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Specimen Collection and B virus Detection

Specimen Collection

In cases of B virus exposure and infection, specimens for virus culture and serologic testing should be obtained from the exposed person and, when feasible, from the source animal. Recommendations for sample collection, storage, and shipment are available from the National B virus Resource Center at Georgia State University’s Viral Immunology Center.

This Center provides diagnostic testing, educational resources, and emergency information 24 hours a day, year round. Its diagnostic laboratories are adjacent to the research laboratories, a proximity that facilitates exchange of the most up-to-date strategies for identification of B virus infections in the natural host and in zoonotically infected humans. Antiviral research provides current drug sensitivities and treatment monitoring for zoonotic infections.

WARNING: a specimen for PCR testing should not be obtained from the wound area prior to washing the site because it could force virus more deeply into the wound, reducing the effectiveness of the cleansing protocol.

 

Virus Detection

Diligence in the recognition of possible exposures, followed by recommended first aid and rapid diagnosis of B virus infection, are the keys to controlling human B virus infection.

Diagnosis of B virus infections has been hampered by the fact that herpes simplex virus (HSV) and B virus are closely related (both members of the Alphaherpesviridae) and, as such, antibodies produced in response to either virus have substantial levels of cross-reactivity. The development of diagnostic methods that can reliably differentiate between HSV and B virus infection was an essential first step in advancing B virus detection for the National B virus Resource Center. Direct culture of B virus has been the standard for diagnosis of infection, although this testing requires a biosafety level 4 (BSL-4) containment facility to reduce the risk of exposure for laboratory workers. The specificity of B virus serologic methods has improved substantially; however, the assays rely on specimens obtained weeks after the possible exposure event and, thus, cannot be of help in making therapy decisions, which must be made soon after exposure.

The availability of PCR protocols that reliably discriminate B virus from HSV should permit the direct detection of B virus infection without needing to resort to the more hazardous procedure of culturing virus. PCR has the additional advantage of being more rapid, potentially providing results in a matter of hours rather than days. A quantitative real-time PCR method has been developed by the National B virus Resource Center and is being evaluated for use as a clinical diagnostic. While a PCR diagnostic would substantially reduce the risk to laboratory workers, the samples tested could contain viable B virus and need to be handled with appropriate caution.

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