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Detection of mixed populations of wild-type andYMDD hepatitis B... » Isaúde
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BMC microbiology [electronic resource]
2012-06-07 03:35:04

Detection of mixed populations of wild-type andYMDD hepatitis B variants by pyrosequencing inacutely and chronically infected patients

Descrição: Background:Lamivudine (LAM) is associated with the highest known rate of resistance mutations amongnucleotide analogs used to treat chronic hepatitis B virus (HBV) infection. Despite this, LAMcontinues in widespread use, especially in combination therapies. The primary LAMresistance mutation (rtM204V/I) occurs in the YMDD motif of HBV polymerase. The aim ofthis study was to characterize Brazilian HBV isolates from acute and chronic cases by directsequencing, and to identify HBV quasispecies in the YMDD motif using a pyrosequencingmethod capable of detecting single-nucleotide polymorphisms. HBV DNA from serumsamples of 20 individuals with acute HBV infection and 44 with chronic infectionundergoing antiviral therapies containing LAM were analyzed by direct sequencing andpyrosequencing methods.Results:Phylogenic analyses of direct-sequenced isolates showed the expected genotypes (A, D andF) for the Brazilian population in both acute and chronic infections. However, withingenotype A isolates, subgenotype A2 was more frequently detected in acute cases than inchronic cases (P = 0.012). As expected, none of the individuals with acute hepatitis B hadLAM-resistant isolates as a dominant virus population, whether detected by direct sequencingor pyrosequencing. However, pyrosequencing analyses showed that 45% of isolates (9/20)had minor subpopulations (4-17%) of LAM-resistant isolates. Among chronic patientsundergoing LAM treatment, YMDD mutants were frequently found as a dominant viruspopulation. In cases where wild-type virus was the dominant population, subpopulations ofYMDD variants were usually found, demonstrating the complexity of HBV quasispecies.Conclusions:YMDD variants were frequently detected as a minor population in acute HBV infection. Theoccurrence of pre-existing variants may lead to a high frequency of resistant mutants duringantiviral therapy in the chronic phase. In chronic infection, detection of YMDD variantsbefore virological or biochemical breakthrough might contribute to making better therapychoices and thus improving treatment outcome.

Identificador: doi:10.1186/1471-2180-12-96
Volume: 0
Página: 9 a

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