Hepatitis B virus genotypes: Do they play a role in the outcome of HBV infection?

✍ Scribed by Scott K. Fung; Anna S. F. Lok

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 370 KB
• Volume: 40
• Category: Article
• ISSN: 0270-9139
• DOI: 10.1002/hep.1840400407

✦ Synopsis

H epatitis B virus (HBV) has been classified into 8 genotypes (A-H) based on an intergroup divergence of 8% or more in the complete nucleotide sequence.'J Figure illustrates the geographic distribution of HBV genotypes, but existing information is incomplete, as data in many parts of the world are not available or are based on very small numbers of patients studied. Additionally, the distribution of HBV genotypes may vary with time and with population migration, as demonstrated in a recent study in the United States.3 Furthermore, subtypes have now been identified within some genotypes.

In the 2.5 years since our last editorial,' there has been an explosion of knowledge in the literature on the epidemiology of HBV genotypes, and their association with hepatitis B e antigen (HBeAg) seroconversion, activity of liver disease, and treatment response.

HBV Genotypes, HBeAg Seroconversion and

Outcome of Chronic HBV Infection

Most of the information on the clinical significance of HBV genotypes has been based on studies of patients with chronic HBV infection in Asia. Because of the preponderance of genotypes B and C in Asian countries, the studies are restricted to comparisons of patients with these two genotypes. Nevertheless, such comparisons provide very important information on the relation between HBV genotype B and C and the rate of progression of liver disease, since the age at the onset of infection is presumed to be the same (perinatal period) in the vast majority of patients. These studies clearly showed that compared to genotype C, HBV genotype B is associated with spontaneous HBeAg seroconversion at a younger age, less active liver disease, and a slower rate of progression to cirrhosis-3 Some studies also found that genotype B patients are less likely to have hepatitis flares and more likely to remain in remission after HBeAg seroc~nversion.~ Most studies, in-Abbreviations: HBK hepatitis B virus; HCC, hepatocellular carcinoma