| Theme |
Cutting Edge : Pathogenesis and Treatment of Hepatitis B |
| Title |
HBV Genotypes : Global Overview |
| Author |
Masaya Sugiyama |
Department of Clinical Molecular Informative Medicine, Graduate School of Medical Sciences, Nagoya City University |
| Author |
Yasuhito Tanaka |
Department of Clinical Molecular Informative Medicine, Graduate School of Medical Sciences, Nagoya City University |
| Author |
Masashi Mizokami |
Research Center for Hepatitis & Immunology, Kohnodai Hospital International Medical Center of Japan |
| [ Summary ] |
Hepatitis B virus (HBV) is classified into eight genotypes (A to H) by a sequence divergence of > 8% over the entire genome. HBV genotypes have different geographic distributions and unique virological characteristics. Because at most two genotypes prevail in any given country, comparisons have been restricted to HBV/B and HBV/C in Asia and HBV/A and HBV/D in Europe/USA. However, direct comparisons using in vitro and in vivo systems have revealed the unique virological differences of each HBV genotype. As described in previous reports, HBV genotypes exhibit distinct clinical characteristics. HBV/A can persist in up to 10% of infected adults. Patients infected with HBV/D have an increased resistance to interferon treatment compared to those with HBV/A. HBV/B is divided into two groups, the first is HBV/B1 (Bj) which is a non-recombinant type, which is wide spread only in Japan. The other group, HBV/B2-B5 (Ba) harboring a partial recombination with HBV/C has been detected in Asian countries outside Japan. HBV/B2-B5 and HBV/C infections lead to more severe liver disease than HBV/B1. The above characteristics could be based on HBV genotypes and the irfeatures. The diagnosis of HBV genotypes could be a useful tool to predict liver disease progression as well as interferon sensitivity. |