Wild type and YMDD variant of hepatitis B virus: no difference in viral kinetics on lamivudine/tenofovir therapy in HIV-HBV co-infected patients.

Prolonged lamivudine therapy has been identified as the major risk for the development of resistance in HBV, with rates of 90% after 4 years of treatment. Tenofovir disoproxil fumarate showed activity against both wild type and lamivudine resistant HBV in HIV-HBV co-infected patients. In order to compare the efficacy of lamivudine/tenofovir treatment we investigated detailed HBV kinetics in 13 HIV-HBV co-infected patients with either wild type HBV or lamivudine resistant HBV. The viral strains in both patient groups showed a biphasic viral decline pattern. Only in the first phase of viral decay, which reflects the clearance rate of the free virus from plasma, there was a statistically significant response in favor of the wild type group. After the first phase we observed a similar viral decline till 24 weeks of both groups. This is reassuring for many pretreated co-infected patients harbouring mutant viruses.