Prevalence of influenza A virus (H1N1) antibodies in bovine sera.

An H1 subtype-specific indirect ELISA was used to determine the prevalence of influenza A virus antibodies in a retrospective study of 2,345 bovine sera in Minnesota. Twenty-seven percent of the samples tested were positive, 31% were low-positive and 42% were negative. The prevalence of antibody appeared to peak during the months of September to November and then again from February to March. A subset of the above samples was examined by hemagglutination-inhibition (HI) to confirm the ELISA results. A 92% correlation was found between the ELISA and hemagglutination-inhibition assay. Western blot analysis on a subset of ELISA positive sera (n = 50) confirmed the presence of antibodies to the nucleoprotein and H1 hemagglutinin protein of influenza A virus.