HIV – PCR

Testing Indications

HIV PCR testing has been authorized by Health Canada on Clinical Trial Status (CTS). Under CTS, designated labs may use PCR to assist in the diagnosis of HIV under specific conditions:

  • Diagnosis of HIV in infants born to HIV positive mothers
  • The resolution of HIV antibody indeterminate cases
  • The diagnosis of HIV infection in individuals likely to be in a pre-antibody, sero-conversion window                                                                 
  • Other circumstances after discussion with PHO Laboratory; contact PHO Laboratory Customer Service Centre

Specimen Collection and Handling

Specimen Requirements

Test Requested Required Requisition(s) Specimen Type Minimum Volume Collection Kit

HIV-1 PCR

Whole blood collected in EDTA tubes2

400 μl (HIV PCR only) or or 2.0 ml (if requesting HIV serology and PCR testing on the same sample)

EDTA tube (lavender top)

HIV-1 PCR

Plasma3

1.1 ml (HIV PCR only) or 3.0 ml (if requesting HIV serology and PCR testing on the sample sample)

EDTA tube (lavender top)

HIV-1 PCR

Dried Blood Spot (DBS)4

4 DBS per patient sample

Dried blood spot card

HIV-2 PCR

Whole blood collected in EDTA tubes5

5.0 ml

EDTA tube (lavender top)

Submission and Collection Notes

1

For infants ≤18 months, check the box located in ‘Specimen Details’ beside HIV PCR (for infant diagnosis ≤18 months).

2

For HIV-1 PCR: the EDTA tube should be sent to PHO Laboratory on icepacks ASAP after collection. The specimen must be received at PHO Laboratory within 5 days of collection.

3

If the specimen will not be received at PHO Laboratory within 5 days of collection, centrifuge the EDTA tube and separate the plasma within 24 hours of collection. The separated plasma can be stored at 25 to 30°C for 1 day, at 2 to 8°C for up to 5 days, or at -20 to -80°C for 6 weeks.

4

Filter cards containing dried blood spots should be shipped to PHO Laboratory in individual sealable bags containing a desiccant sachet. When the sample is appropriately prepared, it will be stable at room temperature for 30 days. Do not refrigerate samples. PHOL does not provide DBS cards. Refer to LAB-SD-086 for suggested suppliers and collection instructions.

5

For HIV-2 PCR: store the specimen at room temperature and send the EDTA tube ASAP to PHO Laboratory. The specimen must be received at the National Laboratory for HIV Reference Services (NLHRS) in Winnipeg within 48 hours of collection.

Limitations

  1. ACD tubes (yellow top) or heparin tubes (green top) are not acceptable. See Specimen Requirements above for acceptable collection kits.
  2. Specimen integrity is of critical importance as contaminated specimens may cause a false positive reaction in the assay and older specimens may degrade to falsely negative results.
  3. Some divergent genetic variants of HIV may not be successfully amplified and detected by the current assay.

Preparation Prior to Transport

Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

HIV-1 PCR turnaround time is up to 10 days from receipt by PHO Laboratory. Testing is performed once or twice a week.

Specimens for HIV-2 PCR are referred to National Laboratory for HIV Reference Services (NLHRS) in Winnipeg. Turnaround time is up to 14 days from receipt by PHO Laboratory.

STAT HIV-1 PCR testing may be considered on an individual basis for specific circumstances in consultation with a PHO Microbiologist (e.g. high risk woman in labour who are suspected to be in the window period). The PHO Microbiologist can be contacted through the PHO Laboratory's Customer Service Centre at 416-235-6556 / 1-877-604-4567.

STAT samples must be shipped separately from routine specimens in a clearly marked package indicating ‘STAT’ and handled in accordance with the Canadian Biosafety Standards and shipped in accordance with the Transportation of Dangerous Goods Regulations. Failure to ship separately will delay testing.

Reporting

Results are reported to the ordering physician or health care provider as indicated on the requisition.

Test Methods

HIV 1 PCR testing is performed using a qualitative Nucleic Acid Amplification assay (based on PCR). It is a molecular technique which amplifies and detects specific HIV 1 RNA and proviral DNA in plasma, anti-coagulated whole blood and dried blood spots.

For HIV 2 PCR test method, contact NLHRS for further information:

Phone: (204)789-6523
Email: phac.nlhrs-lnsrv.aspc@canada.ca

The HIV 1/2 PCR test is only considered useful when considered together with other licensed serological markers such as HIV1/2 antigen/antibody combo screen and HIV 1/2 Differential assay. 

Interpretation

The HIV-1/-2 PCR test is only considered useful when considered together with other licensed serological markers such as the HIV antigen/antibody combo screen and HIV-1/-2 Differential assay.

The HIV-1 PCR result is reported as Detected, Not Detected, or Indeterminate.

Mis à jour le 13 mai 2021