HIV Tropism Prediction
This test is referred to another lab outside our network
This does not affect where samples are sent and where your results are issued.
This does not affect where samples are sent and where your results are issued.
Description:
EDTA blood samples for HIV tropism prediction are sent to the Antiviral Unit, UKHSA Colindale. For HIV tropism prediction from cerebrospinal fluid (CSF) or buffy coat cells for samples <1,000 copies/ml, these samples are sent to Antiviral Resistance Testing Service, UKHSA Public Health Laboratory Birmingham. Note: If sending a CSF, a concurrent HIV viral load MUST also be requested on EDTA blood. The sequencing assay covers the envelope V3 loop of the HIV-1 gp120 gene. Predicted co-receptor use categorised as: CCR5 (R5), CXCR4 (X4), dual tropic (R5/X4) or mixed tropic (R5, X4, R5/X4).
Clinical details:
HIV infects cells expressing the primary receptor CD4 and one of the chemokine receptors CCR5 or CXCR4. CCR5 antagonists, such as the anti-retroviral drug Maraviroc, inhibit replication of R5 virus. Tropism testing is essential prior to use of this drug in order to identify individuals harbouring X4 or R5/X4 variants of HIV in whom no significant virological response to Maraviroc treatment would be anticipated
Reference range:
Not applicable. Result given as predicted tropism
Synonyms or keywords:
HIV, Tropism, genotyping, Maraviroc, sequencing
Units:
Not applicable
Department:
Location:
Sample type and Volume required:
4-9ml purple-top EDTA blood (for plasma or buffy coat cells) or cerebrospinal fluid (CSF) in a sterile universal container with no additives.
Call in advance:
Yes
Turnaround time:
7 to 14 working days
Special sample instructions:
For patients with an HIV-1 viral load of <1000 copies/ml, the assay is performed on buffy coat cells and not plasma. It is therefore essential that a fresh EDTA blood is delivered directly to the laboratory for processing. Please contact the Virology laboratory in advance to ensure the sample is received and sent away immediately.
Storage and transport:
Place labelled sample in a sealed sample bag and send to Central Specimen Reception (CSR). Samples should be sent to CSR promptly as the sensitivity of assays that detect RNA/DNA depend on sample quality/integrity. Please store samples in a refrigerator if there is a delay in sending samples to CSR.
Contacts:
Infection Sciences Department at St Thomas' Hospital
020 7188 8008
St Thomas' Hospital
North Wing - 5th Floor
Westminster Bridge Road
London SE1 7EH
Core opening hours: Monday-Friday 0900-1730
North Wing - 5th Floor
Westminster Bridge Road
London SE1 7EH
Core opening hours: Monday-Friday 0900-1730
Laboratory:
Last updated: 06/10/2023
