Infection with hepatitis B virus genotype A in Tokyo, Japan during 1976 through 2001.
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.
Kobayashi
Mariko
M
Research Institute for Hepatology, Toranomon Hospital, 1-3-1 Kajigaya, Takatsu-ku, 213-8587 Kawasaki, Japan.
Suzuki
Fumitaka
F
Arase
Yasuji
Y
Akuta
Norio
N
Suzuki
Yoshiyuki
Y
Hosaka
Tetsuya
T
Saitoh
Satoshi
S
Kobayashi
Masahiro
M
Tsubota
Akihito
A
Someya
Takashi
T
Ikeda
Kenji
K
Matsuda
Marie
M
Sato
Junko
J
Kumada
Hiromitsu
H
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
D004279:DNA, Viral