HIV Genotyping, Resistance, Tropism and HLA-B*57:01 Abacavir Hypersensitivity Testing

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.

*Uncontrolled print copy. Valid only on day of print: 21 Nov 2024.

Testing Indications

HIV infected patients receiving antiretroviral therapy with rising plasma viral loads of greater than 250 copies/mL could benefit from drug-resistance testing to establish HIV-sensitivity to the antiretroviral drugs they are receiving.

With drug-resistance data, physicians can rationally select a new combination therapy for their patients.

HIV Drug Resistance and Integrase Resistance testing are added automatically for baseline genotyping to naïve patients considering starting antiretroviral treatment. The eligibility for HIV Baseline genotyping is when the HIV Viral Load > 250 copies /mL.

Specimen Collection and Handling

Specimen Requirements

Test Requested	Required Requisition(s)	Specimen Type	Minimum Volume	Collection Kit
HIV Drug Resistance Testing	HIV Genotyping, Resistance, Tropism and HLA-B*57:01 Abacavir Hypersensitivity Testing Requisition	Not Required^2,3
Integrase Resistance Testing	HIV Genotyping, Resistance, Tropism and HLA-B*57:01 Abacavir Hypersensitivity Testing Requisition	Not Required^2,3
Gp-41 Resistance Testing	HIV Genotyping, Resistance, Tropism and HLA-B*57:01 Abacavir Hypersensitivity Testing Requisition	Not Required^2,3
V3 Genotyping (Tropism/ CCR5)	HIV Genotyping, Resistance, Tropism and HLA-B*57:01 Abacavir Hypersensitivity Testing Requisition	Not Required^2,4
Proviral HIV DNA Tropism (V3)	HIV Genotyping, Resistance, Tropism and HLA-B*57:01 Abacavir Hypersensitivity Testing Requisition	EDTA Whole blood	5 mL EDTA whole blood	EDTA whole blood
HLA-B*57:01 Abacavir Hypersensitivity	HIV Genotyping, Resistance, Tropism and HLA-B*57:01 Abacavir Hypersensitivity Testing Requisition	EDTA Whole blood	5 mL EDTA whole blood	EDTA whole blood

Submission and Collection Notes

Fax completed Public Health Ontario laboratory HIV Genotyping, Resistance, Tropism, and HLA-B*57:01 Abacavir Hypersensitivity Testing to HIV , Toronto Public Health Ontario Laboratory at 416 235-6194 or 416 235-6197.

PHL will use the specimen submitted for HIV Viral Load testing.

Eligibility for HIV Drug Resistance, Integrase Resistance, and gp41 Resistance: HIV Viral Load must be >250 copies/mL

Eligibility for V3 Genotyping (Tropism/CCR5): HIV Viral Load must be >500 copies per mL

Storage and Transport

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

Special Instructions

EDTA whole blood must be shipped in ice packs within 24 hours of collection.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

These tests are referred to the British Columbia Centre for Excellence (BCCfE), 613-1081 Burrard St. Vancouver B.C. Samples, and are shipped weekly on Mondays.

Turnaround time is up to 21 days from receipt by the PHO laboratory

Test Methods

BCCfE uses a genotypic sequencing system that identifies mutations in the reverse transcriptase and protease genes that encode drug resistance. BCCfE uses HIV Envelope Sequencing for T-20 Resistance, HIV Integrase Sequencing for Resistance to Integrase Inhibitors and V3 Genotyping for Coreceptor Tropism. HLA-B*57:01 screening test can be ordered before the start of a therapeutic regimen containing Abacavir.