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Antimicrobial Agents and Chemotherapy, July 1999, p. 1600-1608, Vol. 43, No. 7
PHLS Antiviral Susceptibility Reference Unit,
Received 30 November 1998/Returned for modification 22 February
1999/Accepted 22 April 1999
Very rapid amplification of DNA by PCR in small volumes can be
continuously monitored by the detection of the binding of probes with a
rapid cycler with built-in fluorometric detection. Primers were
designed to amplify approximately 100 bp of the polymerase gene of
hepatitis B virus (HBV) spanning codon 550, where mutations associated
with resistance to lamivudine invariably occur. Four hybridization
probes were synthesized: one was 3' labelled with fluorescein and
hybridized upstream of codon 550. The others were 5' labelled with Cy5
and 3' labelled with biotin and spanned codon 550. The Cy5-labelled
oligonucleotides contained either wild-type (ATG) or mutant (GTG or
ATT) sequences. A Cy5-labelled probe and either the
fluorescein-labelled probe or Sybr Green 1 (a compound that fluoresces
when bound to double-stranded DNA) were included in each PCR. After
completion of the amplification by using a LightCycler (Idaho
Technology), the temperature at which the Cy5 probe melted from the
product was determined in a melt program that took ca. 3 min. Pre- and
posttreatment samples from eight patients (five chronic and three
transplant) who failed lamivudine treatment were amplified, and the
presence of mutations in codon 550 was determined by ABI sequencing and
by using the LightCycler; in some cases PCR products were also cloned,
and multiple clones were sequenced. Concordant results were obtained in
all cases. We found the LightCycler to be better at resolving the
sequences of genomic mixtures; for example, two samples showed a
sequence at codon 550 of (A/G)T(G/T), which was found by fluorimetry to be mixtures of GTG and ATT but no ATG, and this finding was confirmed by the sequencing of clones. However, this approach was not more sensitive than population sequencing for the detection of the presence of mixtures. Overall, this pilot study has demonstrated an
approach that could be an extremely rapid and economical method for the
detection of lamivudine resistance-associated mutations in HBV.
0066-4804/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Use of Real-Time PCR and Fluorimetry To Detect
Lamivudine Resistance-Associated Mutations in Hepatitis B
Virus
*
Corresponding author. Mailing address: PHLS Antiviral
Susceptibility Reference Unit, Division of Immunity and Infection,
University of Birmingham Medical School, Birmingham B15 2TT, United
Kingdom. Phone: 44-121-414-6972. Fax: 44-121-414-3454. E-mail:
p.cane{at}bham.ac.uk.
Antimicrobial Agents and Chemotherapy, July 1999, p. 1600-1608, Vol. 43, No. 7
0066-4804/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
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