HIV-1 RNA Viral Load
Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.
Background
This page provides information for HIV-1 RNA Viral Load Testing at Public Health Ontario (PHO).
For information regarding other testing options for HIV, refer to the following PHO webpages:
Updates
- Added Testing Indications
- Updated Specimen Requirements Table
- Updated Submission and Collection Notes
Testing Indications
HIV-1 RNA viral load testing measures the amount of HIV-1 RNA in human plasma. It is intended to be used in individuals known to be HIV-1-positive to aid in treatment monitoring and prognosis.
HIV-1 RNA viral load testing is indicated in the following:
- Baseline assessment at HIV diagnosis before starting antiretroviral therapy.
- To monitor the effectiveness of and adherence to antiretroviral therapy.
- To guide decisions on resistance testing and treatment regimen changes.
HIV-1 viral load testing should not be used as a screening test for HIV-1 or as a diagnostic test to confirm the presence of HIV-1 infection.
Acceptance/Rejection Criteria
The following specimens will be rejected:
- Unspun Plasma Preparation Tube (PPT) tubes.
- HIV-1 RNA viral load requests that do NOT use the dedicated HIV-1 Viral Load Test Requisition or incompletely filled requisition.
- Unspun ethylenediaminetetraacetic acid (EDTA) whole blood tubes received beyond 24 hours from the collection.
- Specimens labelled with information that does not match with the requisition.
Specimen Requirements
| Test Requested | Required Requisition(s) | Specimen Type | Minimum Volume | Collection Kit |
HIV-1 RNA Viral Load |
EDTA Plasma |
2.5 mL |
- PPT |
Submission and Collection Notes
Specimens may be stored at 2-25°C and must be centrifuged within 24 hours of collection.
If using EDTA blood collection tubes without gel separators (e.g., pink top or lavender top), plasma must be separated and transferred to aliquot tubes immediately after centrifugation, before sending to PHO.
Spun plasma preparation tubes (PPT) can be forwarded to PHO, but a separated and aliquoted plasma is preferred. Centrifugation should be performed according to the tube manufacturer’s instructions.
Plasma can be stored and/or transported at 2-8°C for up to 6 days or at ≤ -18°C for up to 12 weeks. If extended storage is required, plasma specimens should be frozen at ≤ -60°C.
Unspun EDTA whole blood will be accepted for testing if it arrives at PHO before 2:00 p.m. on the same day they are collected, from Monday to Friday.
Label the specimen container(s) with the patient’s first and last name, date of collection, and one other unique identifier such as the patient’s date of birth or health card number. For additional information see: Criteria for Acceptance of Patient Specimens. Failure to provide this information may result in rejection or testing delay. Patient information on the specimen must match the requisition, or the specimen will be rejected.
Complete all fields on the HIV-1 Viral Load Test Requisition. Indicate treatment information and the most recent CD4+ count. For patients on treatment, provide the antiretroviral regimen by selecting the checkboxes or specify under others if not on the list. Collection information must be provided.
Limitations
Grossly haemolysed, icteric, lipemic or microbial contaminated plasma is not recommended for testing.
Storage and Transport
Place the specimen in a biohazard bag and seal. It is recommended to ship specimens for testing to PHO immediately after collection or processing to avoid delays in testing. EDTA whole blood that has not been centrifuged must be received at PHO on the same day it is collected by 2:00 p.m., Monday-Friday.
Plasma can be stored at 2-8°C for up to 6 days and shipped on ice packs. Plasma can also be frozen at ≤ -18°C for up to 12 weeks. If extended storage is required, plasma specimens should be frozen at ≤ -60°C. Frozen plasma must be shipped on dry ice.
Shipping of specimens shall be done by TDG certified individuals in accordance with TDG regulations.
Test Frequency and Turnaround Time (TAT)
HIV-1 viral load is performed daily Monday to Friday.
Turnaround time is up to 6 business days from receipt at PHO’s Laboratory.
Specimens for HIV-1 RNA viral load are tested using the Roche cobas® HIV-1 Quantitative Assay on the cobas® 8800 system. The cobas® HIV-1 assay is a nucleic acid amplification test for the quantitation of HIV-1 RNA in human plasma from HIV-1-infected individuals.
The cobas® HIV-1 RNA viral load test has a lower limit of detection of ~13.2 copies/mL and a lower limit of quantitation of 20 copies/mL.
Interpretation
Results should be interpreted in the context of the patient’s clinical presentation, risk factors, and exposure history. The table below provides a general overview of HIV-1 RNA viral load results and interpretations.
Note: The cobas® HIV-1 RNA viral load assay can detect and amplify proviral DNA, which is present in white blood cells found in the buffy coat. If the viral load result is higher than expected based on patient’s clinical presentation, submit another specimen following the recommended collection guidelines or consult with a Microbiologist at PHO. To ensure accurate results, it is crucial that specimens are collected following recommended guidelines found under the Specimen Collection and Handling. Specimens that are collected or processed outside of these guidelines will not be tested.
| Result | Interpretation | Comments |
|---|---|---|
|
Not Detected |
HIV-1 RNA not detected. |
|
|
<20 copies/mL |
HIV-1 RNA detected below the lower limit of quantitation. Unable to quantify. |
An exact value cannot be calculated as it is below the lower limit of quantitation of 20 copies/mL. |
|
20 – 10,000,000 copies/mL |
Viral load will be reported in copies/mL. |
Generally, no change in clinical management is recommended for viral loads <40 copies/mL; however, viral loads should be interpreted based on the patient’s clinical context. For further clinical guidance, consult an HIV specialist and/or refer to the following guidelines: Ontario Clinical Care Guidelines and NIH Clinical Guidelines. PHO encourages healthcare providers to reinforce messaging with patients that if their viral load is <200 copies/mL, they are considered virally suppressed and unlikely to transmit HIV to others. |
|
>10,000,000 copies/mL |
HIV-1 RNA detected above the upper limit of quantitation. Unable to quantify. |
An exact value cannot be calculated as it is above the upper limit of quantitation of 10,000,000 copies/mL. |
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