Shifting hepatitis B virus genotypes of acute hepatitis B patients in northeast Japan

It has been reported that acute hepatitis B (AHB) patients with genotype A HBV (HBV/A) have been increasing since the 1990s in metropolitan areas in Japan. However, little is known about the trends of HBV genotypes in AHB patients in northeast Japan where genotype B HBV (HBV/B) prevails more than in other areas. In this study, we aimed to clarify the changes in the HBV genotypes and clinical characteristics of AHB patients in this area. HBV genotypes were determined by direct sequencing (n=125) or enzyme immunoassay (n=9) using serum samples from AHB patients including fulminant hepatitis in 1987-2014. Among 134 patients, 26 (19%), 33 (25%), and 75 (56%) patients were infected with HBV of genotypes A, B, and C, respectively. HBV/A emerged from 2001 and the percentage was increased gradually up to 48% in 2010-2014, whereas HBV/B was reduced from 40% in 1987-1994 to 10% in 2010-2014. Phylogenetic analysis showed that three major subgenotype A2 strains had come into this area serially. The levels of HBV DNA and prothrombin time were higher in HBV/A patients than other genotypes. This study could not show significant difference in the HBsAg-positive period among genotypes nor the effect of nucleoside analogues to shorten the HBsAg-positive period. A higher level of initial HBV DNA was associated with late disappearance of HBsAg. In conclusion, the percentage of HBV/A in AHB patients has been increasing in northeast Japan since 2001, which is later than metropolitan areas, whereas that of HBV/B is decreasing. J. Med. Virol. 88:69-78, 2016. (c) 2015 Wiley Periodicals, Inc.