Hemagglutination Inhibition (HAI) Assay
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Reference Details
Serological detection of total antibodies (IgM and IgG) directed towards Powassan (POW) virus by Hemagglutination Inhibition (HAI) assay.
- Powassan encephalitis
Serum. Minimum volume of 400 uL required. Cerebrospinal fluid (CSF) can be submitted (200 uL) in cases of central nervous system infection to demonstrate that the virus has crossed the blood-brain barrier. However CSF will only be tested once it has been shown that anti-flavivirus antibodies are present in the patient’s serum (via HAI testing).
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 infection with Powassan virus.
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.
To demonstrate seroconversion, both acute and convalescent samples must be tested in parallel.
The HAI assay is used to measure the level of antibodies in a patient’s serum that will prevent the agglutination of susceptible erythrocytes by inactivated antigens that are able to attach to the erythrocyte receptors on red blood cells. A fourfold or greater increase or decrease in titre between the acute phase and convalescent phase serum is considered to be diagnostic of infection with the virus used in the test or with an antigenically related virus (another member of the Flaviviridae family). Results are expressed as the reciprocal of antibody titre.
14 Calendar days.
- Clarke, D.H. and Casals, J. Techniques for hemagglutination and hemagglutination-inhibitiion with arthropod-borne viruses. Am. J. Trop. Med. And Hyg. 1958; 7: 561-573.