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Updated: Oct 23, 2025
Quantitative Analyses of all Influenza Type A Viral Hemagglutinins and Neuraminidases using Universal Antibodies in Simple Slot Blot Assays
Published on: April 4, 2011
ANTIBODIES AGAINST INFLUENZA VIRUS TYPES A AND B IN CANADIAN SEALS
Lena N Measures1, Ron A M Fouchier2
1Fisheries and Oceans Canada, Maurice Lamontagne Institute, 850 route de la mer, Mont-Joli, Quebec, Canada G5H 3K6.
Abstract:
Influenza viruses have been reported from marine mammals worldwide, particularly in pinnipeds, and have caused mass mortalities of seals in North America and Europe. Because influenza viruses in marine mammals can be zoonotic, our objective was to examine Canadian phocids for exposure to influenza A and B viruses in order to understand health risks to wild populations as well as to humans who consume or handle these animals. Blood was collected from 394 seals in eastern Canada from 1994 to 2005. Sera were screened for exposure to influenza viruses in three resident species of seals: harbour, Phoca vitulina (n=66); grey, Halichoerus grypus (n=82); ringed, Phoca hispida (n=2); and two migrant species: harp, Pagophilus groenlandica (n=206) and hooded, Cystophora cristata (n=38). Included were samples from captive grey (n=1) and harbour seals (n=8) at two aquaria. Sera were prescreened using indirect enzyme-linked immunosorbent assay (ELISA), and antibodies against influenza A virus were confirmed using a commercial competitive ELISA (IDEXX Europe B.V.). A subset of influenza A virus positive sera was used to determine common virus subtypes recognized by sera using reference strains. All positive sera in the indirect ELISA reacted with influenza A virus subtypes H3, H4, and H10 using a hemagglutination inhibition assay. Sera from harbour, grey, harp, and hooded seals had antibodies against influenza A and influenza B viruses (some cross-reactivity occurred). Overall, 33% (128/385) of wild seals were seropositive to influenza viruses, with the highest seroprevalence in harp (42%) followed by harbour (33%), grey (23%), and hooded (11%) seals. Antibodies were detected in both sexes and most age classes of wild seals. Two of eight captive harbour seals were seropositive to influenza B virus and four had cross-reactions to influenza A and B viruses. This study reports antibodies against influenza A and B viruses in four seal species from the same geographic area in eastern Canada.
