Characterization of genotype H hepatitis B virus strain identified for the first time from a Japanese blood donor by nucleic acid amplification test.

The Japanese Red Cross has been conducting a nucleic acid amplification test (NAT) screening for hepatitis B virus (HBV), hepatitis C virus and human immunodeficiency virus 1 among blood donors since July 1 1999. The first case of HBV genotype H was found and reported in Japan. Serological markers of HBV were not detected in this NAT-positive donation. It may be that the positive donation was in the serological window period at the early stage of infection. The complete genome of 3215 nt was sequenced, and the sequence had 99.3 % homology with the strain from Los Angeles, USA (LSA2523). Here, a leucine zipper motif was found in the region of the HBV surface antigen conserved through genotypes A-H.