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Virology / Serology - Virus Culture

• DHHS Virology Form #3431 (PDF, 176 KB)
• SCOPE: Guide to Services - 04/2013 (PDF, 1.3 MB)

The Virus Culture laboratory at the NC State Laboratory of Public Health (NCSLPH) is a comprehensive virology laboratory providing testing to both the public health community and the private sector.

Successful performance of virologic studies is in part dependent upon the cooperation of informed clinicians who will obtain proper specimens taken at the correct time during the patient’s illness and provide sufficient clinical information for the laboratory to select the appropriate test or tests. Virus culture employing assorted cell culture systems and molecular assays provide a mechanism for the detection and identification of many human viruses which cause a wide variety of common illnesses. The SLPH Virus Culture unit is capable of isolating and identifying most Biological Safety Level I through III viruses that can be propagated in conventional cell culture. Molecular testing (RT-PCR; NAAT) is also routinely available for some viral agents, such as influenza.

Specimen Acceptance Policy

Routine Viral Cultures:

All appropriate specimens for culture of human viruses will be accepted from both public and private providers of health care (with the exception of HSV cultures). Specimens submitted to the Virology/Serology Unit must be accompanied by a completed DHHS Virology Form #3431 (PDF, 176 KB). Please provide a complete submitter’s mailing address, physician name, and telephone number. Minimal essential patient information that must be provided includes patient’s full first and last name, either SSN or date of birth, Medicaid number, sex, onset date, specimen source, and collection date. Also provide information on the suspected infectious agent(s) and/or provide the patient’s signs and symptoms.

Specimens which, for any reason, are deemed unsuitable or inappropriate for diagnostic testing will not be tested.  Rejected specimens will be properly stored for seven days pending verbal and/or written notification of the submitter. Unless alternate arrangements are initiated by the submitter upon notification of specimen rejection, the specimen will be discarded at the end of the holding period.

HSV Cultures:

Viral culture for HSV is available only to local health departments and other state-operated health care facilities.  Specimens acceptable for HSV culture are limited to the following:

• Specimens from prenatal patients who have a suspicious lesion not previously confirmed as herpes.  Routine cultures in the absence of lesions will not be accepted.
• Specimens from patients presenting with an atypical lesion where a clinical distinction cannot be made between herpes, chancroid, and syphilis.  Cultures done simply to confirm a clinical diagnosis of herpes are not available on a routine basis.

Specimens submitted for herpes viral culture must be accompanied by a completed DHHS Virology Form #3431 (PDF, 176 KB) that includes the clinic in which the patient was seen and the specific reason for testing, i.e., differential diagnosis of an atypical lesion, lesions in pregnant women, etc. Mark herpes simplex virus as the agent requested. Failure to supply the requested clinical patient information may result in significantly delayed specimen testing and/or rejected specimens.

Specimen Collection

The source of the specimen(s) collected must be carefully matched with the virus. A chart follows which describes the virus isolation service available at the State Laboratory, the turn-around time for viral culture results, and the specimens of choice for each virus listed. Dacron-tipped, rayon-tipped, or flocked swabs with plastic or aluminum shafts are acceptable. Cotton-tipped swabs with wooden shafts are not recommended; calcium alginate swabs are not acceptable. Most specimens can be held at 4-8°C for several days before there is a significant loss of infectivity. If transport to the laboratory will be delayed for more than several days, freezing specimens to -70°C or below will preserve viral infectivity of specimens almost indefinitely. Many viruses lose infectivity rapidly when stored at -20°C or warmer. Specimens to be tested for respiratory syncytial virus (RSV), varicella-zoster virus (VZV), or cytomegalovirus (CMV) should NOT be frozen since these viruses are easily inactivated.

Please refer to SCOPE: Guide to Services (PDF, 1.3 MB) for detailed instructions for collection of samples for viral isolation from different clinical sites.

Specimen Shipping

Keep clinical specimens cold (~4º C) during transit and ensure delivery to the State Laboratory within 24-48 hours of collection. Ideally, ship specimen(s) to the State Laboratory the same day collected. Although the virus transport mailer was designed for several specimens, the cost of the transport medium is negligible and unused medium can simply be discarded. Do not delay the shipment of specimens until all the vials of transport medium are used. Place the properly identified inoculated vials of transport medium into the large conical plastic shipping tubes. If all of the transport media is not used, return the unused large conical plastic shipping tubes to maintain a tight pack and prevent breakage.

Place the two frozen ice packs into the shipping container. Place the large conical plastic tubes containing specimen(s) or tubes without specimens for a total of three tubes between the ice packs. Place the completed forms into the plastic bag and slide into the space at the narrow end of the ice packs. Replace the styrofoam lid on the box, seal the cardboard box, and attach the return pre-addressed shipping label on top of the label used to ship the kit to you. Ship the specimen to the State Laboratory by the fastest means possible.

Transport medium and refrigerated mailers are available through the NCSLPH online supply ordering system at this website. Upon receipt, open and place transport media in the refrigerator and place ice packs in freezer. DHHS Virology Form #3431 (PDF, 176 KB) may be downloaded and printed from this website.

Results Reporting and Interpretation

Turn-around time for negative cultures varies from one to six weeks. Cultures yielding virus isolates may require more time for identification of the virus, depending upon the isolate involved. Failure to isolate a virus may be the result of a number of factors, including improperly collected specimens, specimens collected at a period in the disease when the patient is not shedding virus, improperly transported specimens, or a lack of sensitivity in the system being used for isolation. Failure to isolate a virus should not rule out the virus as a cause of the clinical illness. Conversely, since people may asymptomatically carry a variety of viruses, viruses may be isolated which are unrelated to the current illness. The clinician should interpret the laboratory report in conjunction with patient history and clinical findings.

Virus Culture Service

See also:

• About Virology/Serology
• Virus Culture
• Rabies Virus
• Chlamydia/Gonorrhea
• HIV
• Hepatitis
• Syphilis
• Special Serology
• CDC Referral
• Arbovirus
• Norovirus

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