• entecavir;
  • resistance;
  • R192PR mutation;
  • TDF resistance


Nucleos(t)ide analogs such as tenofovir, lamivudine, or emtricitabine are active against both HBV and HIV. Tenofovir confers potent and durable HBV-DNA suppression but the best strategy in case of resistance of HBV to tenofovir remains unknown. A case of a 22-year-old patient with co-infection with HBV and HIV transmitted perinatally is reported. After prolonged and intermittent treatment of HIV with lamivudine and tenofovir, HBV became resistant to lamivudine. Subsequently, clinical resistance to tenofovir occurred, manifesting as HBV-DNA breakthrough. The non-compliance was reasonable excluded and HIV-RNA remained constantly suppressed. Entecavir (1 mg daily) was added and the combination therapy resulted in a rapid and continuous suppression of HBV-DNA for over 12 months. The treatment was well-tolerated and safe. No known mutations, such as rtA181T/V associated with rtN236T or A194T that are associated with reduced susceptibility or resistance to tenofovir were detected. However, a unique and complex HBV substitution pattern was found: with a development of rtR192PR mutation at the time of virological failure. Adding entecavir to failing therapy with tenofovir and emtricitabine was feasible, well-tolerated and resulted in virological success. The rtR192PR, which is located in the B domain near the rtA194T, occurring in a context of a very complex substitutions patterns, might be associated with resistance to tenofovir. J. Med. Virol. 84:1340–1343, 2012. © 2012 Wiley Periodicals, Inc.