Quasispecies analysis and in vitro susceptibility of HBV strains isolated from HIV-HBV-coinfected patients with delayed response to tenofovir.

BACKGROUND: Among 141 HIV-HBV-coinfected patients treated with tenofovir in our centre, 87% were good-responders to therapy. Seven patients showed a delayed response to tenofovir. The present study was performed to evaluate the quasispecies variability and the in vitro drug susceptibility to approved antiviral drugs of HBV genomes directly isolated from patients' sera. METHODS: After purification of DNA from serum samples, full-length HBV DNA was amplified by PCR, cloned and sequenced. Drug sensitivity of HBV strains isolated from four delayed responders and five good-responders was assessed and compared to a wild-type HBV strain after transfection of the full genome into HepG2 cells. RESULTS: Delayed responders, compared with good responders, showed a higher incidence of lamivudine-resistant mutations (71% and 35%, respectively; P=0.021) and a higher proportion of HBV genotype G (57% versus 16%, respectively; P=0.026). Clonal analysis demonstrated a higher variability of HBV quasispecies in delayed reponders than in good responders. In vitro analysis showed a lower efficacy of adefovir and tenofovir in delayed reponders. Furthermore, HBV genotype G strains showed a mild to weak susceptibility to tenofovir. CONCLUSIONS: The reason for the slow decline in HBV DNA level observed during therapy in delayed responders is not clear. Delayed responders showed higher quasispecies variability, a higher proportion of HBV genotype G and a mild in vitro decreased susceptibility to tenofovir and adefovir. A combination of these factors in heavily treatment-experienced HIV-infected patients could explain the lower tenofovir activity. These patients must be closely monitored to prevent prospective emergence of resistance to approved antiviral drugs.

Long-term outcome of primary non-responders to tenofovir therapy in HIV/HBV-co-infected patients: impact of HBV genotype G.

AIM: To evaluate the early virological response (EVR) to combined tenofovir-lamivudine or emtricitabine regimen in HBV/HIV-co-infected patients and the long-term efficacy of tenofovir. METHODS: In this retrospective monocentric study, among the 166 HIV/HBV-co-infected patients regularly followed from 2003 to 2008 at Bichat Claude Bernard Hospital, 61 patients had received, either de novo combination therapy with tenofovir and lamivudine or emtricitabine (group I, n = 15) or add-on tenofovir to lamivudine therapy (group II, n = 46). The HBV polymerase region was sequenced and analysed for all patients with available samples. RESULTS: All 15 group I patients achieved EVR vs 32 (82%) of group II patients (P = 0.15). Seven adherent group II patients met criteria for primary non-response, but achieved delayed response (DR) to therapy. In these seven patients, when compared with the 39 group II patients, there was a trend to longer duration of lamivudine pre-treatment and to higher rate of lamivudine-resistant mutants; and HBV genotype-G proportion was higher (P = 0.026). No virological breakthrough occurred after a median of 46 months follow up. CONCLUSION: In these HBV/HIV-co-infected patients, first-line HBV therapy with tenofovir and emtricitabine or lamivudine was associated with EVR. However, DR to tenofovir was observed in 15% of patients who added tenofovir to lamivudine therapy, of whom four of seven (57%) had genotype G-HBV infection. No resistance was evidenced after 46 months of therapy even in patients with DR to tenofovir. At last, a good renal safety profile of TDF was observed after a median follow-up of 4 years of therapy.