Herpes Simplex Virus and Varicella Zoster Virus

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 information on molecular testing for both Herpes Simplex Viruses and Varicella Zoster Virus at Public Health Ontario’s (PHO) laboratory.

This page is for information specific to molecular testing. For information regarding other testing options, refer to the following PHO webpages:

Updates

Combined HSV PCR TIS and VZV PCR TIS into one TIS document
Added testing information for HSV anti-viral resistance genotyping and VZV genotyping

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

Testing Indications

Polymerase chain reaction (PCR) testing for HSV and VZV is indicated for patients with compatible signs and presentations.

For patients suspected of having anti-viral resistant Herpes Simplex Virus-1 (HSV-1) or Herpes Simplex-2 (HSV-2), characterized by no improvement (or relapse) in HSV-1 or HSV-2 lesions, HSV anti-viral resistance genotyping is available at the National Microbiology Laboratory (NML) in Winnipeg. Drug resistant HSV is more commonly isolated in immunocompromised patients.

Varicella genotyping is available at NML to differentiate between wild type and vaccine strain Varicella for those who have been immunized with attenuated VZV vaccine within the last month or when virus strain reactivation is suspected.

Acceptance/Rejection Criteria

Check the expiry dates of both the collection swabs and transport media (tube), as specimens collected and received in incorrect containers or expired kits will be rejected for testing. In addition, specimens must meet the Criteria for Acceptance of Patient Specimens.

Specimen Collection and Handling

Specimen Requirements

Test Requested	Required Requisition(s)	Specimen Type	Minimum Volume	Collection Kit
Herpes Simplex Virus (HSV)	General Test Requisition	Swab of lesion/vesicular fluid	0.5ml	Virus Culture Collection Kit Order #390081
Varicella Zoster (VZV)	General Test Requisition	Swab of lesion/vesicular fluid	0.5ml	Virus Culture Collection Kit Order #390081
HSV resistance testing²	General Test Requisition	Swab of lesion/vesicular fluid (1ml); Plasma (1ml); Cerebral Spinal Fluid – CSF (0.6ml); Viral culture (1ml)	0.5ml	Virus Culture Collection Kit Order #390081
VZV genotyping³VZV resistance testing⁴	General Test Requisition	Swab of lesion/vesicular fluid (1ml); Whole blood (1ml) Plasma (1ml); Cerebral Spinal Fluid – CSF (0.6ml); Viral culture (1ml)	0.5ml	Virus Culture Collection Kit Order #390081
HSV/VZV	General Test Requisition	Cerebral Spinal Fluid – CSF	1.0 ml	Sterile container

Submission and Collection Notes

Complete all fields of the General Test Requisition Form. Ensure the following fields are completed if diagnostic testing is requested:

Patient setting
Symptoms (indicate all symptoms) and symptom onset
Specimen source (e.g. lesion)
Requesting healthcare provider’s CPSO#,
Complete mailing address, telephone, and fax number
Patient’s full name and address, date of birth, health card number (must match the specimen label)

Failure to do so may result in rejection or testing delay.

HSV resistance testing is referred out to National Microbiology Laboratory (NML) when clinically indicated. Refer to NML guidelines – Viral Exanthemata and STDs-Viral STI, Polyoma and Herpesvirus unit

VZV genotyping is referred out to the National Microbiology Laboratory (NML). Specimens must be confirmed to be HSV_VZV_PCR positive before sending. Genotyping (Wild-Type vs. Vaccine Strain Differentiation)

VZV resistance testing requires NML consultation and pre-approval by a PHO Microbiologist

Specimens that are not listed on the table will require pre-approval by PHO microbiologist, contact PHO’s Laboratory Customer Service Centre at 416-235-6556 or 1-877-604-4567 before submission. Critical samples may be considered for testing and will be reported with disclaimer.

Storage and Transport

Specimens should be stored at 2-8°C following collection and shipped refrigerated to PHO on ice packs; if transport is delayed for more than 72 hours, stored at -80°C and ship on dry ice.

All clinical specimens must be shipped in accordance to the Transportation of Dangerous Good Act

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Herpes simplex/ Varicella Viruses polymerase chain reaction (HSV_VZV_PCR) test is performed daily, Monday to Friday, at PHO’s laboratory, Toronto sites, Hamilton and Kingston.

The TAT are listed in the table below.

Test	Turnaround Time (TAT)
HSV-VZV-PCR testing	Up to 4 business days from receipt at the PHO’s laboratory
Herpes Simplex Virus (HSV-1 & HSV-2) anti-viral resistance genotyping	Up to 10 calendar days upon receipt at NML
VZV genotyping	Up to 7 calendar days upon receipt at NML

STAT and Critical Specimens Testing

STAT testing is not available at Public Health Ontario’s laboratory

Test Methods

The HSV-VZV polymerase chain reaction (PCR) test is a Laboratory Developed Test (LDT) validated at PHO’s Laboratory. It is a multiplex assay that detects – Herpes Simplex Type 1 (HSV-1); Herpes Simplex Type 2 (HSV-2) and Varicella Zoster Virus (VZV).

PHO’s laboratory will issue report with all 3 target viruses results regardless of which targets has been requested on the requisition.

Tests perform at National Microbiology Laboratory (NML):
Herpes Simplex Virus (HSV-1 & HSV-2) anti-viral resistance genotyping is referred out to National Medical Microbiology (NML) when clinically indicated and requested on requisition.

VZV genotyping differentiates between the wild type and vaccine strains of VZV. It is referred out to NML when requested.

VZV resistance testing is referred out to NML when clinically indicated.

Interpretation

Results will be reported as DETECTED/NOT DETECTED/INDETERMINATE for HSV_VZV_PCR analysis at PHO’s Laboratory on all 3 viruses: HSV 1, HSV 2 and VZV upon each sample request:

An indeterminate PCR test result may be due to a low level of target genetic material in the specimen, inadequate specimen content, or a non-specific signal. Suggest to resubmit another specimen for testing if clinically indicated
This result must be interpreted within the context of the clinical history and epidemiological information.

A negative result does NOT exclude the possible presence of HSV/VZV virus.

Reporting

Results are reported to the physician, authorized health care provider (General O. Reg 45/22, s.18) or submitter as indicated on the requisition.

Specimens that are positive for Varicella Zoster virus are reported to the Medical Officer of Health as per Health Protection and Promotion Act.

Specimens that are positive for Herpes Simplex from sterile sites (e.g. CSF) are reported to the Medical Officer of Health as per Health Protection and Promotion Act.