Hemagglutination Inhibition (HAI) Assay

Serological detection of total antibodies (IgM and IgG) directed towards Japanese Encephalitis (JE) virus by Hemagglutination Inhibition (HAI) assay.

Serum. Minimum volume of 400 mL required. Cerebrospinal fluid (CSF) can be submitted (200 mL) 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-JE antibodies are present in the patient’s serum (via HAI testing).

Collect blood in serum separator tubes.

Store samples refrigerated until time of shipment.

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 Japanese Encephalitis virus and has travel to endemic area.

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 Japanese Encephalitis virus. Results are expressed as the reciprocal of antibody titre.

Due to the cross-reactive nature of flavivirus antibody, (Eg. Yellow Fever, Dengue, Powassan, etc.) the detection of total JE specific antibody in a single sera is indicative of past or present exposure to this agent, or a related agent from the same virus genus. A 4 fold rise or greater in neutralizing antibody titre, is required to document a "confirmed case" of infection with associated illness.

Isolation of an arbovirus, or detection of arboviral antigen or nucleic acid in a clinical specimen would constitute firm evidence of viral association with illness and provide "confirmed case" status.

14 Calendar days.

1. 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.