Characterization of a Canadian mink H3N2 influenza A virus isolate genetically related to triple reassortant swine influenza virus

Abstract

In 2007, an H3N2 influenza A virus was isolated from Canadian mink. This virus was found to be phylogenetically related to a triple reassortant influenza virus which emerged in Canadian swine in 2005, but it is antigenically distinct. The transmission of the virus from swine to mink seems to have occurred following the feeding of animals with a ration composed of uncooked meat by-products of swine obtained from slaughterhouse facilities. Serological analyses suggest that the mink influenza virus does not circulate in the swine population. Presently, the prevalence of influenza virus in Canadian farmed and wild mink populations is unknown. The natural occurrence of influenza virus infection in mink with the presence of clinical signs is a rare event that deserves to be reported.

FIG. 1.

Phylogenetic tree of the HA gene nucleotide sequences of recent H3N2 triple reassortant Canadian influenza virus isolates. The GenBank accession number of each strain is indicated on the right, next to the name of the strain. The strains have been classified in four distinct clusters (I to IV), as previously described (17). Bootstrap values are indicated, except for cluster IV, where some are omitted for clarity. The horizontal scale bar indicates the distances between strains; a 0.1 distance means that the strains possess 90% nucleotide identity.

FIG. 2.

HI antibody titers of swine sera for a 2005 H3N2 Canadian SIV isolate and mink influenza virus. The HI antibody titers of swine sera for the Quebec SIV reference strain (Sw/Qc/4001/05) were compared to the HI antibody titers for the mink influenza virus isolate (Mk/NS/1055488/07). (A) The mean HI antibody titers of the sera that tested positive are represented along with the standard errors of the means. (B) The absolute HI antibody titers of each serum sample for both viruses are illustrated.