Danielle Colledge | PubMed Health

PubMed2006

SeqHepB: a sequence analysis program and relational database system for chronic hepatitis B.

SeqHepB is a combination of a HBV genome sequence analysis program and a relational database that houses data collected from multiple data sources. Registered users can access the sequence analysis component of SeqHepB online for rapid and detailed interrogation of HBV genomic sequences. Its main function is to determine the HBV genotype, identify key mutations associated with antiviral resistance, and identify clinically important HBV mutants. All information generated is uploaded into a database and integrated with patient medical records, pathology laboratory tests, and supplemental virology results such as in vitro drug cross-resistance values. Combined with structured query language (SQL) queries developed in the database, it is possible to extract and correlate clinical, virological, and in vitro phenotypic data rapidly and efficiently. An important component of SeqHepB is its ability to integrate mutations detected within the reverse transcriptase (RT) and locate them onto a three-dimensional (3D) model of the HBV RT that can be viewed at any angle with known antiviral drug molecules in the catalytic pocket of the enzyme. SeqHepB will enable virologists and physicians to individualise patient management, cope with the explosion of antiviral associated HBV mutations, and to conduct cross-sectional retrospective or prospective studies on HBV-infected individuals during therapy.

DNA Mutational Analysis↗

PubMed2003

Resistance to adefovir dipivoxil therapy associated with the selection of a novel mutation in the HBV polymerase.

BACKGROUND & AIMS: Adefovir dipivoxil effectively inhibits both hepatitis B virus (HBV) replication and disease activity in patients with chronic hepatitis B. Resistance to treatment was not observed in 2 recent large placebo-controlled 48-week studies with this drug. The aim of this study was to characterize adefovir resistance in a patient who developed clinical and virologic evidence of breakthrough during a 96-week course of treatment. METHODS: HBV DNA was PCR amplified and sequenced. Phenotypic studies used patient-derived HBV as well as specific mutations created by site-directed mutagenesis of a HBV/baculovirus recombinant. RESULTS: Following the commencement of treatment with adefovir dipivoxil, the patient initially responded with a 2.4 log(10) decrease in serum HBV DNA and normalization of alanine aminotransaminase levels by week 16. During the second year of treatment, however, serum HBV DNA rose progressively, eventually returning to near-pretreatment levels. This increase in viral replication was associated with a marked increase in alanine aminotransferase and mild changes in bilirubin, albumin, and prothrombin time. Comparison of pretreatment and posttreatment HBV DNA by polymerase chain reaction sequencing identified a novel asparagine to threonine mutation at residue rt236 in domain D of the HBV polymerase. In vitro testing of a laboratory strain encoding the rtN236T mutation and testing of patient-derived virus confirmed that the rtN236T substitution caused a marked reduction in susceptibility to adefovir. CONCLUSIONS: The development of this novel mutation in the HBV polymerase confers resistance to adefovir dipivoxil. The patient responded to subsequent lamivudine therapy, achieving normalization of alanine aminotransferase and a significant decrease in serum HBV DNA.

Adenine↗