Hepatitis C – Drug Resistance 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.
Background
This page provides testing information for hepatitis C virus (HCV) drug resistance testing (DRT) available through Public Health Ontario (PHO). Testing is referred to the British Columbia Centre for Excellence (BCCfE) for analysis.
For information regarding other HCV testing options, refer to the following PHO webpages:
Updates
- Specimen type updated to plasma under Specimen Requirements, Submission and Collection Notes, Limitations, Special Instructions sections.
Testing Indications
This test is recommended for patients who are living with hepatitis C with HCV viral loads >10,000 IU/mL and, in particular, those who have failed a previous HCV therapy containing an NS3, NS5A, or NS5B inhibitor. The test is to be considered as being for Research Use Only. HCV drug resistance testing is not required to initiate therapy.
Acceptance/Rejection Criteria
- Haemolysed, icteric, lipemic or microbially contaminated plasma are not acceptable for testing.
- Improperly collected, labelled, or processed specimens will be rejected.
Specimen Requirements
| Test Requested | Required Requisition(s) | Specimen Type | Minimum Volume | Collection Kit |
HCV Drug Resistance |
Plasma3 |
2.5 ml |
EDTA Plasma Vacutainer Tube |
|
HCV Drug Resistance - Add-on request to a specimen previously submitted for HCV viral load3,4,5 |
Specimen previously submitted for viral load testing 3,4,5 |
n/a |
n/a |
Submission and Collection Notes
Complete all fields of the requisition form, including:
- Test(s) requests and indications for testing (required)
- Patient setting/population/source
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.
A minimum viral load of 10,000 (1.0E+4) IU/mL is required for plasma specimens.
Requests for HCV DRT on serum specimens will only be accepted for serum specimens that were previously sent to PHO for HCV RNA viral load testing. For serum, the minimum viral load required for HCV DRT is 1.0E+5 IU/mL. Submission of a plasma specimen specifically for HCV DRT is preferred to requests on previously submitted serum.
For requests on a previously submitted specimen, indicate on the requisition that the specimen has been previously submitted and provide the PHO Laboratory number and fax the requisition to 416-235-6194.
Limitations
HCV DRT at BCCfE is considered as being for Research Use Only.
Storage and Transport
Plasma must be separated and transferred to aliquot tubes within 24 hours of collection and before sending to PHO. Centrifugation should be performed according to the tube manufacturer’s instructions. Plasma may be stored and/or transported at 2-8°C for up to 2 days or at ≤-18°C for up to 12 weeks. If extended storage is required, plasma specimens can be frozen at ≤-60°C.
Place specimen in a biohazard bag and seal. Specimens should be stored frozen at -20°C or colder and shipped to PHO’s laboratory on dry ice in a proper shipping container.
Test Frequency and Turnaround Time (TAT)
HCV Drug Resistance Testing is sent to British Columbia Centre for Excellence (BCCfE) weekly between Monday to Wednesday.
Turnaround time is up to 21 business days from receipt by PHO.
HCV DRT is referred by PHO to BCCfE. The methodology is based on Sanger sequencing and includes identification of known mutations associated with drug resistance.
Algorithm
Specimens submitted for HCV DRT will be tested by HCV RNA viral load testing to determine if the viral load meets the minimum requirements.
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