Analysis of hepatitis B genotype changes in chronic hepatitis B infection: Influence of antiviral therapy

Background/Aims: The frequency of mixed hepatitis B virus (HBV) genotypes in chronic HBV (CHB) and genotype changes during natural disease evolution and as a result of antiviral therapy were investigated. Methods: Serum samples from 103 CHB patients were included in a cross-sectional study. Longitudinal study of HBV genotypes was performed in 22 patients, 17 of them under antiviral therapy (lamivudine and/or adefovir). HBV genotyping was done by the INNO-LiPA HBV assay. Results: Genotypes observed in the cross-sectional study: A 32% of cases, D 42%, C 2%, F 2%, and mixed genotypes 22% (mainly A/D, followed by A/G). Genotype G was found in 7% of patients, always combined with other genotypes. In the longitudinal study, genotype changes were observed only in treated patients (9 cases). Genotype A strains were positively selected in 6 of them, mainly as mixed AID. In 6 patients, selection coincided with a decrease in HBV-DNA levels. Conclusions: A high frequency of mixed HBV genotypes was observed in our setting. Selection of genotype A strains during treatment is likely an indication that sensitivity to therapy differs between genotypes A and D. The absence of changes in untreated patients suggests that HBV genotype is stable without external factors. (C) 2008 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.