Trofile Co-Receptor Tropism Assay
Use
The Trofile Co-Receptor Tropism Assay is used to detect HIV-1 coreceptor tropism, helping determine eligibility for CCR5 antagonist therapies, such as maraviroc (Selzentry). This information is critical because different HIV-1 subtypes utilize different coreceptors (CCR5 or CXCR4) for cell entry, impacting treatment efficacy. This assay is particularly valuable for tailoring HIV treatment strategies to enhance patient outcomes by identifying suitable candidates for CCR5 antagonist therapy based on their specific HIV-1 tropism.
Special Instructions
The test requires specific specimen collection and handling procedures. Blood should be drawn in PPT or lavender-top (EDTA) tubes; plasma must be transferred to a plastic vial and frozen immediately to avoid processing delays. It is important to submit separate frozen specimens for each test requested to prevent delays in turnaround time. For optimal results, the most recent viral load should be confirmed within two weeks prior to submission for testing at Monogram, especially for patients with viral loads greater than or equal to 1,000 copies/mL.
Limitations
The Trofile assay does not determine non-reportable tropism due to viral load less than 1,000 copies/mL, compromised sample handling, or reduced viral robustness. It only assesses HIV entry contra CCR5 and CXCR4 receptors on CD4+ cells using the complete gp160 coding sequence of the HIV-1 envelope protein. Possible interference in the assay can arise from inadequate sample collection or improper handling, affecting the assay's sensitivity at low viral loads. Results may vary in the presence of mixed-tropic HIV populations.
New York Approved
Methodology
PCR-based (PCR)
Biomarkers
LOINC Codes
- 57182-8
- 57182-8
Result Turnaround Time
29-39 days
Related Documents
For more information, please review the documents below
Specimen
Plasma
Volume
3 mL
Minimum Volume
1 mL
Container
Lavender-top (EDTA) tube or plasma preparation tube (PPT)
Collection Instructions
Draw blood in PPT or lavender-top (EDTA) tubes. Centrifuge within six hours, remove plasma and transfer to a screw-capped plastic vial. Freeze and send specimen frozen.
Storage Instructions
Send specimen frozen.
Causes for Rejection
PPT not centrifuged; insufficient volume; heparinized plasma; non frozen specimens
Stability Requirements
| Temperature | Period |
|---|---|
| Frozen | 14 days |