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

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 > 1000 copies /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.

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

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.

Reporting

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

References

LAB-SD-097, HIV Baseline Genotyping

LAB-SD-107 New HLA-B*57:01,LAB-SD-082 New Proviral HIV DNA Tropism (V3) Assay