HIV – Diagnostic Serology

Testing Indications

If ordering as part of a Prenatal Serology work-up, see Prenatal – Serology.

Specimen Collection and Handling

Specimen Requirements

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

HIV

Serum

1.0 ml

Blood, clotted - vacutainer tubes (SST)1

HIV

Blood

3.5.0 ml

Blood, clotted - vacutainer tubes (SST)1

Submission and Collection Notes

1

For testing all Hepatitis markers, HIV, HTLV, Syphilis and Rubella, you only are required to submit two FULL red top or serum separator tubes (SST).

2

Do NOT submit glass tubes.

Limitations

Haemolysed, icteric, lipemic or microbially contaminated sera or plasma are not recommended for testing.

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.

Special Instructions

Centrifuge if using SST. Place specimen in biohazard bag and seal. Specimens should be stored at 2-8°C following collection and shipped to PHOL on ice packs.

Specimens may be stored on or off the clot or red blood cells for up to 7 days at 2-8°C. If testing will be delayed more than 7 days, remove serum or plasma from the clot and store frozen at -20°C or colder.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

HIV diagnostic serology testing is performed daily Monday to Friday.

Turnaround time is up to 3 days for non-reactive samples and up to 6 days for reactive samples from receipt by PHO laboratory.

Stat and Critical Samples Testing

HIV Testing on ‘Source Patient’ for Needlestick/Occupational Exposure if warranted

Reporting

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

Specimens that are positive for HIV are to be reported to the Medical Officer of Health as per Health Protection and Promotion Act.

Test Methods

HIV diagnostic serology specimens are screened for HIV using a chemiluminescent micro-particle immunoassay (CMIA) for the simultaneous qualitative detection of HIV p24Ag and antibodies to Human immunodeficiency virus type 1 and/or type 2 (HIV-1/HIV-2) in human serum or plasma.

If the CMIA screening test is negative, the specimen is reported as “HIV antibody-Non-Reactive” and the report is finalized.

If the CMIA test is positive or indeterminate, the specimen is tested using the Geenius TM HIV1/2 Differential assay.

The Geenius TM HIV1/2 Differential assay is an immunochromatographic test for the confirmation and differentiation of antibodies to HIV Type 1 (HIV-1, Group M and O) and Type 2 (HIV-2) in serum or plasma samples. 

CMIA positive samples that are confirmed positive by the Geenius TM HIV1/2 Differential assay are reported as either “Positive for HIV 1” or “Positive for HIV 2 antibody” depending on the antibodies detected. CMIA positive samples that are Negative or Indeterminate by Geenius TM HIV1/2 Differential assay are screened for P24 Ag using an ELFA technique (Enzyme Linked Fluorescent Assay) for the detection of HIV type 1 p24 antigen  in human serum or plasma. Samples that are positive for P24 Ag are then confirmed using an assay based on the neutralization of P24Ag.  Samples that confirm positive for P24 Ag are reported as confirmed reactive with a final interpretation of “Evidence of HIV 1 infection prior to seroconversion”. CMIA positive samples that test Negative or indeterminate on the Geenius TM HIV1/2 Differential assay and the P24 Ag assay will be reported as inconclusive for HIV. Patients whose specimen is reported as inconclusive should have a follow up specimen submitted for repeat testing at least 4 weeks after collection of first specimen.

 

Prenatal HIV testing

For Prenatal HIV testing see HIV-Prenatal Serology

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Contact Laboratory Customer Service

Laboratory Services

customerservicecentre@oahpp.ca

Updated 17 April 2019