RESUMO
Adefovir dipivoxil has been used alone or together with lamivudine to suppress lamivudine-resistant hepatitis B virus (HBV). However, the dynamics of HBV populations under different selection pressures and their impact on treatment outcome are poorly understood. Pyrosequencing was applied to quantify longitudinally the evolution of wild type and lamivudine/adefovir-resistant HBV. Eight patients, with lamivudine-resistant HBV, were randomized to receive adefovir monotherapy or adefovir/lamivudine combination therapy for a median of 79 and 71 weeks, respectively. Pyrosequencing proved highly sensitive with a lower limit of quantitation of minor HBV populations of 2% irrespective of viraemia levels. Adefovir/lamivudine treatment resulted in greater viraemia reduction than adefovir monotherapy. During combination therapy, lamivudine-resistant HBV populations (codons 180 and 204) remained dominant (>90%) and no adefovir-resistance developed. During adefovir monotherapy, reversion to wild-type HBV was detected in two patients with one patient accumulating rapidly adefovir-resistant HBV along with increased viraemia. In conclusion, the dynamics of drug-resistant HBV strains vary under different selection pressures which have a significant impact on the success of rescue therapy, as well as for the selection of new mutations. The use of techniques such as Pyrosequencing provides an evidence-based approach for successful management of drug-resistant HBV.
Assuntos
Adenina/análogos & derivados , Antivirais/uso terapêutico , Farmacorresistência Viral , Vírus da Hepatite B/efeitos dos fármacos , Hepatite B Crônica/tratamento farmacológico , Lamivudina/uso terapêutico , Organofosfonatos/uso terapêutico , Adenina/uso terapêutico , Adulto , Antivirais/farmacologia , Quimioterapia Combinada , Feminino , Vírus da Hepatite B/genética , Vírus da Hepatite B/fisiologia , Hepatite B Crônica/genética , Hepatite B Crônica/virologia , Humanos , Lamivudina/farmacologia , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Inibidores da Transcriptase Reversa/farmacologia , Inibidores da Transcriptase Reversa/uso terapêuticoRESUMO
BACKGROUND/AIMS: To gain understanding of inter-individual differences of treatment response in hepatitis C virus genotype 1 (HCV-G1) patients, we investigated simultaneously the early HCV kinetics and virus-specific T-cell reactivity. METHODS: Thirty, treatment-naïve HCV-G1 patients received peginterferon-alfa2a 180 microg/week plus ribavirin 1000-1200 mg/day, with blood samples collected prospectively at protocol time-points. HCV RNA was quantitated with a TaqMan assay with mathematical modelling of HCV decay. Virus-specific CD4+/CD8+ T-cells were enumerated by Elispot assays. RESULTS: HCV kinetic analysis identified two subgroups: fast (18/30) and slow (12/30) treatment-responders. Although these subgroups did not differ in any baseline characteristics, fast responders (FR) showed greater antiviral efficacy (epsilon) than slow responders (SR) (84.5+/-3.2 vs. 65.2+/-7.0%, P=0.002), and a higher rate of infected cell loss (delta) (0.56+/-0.2 vs. 0.04+/-0.02, P=0.038). The viral load drop (baseline to treatment week 4) was higher in FR vs. SR group (3.5+/-1.1 vs. 1.4+/-0.6 log10IU/mL, P<0.001). T-cell reactivity to HCV increased only in FR (after the loss of viraemia), but not in SR patients. CONCLUSIONS: Assessment of early viral and T-cell kinetics during treatment reveals marked differences amongst HCV-G1 patients and may provide a basis for treatment individualization. Enhancement of antiviral T-cell reactivity requires rapid viraemia clearance, rather than immunostimulation alone.