Clinical characteristics of hepatitis B virus genotypes

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Hepatitis B virus (HBV) isolated in1965 by Dr. Blumberg et al. In 1988, HBV was firstly classified into four genotypes, A-D, by a nucleotide sequence difference greater 8 % in the entire genome, and designated by A to D. At present, there are seven genotypes of HBV by molecular evolutionary analysis and an eight, genotype H, is now on the horizon.HBV genotype A localize mainly in Europe, North Africa, and North and South America. HBV genotype B and C are very common in Asia. HBV genotype D is also mainly in the Mediterranean, the Middle and, Near East and South American countries. HBV genotype E is prevalent in West Africa. HBV genotype F and H localize in Central, and South America. HBV genotype G is still unknown, because of recently identified in 2000.The mutation for a stop codon in the precore region(G1896A)for stopping the translation of HBeAg is prohibited in HBV genomes of genotype A, as well as genotype C and F, because they have C at position 1858 that makes a Watson-Crick pair with G at position 1896. So, seroconversion to antibody to HBeAg is forbidden or delayed in individuals who infected the genotypes. Evidence is accumulating as regards the influence of HBV genotypes on the progression of chronic hepatitis B and response to antiviral therapies. These data strongly indicate that HBV genotypes play a big role of the difference of the response to antiviral therapy and that of clinical characteristics in each different HBV genotype infected carriers.10.