HBV genotypic drug resistance testing
First time users
If you are using the service for the first time please contact the Unit manager, Dr Steve Kaye, to discuss your requirements and answer any questions you may have.
+44 (0)20 7594 3917
FAO Dr Steve Kaye
Molecular Diagnostic Unit,
Imperial College London
4th Floor, Medical School Building
St. Mary’s Hospital
London W2 1PG
Scope of the tests
Decreased susceptibility of HBV to antiretroviral drugs (phenotypic drug resistance) is usually associated with sequences changes in the viral genome (genotypic drug resistance). Detection of these mutations in the viral genome can be used to accurately predict the susceptibility of the virus to currently licensed antiviral drugs used to treat HBV infection and thus can be used to optimise the use of antiviral treatment on an individual patient basis. Currently, the Molecular Diagnostics Unit (MDU) routinely offers sequencing of the polymerase gene of HIV-1 of plasma viral DNA. Samples with any viral load greater than 50 HBV DNA copies/ml plasma can be analysed.
The test generates a sequence covering the whole of the HBV polymerase gene (344 codons). The method is a fully validated in-house method. A summary of the validation is available from the Unit Manager.
The raw data produced by the resistance assay is an edited nucleotide sequence. To generate a usable report this sequence is submitted to an online algorithm hosted by the Max Planck Institute. The geno2pheno interpretation is pasted into the final MDU report. If the user requires the sequence file (“FASTA” file) or the raw data chromatograms these can be supplied by arrangement with the Unit Manager.
We aim to issue reports within two weeks of receiving a sample. However, as we offer a bespoke service and make rigorous efforts to produce a result from any sample, turnaround times may be extended if repeat testing is required.
If you are unhappy with the service provided by MDU or if you wish to make suggestions on how our service can be improved, please contact the Unit Manager, Steve Kaye (firstname.lastname@example.org).
For routine testing, the required sample is either two 1ml vials of frozen plasma, prepared by your local virology or microbiology department or two 4.5ml EDTA Vacutainers of whole blood. If plasma is prepared locally you should contact the laboratory for their sample requirements but the anticoagulant must be EDTA and the plasma should be stored at -70°C or lower prior to shipping. Each sample must be accompanied by a request form. This can either be the form provided by MDU (HBV request form Word Document) or your own form. If it is the latter it must contain the following details: patient clinic number (not the patient’s name), date of birth, sample date and most recent virus load. Other details such as reason for test, current and previous antiviral therapy are useful but not essential.
Whole blood samples should be couriered to MDU the same day if possible. However, MDU closes at 17:00, so if a sample cannot be guaranteed to arrive before that time (from a late afternoon or evening clinic) it can be kept in the refrigerator (not freezer) and shipped the next day, or can be shipped the following Monday if taken late on Friday. Plasma samples can be shipped at ambient temperature if they are guaranteed to arrive the next day.