Implications of genetic variation on the pathogenesis of hepatitis B virus infection
It is now well established that sequence variation of hepatitis B virus (HBV) occurs worldwide. Although variants have been classified into subtypes by means of antigenic specificities of the surface proteins, it may be that HBV can be better classified into genotypes by means of percentage nucleotide difference. HBV can be classified into at least four genotypes based on a divergence of >7% at the nucleotide level  and it is clear that, based on this definition, other genotypes will be described in the future. Whether genotyping in this fashion is a satisfactory method of classifying HBV, and whether this has any relevance to the pathogenesis of the liver disease, infectivity or spread remains to be seen. Subtypes, defined by antigens associated with specific amino acid changes, are distributed geographically and have no apparent ink with disease. Whether one subtype can infect a person previously infected with a different subtype is unclear; at least, it would seem to be quite uncommon.
KeywordsFulminant Hepatitis HBeAg Positive Patient preC Mutant Core Epitope HBeAg Positive Group
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