Abstract

In addition to high viral copy number during replication, HBV reverse transciptase also does not have a proofreading function, therefore, many HBV genotypes, subgenotypes, mutants and recombinants can emerge. To date, 10 HBV genotypes (A-J) and almost 40 subgenotypes have been identified. Genotype A is dominant in Northwest Europe, North America and Africa; genotype B and C are common in Asian countries; genotype C is more dominant in East and Southeast Asian countries. Genotype D is widespread in the whole world and is endemic in the Meditteranean area, the Middle East and Western Asia. Genotype E is dominant in Western Africa and genotype H has been found in Central and South America. Genotype G has been reported in France, Germany and America. The genotype H is found in Central America. Recently identified genotype I, a recombination of genotypes A, C and G, was isolated in Vietnam and Laos. The most recent genotype J was identified in the Ryukyu islands in Japan and this genotype has a relationship between gibon/orangutan genotypes and human genotype C. In this review, HBV genotypes and subgenotypes, their geographic distributions and clinical aspects were overviewed.