HIV – PCR
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 qualitative nucleic acid test (NAT), also referred to as polymerase chain reaction (PCR), information for human immunodeficiency virus types 1 and 2 (HIV-1/-2), which are the causative agents of acquired immunodeficiency syndrome (AIDS), at Public Health Ontario (PHO). For information regarding other testing options, refer to the following PHO webpages:
- HIV – Diagnostic Serology
- HIV-1 Genotyping, Resistance, Tropism and HLA-B*57:01 Abacavir Hypersensitivity Testing
- HIV-1 Viral load
Updates
- Testing indication: Added examples of common symptoms (flu-like illness, fever, rash) in acute HIV infection.
- Acceptance/rejection criteria: Clarification that pregnant individuals with no prenatal work-up do not qualify for HIV PCR testing. These individuals should be tested using HIV diagnostic serology. Please refer to Prenatal – Serology.
- Supplies: Updated instructions for obtaining supplies.
Testing Indications
HIV-1/-2 PCR is used for the qualitative detection and differentiation of HIV-1 and HIV-2 RNA in human serum, plasma, and dried blood spots (DBS)*. HIV PCR should not be used for routine screening.
The test is intended to be used as an aid in the diagnosis of HIV specific situations:
- infants born to HIV-positive or high-risk individuals;
- high-risk pregnant individuals in labour or at delivery with unknown HIV status and potential exposure in the last 2 weeks;
- resolution of indeterminate HIV antibody result;
- diagnosis of acute infection (flu-like symptoms, fever, rash) prior to seroconversion;
- transplant patients receiving immunosuppressive drugs.
*DBS is not Health Canada-approved but has been validated by PHO for HIV PCR testing.
Routine HIV screening should be done using HIV diagnostic serology. For more information on HIV testing recommendations, refer to Ontario Guidelines for Providers Offering HIV Testing.
Acceptance/Rejection Criteria
- Unspun primary blood collection tubes will be rejected. Spun PPT and SST are acceptable.
- Plasma collected using anticoagulants other than EDTA will be rejected.
- DBS cards with spots not fully delineated with blood will be rejected.
- Donor testing is not available through PHO’s laboratory. Specimens from patients being screened as potential donors (e.g. organ, tissue, cells, fertility, etc.) should be referred to a laboratory that performs donor screening assays. Specimens received for donor screening at PHO’s laboratory will be rejected.
- Pregnant individuals with no prenatal screening do not qualify for HIV PCR testing. HIV PCR will not be tested, and HIV diagnostic serology will be performed instead. Refer to Prenatal – Serology.
- Haemolysed, icteric, lipemic or microbially contaminated sera are unacceptable for testing.
Specimen Requirements
| Test Requested | Required Requisition(s) | Specimen Type | Minimum Volume | Collection Kit |
HIV PCR |
Serum or Plasma |
750 μl or 1.2 mL if HIV serology is also requested Note: based on submitter experience, a minimum of ~3 mL of whole blood is required to yield at least 750 μL of serum or plasma |
Serum separator tubes (SST), EDTA Plasma Preparation Tubes (PPT), or EDTA blood tube |
|
HIV PCR |
DBS2 |
1 card |
Whatman 903 cards or equivalent |
Submission and Collection Notes
Specimens may be stored at 2°C to 25°C and must be centrifuged within 24 hours of collection. If using blood collection tubes without gel separators, serum or plasma must be separated and transferred to aliquot tubes immediately before sending to PHO. Spun SST or PPT can be sent to PHO, but a separated and aliquoted serum or plasma is preferred. Submitters must ensure that PHO can obtain the minimum volume of serum or plasma required to avoid testing delays or cancellation. Centrifugation should be performed according to the tube manufacturer’s instructions. Serum or plasma can be stored in secondary tubes for up to 24 hours at room temperature followed by up to 5 days at 2°C to 8°C or up to 6 weeks at ≤-20°C.
DBS cards must have at least four (4) fully delineated spots that are allowed to dry completely before submitting to PHO. DBS must be transported to PHO at room temperature in individual sealable bags containing a desiccant sachet. Appropriately prepared DBS specimens are stable at room temperature for up to 30 days. PHO does not provide supplies for DBS collection and shipping.
Supplies may be ordered from the suppliers below. The product numbers may change. Please contact the vendors directly.
- Whatman 903 Protein Saver Card
- Cytiva Lifesciences: Product no: 10534612
- Fisher Scientific Canada: Product no: 05-705-121
- VWR Canada: Product no: CA28170-017
- Liquid Tight specimen bags
- Cytiva Lifesciences: Product no: 10534321
- Fisher Scientific Canada: Product no: 0980015
- VWR Canada: Product no: CA89027-020
- Desiccants
- Cytiva Lifesciences: Product no: 10548239
- Sigma Aldrich: Product no. Z163562
Please use the dedicated HIV Serology and PCR requisition. Complete all sections of the requisition.
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.
For high-risk pregnant individuals requiring HIV PCR testing to guide infant management after delivery, submitters must indicate “high-risk mother” in the “Other (Specify)” field under “Testing indication(s)/Criteria” of the HIV Serology & PCR Test Requisition. Failure to do so may result in testing delay or rejection.
Do not submit glass tubes.
Limitations
DBS is not Health Canada-approved but has been validated by PHO to be used for HIV PCR testing.
HIV PCR only provides a qualitative result. For HIV-1 viral load, refer to the HIV-1 RNA Viral Load Test Information Sheet.
Storage and Transport
Place specimen tube in biohazard bag and seal. Place completed HIV Serology and HIV PCR Test Requisition in the pouch at the front of the biohazard bag.
Specimen tubes should be stored according to recommend storage requirements as indicated above, and should be shipped to PHO’s laboratory as soon as possible.
All clinical specimens must be shipped in accordance to the Transportation of Dangerous Good Act.
Test Frequency and Turnaround Time (TAT)
HIV-1/-2 PCR turnaround time is up to 5 business days from receipt by PHO’s laboratory. Testing is performed daily.
STAT and Critical Samples Testing
STAT HIV PCR testing is not available. Expedited testing may be considered for specific circumstances (e.g. high-risk individuals in labour who are suspected to be in the window period) in consultation with the laboratory or a PHO Microbiologist. Please contact PHO’s Laboratory Customer Service Centre at 416-235-6556 / 1-877-604-4567 or supplementalvirologylab@oahpp.ca.
Specimens that are approved for expedited testing should be packaged separately from routine specimens, clearly marked as “PRIORITY”, and handled in accordance with the Canadian Biosafety Standards, and shipped in accordance with the Transportation of Dangerous Goods Regulations. Testing will be delayed if these instructions are not followed.
Specimens for HIV PCR are tested using the Roche cobas® HIV-1/HIV-2 Qualitative assay on the cobas 5800 system. The cobas® HIV-1/HIV-2 Qualitative assay is a NAT for the qualitative detection and differentiation of HIV-1 and HIV-2 RNA in human serum, plasma, or DBS. Specimens are tested simultaneously for HIV-1 and HIV-2, individual testing cannot be requested.
Table 1: Analytical sensitivity (limit of detection) of cobas® HIV-1/HIV-2 Qualitative assay
| Specimen Type | HIV-1 | HIV-2 |
| EDTA Plasma | 12.8 copies/mL | 35.4 copies/mL |
| Serum | 12.8 copies/mL | 26.3 copies/mL |
| DBS | 255 copies/mL | 984 copies/mL |
Algorithm
HIV PCR is part of the HIV diagnostic serology algorithm. It is used to resolve negative and indeterminate HIV confirmatory antibody results. However, it can be requested as a standalone test for reasons outlined in Testing Indications. Standalone HIV PCR requests are reviewed to ensure they meet the acceptance criteria for testing.
HIV PCR will be done automatically for HIV serology requests for individuals ≤18 months of age. To help determine HIV status and guide treatment decisions, HIV PCR will be prioritized over HIV serology for these individuals.
Interpretation
All test results should be interpreted in conjunction with the patient's clinical presentation, history and other laboratory results. The following table provides possible test results :
|
Result |
Comments |
|---|---|
HIV-1 and HIV-2 RNA not detected |
Does not exclude the possibility of infection with HIV. Individuals in high-risk groups who are HIV-1 and HIV-2 RNA not detected should be retested for up to three (3) months with HIV serology following possible exposure to HIV or on presentation of symptoms compatible with HIV infection. |
HIV-1 RNA detected |
Pregnant patients and infants (less than 24 months of age) should be referred to a paediatric HIV specialist for counselling on vertical HIV transmission prevention and/or management of the newborn, and for follow-up testing. |
Invalid |
Unable to determine result due to interfering substances. Recollect and submit a new specimen for testing. |
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