Regions, Genetic / Q000235:genetics; D016036:Seroepidemiologic Studies
chemical_list: D004279:DNA, Viral