HBV mutations and their clinical significance.

PURPOSE: The launch of the vaccine against HBV in 1983 significantly reduced the number of HBV infections in the world. But there still remain a large group of people with chronic hepatitis B who were infected before beginning of vaccination programs or in whom the vaccine was - for various reasons - ineffective. Current therapy of HBV infection based on PEG-IFN α-2a or nucleotide/nucleoside analogues does not guarantee sustained virologic response in the large majority of chronically infected persons. Treatment with some nucleoside analogues is associated with mutations and subsequent selection of resistant strains resulting with therapeutic failure, risk of cross-resistance to other drugs and finally selection of mutants with oncogenic properties.