120% ± 0.005%. However, this number varied according to the considered amino acid position. Therefore, only substitution frequencies higher than the mean maximal error rate for the corresponding amino acid position plus 2 SDs were taken into account in the analysis. Plasmids were tested in triplicate at different dilutions ranging from selleck chemical 5 × 103 to 108 copies/mL. No effect of the

DNA amount on UDPS results was observed (data not shown). UDPS was then applied to serum samples taken at baseline and frequently during therapy, representing a total of 119 serial samples from 7 patients who developed resistance to adefovir monotherapy (15-24

samples per patient). Approximately 480,000 sequences (111 Mbp) were generated, with 4,010 ± 843 sequences per sample and a mean length of 382 ± 31 nucleotides (nt) after eliminating excessively short sequences (≤50 nt). Overall, 10.2% of the generated sequences were eliminated by the software because of inadequate quality. Table 1 shows the prevalence of amino acid substitutions known to confer HBV resistance to nucleoside/nucleotide analogs detected by UDPS at baseline in the 7 patients. Five samples were found to harbor rtA181V/T substitutions, SCH727965 manufacturer one harbored the rtN236T substitution, and two harbored rtM204V/I substitutions. No substitutions known to improve the fitness of rtM204V/I variants in

the presence of lamivudine, telbivudine, or entecavir (rtV173L and rtL180M) were found in baseline samples. One sample harbored the rtT184S/A/I/L substitution and none medchemexpress harbored the rtR202G substitution; both these substitutions are known to confer full resistance to entecavir when associated with rtM204V/I and rtL180M. Table 1 also shows the prevalence of amino acid substitutions known to confer HBV resistance to nucleoside/nucleotide analogs detected by UDPS in the two comparator groups described in the Patients and Methods section. Among the 5 HBeAg-positive patients who seroconverted and maintained undetectable HBV DNA levels after adefovir therapy, 2 were found to harbor rtA181V/T substitutions at baseline, whereas none harbored the rtN236T substitution; 2 harbored rtM204V/I substitutions, including 1 in whom it represented nearly 10% of the viral quasispecies and was associated with an rtL180M substitution, suggesting earlier exposure to lamivudine; rtT184S/A/I/L and rtR202G substitutions were found in 1 and 1 patient, respectively.