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Hemagglutination Inhibition (HAI) assay

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Accredited by the Standards Council of Canada to Laboratory no. 594 (ISO/IEC 17025)

Requisition Forms

Reference Details


Antigenic strain characterization for Influenza virus by Hemagglutination Inhibition (HI) assay.

Test Category:
Strain Characterization
Influenza virus
Illnesses and Diseases:
  • Influenza

Viral isolate. Volume required - minimum 1.0 mL.

Collection Method:


Specimen Processing, Storage and Shipping:

Keep samples refrigerated until shipped for testing. Ship on dry ice.

Transportation of Dangerous Goods:

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.

Patient Criteria:

Suspected or confirmed influenza infection.

Accompanying Documentation:

Completed requisition (current WHO Influenza Program – Antigenic Subtyping requisition form). The sender's lab name, address, and telephone number must be included for samples to be processed. Also include identifier (sender lab number), patient date of birth, patient gender, type of specimen, and date collected. Under additional information, please include if possible/applicable: passage history, patient travel history, extent of influenza activity, and date of collection relative to antiviral use.


Samples received three months after the collection date will not be tested unless prior arrangements have been made with the Section Chief.  

Methods and Interpretation of Results:

The influenza virus hemagglutinin protein (HA) agglutinates red blood cells (RBCs). Specific attachment of antibody to the antigenic sites on the HA molecule interferes with the binding between the HA and receptors on the RBC, inhibiting hemagglutination. In the HI test, a standardized quantity of HA antigen is mixed with serially diluted antisera, and RBCs are added to determine the specific binding of antibody to the HA molecule. Submitted viral isolates are identified (subtyped) by comparing their HI titres to reference antisera with the titres of reference antigen to homologous reference antisera.

Turnaround Time:

14 calendar days. Please note that the turn-around time for viral isolates requiring more than one subculture/passage will be extended to 20 calendar days.

Phone #: (204) 789-6047
Fax: (204) 789-2082
  1. Concepts and Procedures for Laboratory-Based Influenza Surveillance, U.S. Department of Health and Human Services, Public Health Service/Centers for Disease Control July 1982.
  2. WHO Manual on Animal Influenza Diagnosis and Surveillance, World Health Organization, Department of Communicable Disease Surveillance and Response, WHO/CDS/NCS/2002.5 Rev.1.
  3. Serologic Detection of Human Influenza Virus Infections by Hemagglutination-Inhibition Assay Using Turkey RBCs, LP-003, R-1 (K. Hancock). Public Health Service, Centers for Disease Control and Prevention (CDC), Atlanta, GA. Effective October 2, 2009.