Detection of Antibodies Directed Towards Powassan Virus by PRNT

Serological detection of neutralizing antibodies directed towards Powassan (POW) virus by Plaque Reduction Neutralization Test (PRNT).

Serum. Minimum volume of 250ml required.

Collect blood in serum separator tubes.

Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.

Suspected Powassan infection. Submitted samples will first be analysed by the Viral Zoonosis Diagnostic Laboratory by Powassan HAI to determine if the patient has developed anti-flavivirus antibodies. Samples that are reactive can be further analysed for the presence of neutralizing antibodies. Samples that are HAI non reactive (negative) will not be tested by PRNT. This is not a routine test. Please contact the Viral Zoonosis Diagnostic Laboratory before sending specimens.

Completed Viral Zoonoses requisition including sender laboratory name, address and telephone number. Patient name and / or identifier (specimen reference number), date of birth, test(s) requested, collection date of specimen, date of on-set of symptoms, and clinical and travel history of patient.

This is not a routine test. Please contact the Viral Zoonoses Diagnostic Laboratory before sending specimens.

Antibodies directed towards members of the JE serocomplex viruses (Dengue, Saint Louis Encephalitis, POW, etc.) can cross react significantly in some serological assays. The PRNT is a more specific assay and can be used to document the presence of serum antibodies specific for a particular flavivirus. Serum samples are incubated with virus and if viral neutralizing antibodies are present, they will bind to the Powassan virus and prevent viral infection of cultural cells, and hence a reduction in the number of plaques detected. The neutralizing titre of a sample is expressed as the reciprocal of the serum dilution at which there is a 90% reduction in the number of plaques detected. If the patient has experienced more than one flavivirus infection, cross reactive results may yield uninterpretable results with this assay despite increased specificity.

14 Calendar days after the completion of HAI testing.

1. WHO. 2007. Guidelines for plaque reduction neutralization testing of human antibodies to dengue viruses.