• acute hepatitis;
  • chronic hepatitis;
  • genotypes;
  • hepatitis B virus;
  • interferon;
  • lamivudine


Among the 97 adult patients with acute hepatitis B who were admitted to the Toranomon Hospital in Metropolitan Tokyo during 28 years from 1976 to 2003, 31 (32%) were infected with hepatitis B virus (HBV) genotype A, nine (9%) with genotype B, 44 (45%) with genotype C, one (1%) each with genotypes E and F. HBV in the remaining 11 (11%) patients were untypeable. All the 31 patients with acute hepatitis B caused by HBV genotype A infection were male with a median age of 31 years, and 16 (52%) contracted infection through extramarital sexual contacts. The baseline HBV DNA level was higher in the seven (23%) patients in whom infection with HBV genotype A persisted than the remaining 24 (77%) with spontaneous resolution (median: >8.7 vs. 6.0 log genome equivalents/ml, P = 0.004). Persistent infection was more frequent in patients with maximum alanine aminotransferase <500 IU/L than ≥500 IU/L (83% [5/6] vs. 4% [1/25], P = 0.0001). Of the six patients with persistent HBV genotype A infection who received interferon and/or lamivuidine for treatment of chronic active hepatitis, three (50%) responded with the loss of hepatitis B e antigen (HBeAg); hepatitis B surface antigen (HBsAg) was cleared from serum in one patient who received interferon and lamivudine in sequence. HBV genotype A persisted along with HBeAg in the remaining three patients given antiviral therapy as well as another who was not treated. In conclusion, infection with HBV genotype A prevails in patients with acute hepatitis B in Japan where genotypes B and C are common, is often contracted sexually (16/31 [52%]) and tends to persist (7/31 [23%]). Infection was cleared in only one of the six (17%) patients who received antiviral therapy. J. Med. Virol. 76:33–39, 2005. © 2005 Wiley-Liss, Inc.