A serological survey of influenza D virus infection in cattle in Hokkaido, Japan

Abstract

Influenza D virus (IDV) is an emerging pathogen associated with bovine respiratory disease complex. To update the epidemiological status of IDV in Hokkaido, Japan, we tested 73 serum samples collected in 2023 from cattle with respiratory disease or diarrhea. Hemagglutination inhibition (HI) assays were performed using three IDV strains representing distinct phylogenetic clades: D/swine/Oklahoma/1334/2011, D/bovine/Yamagata/10710/2016 (Y16), and D/bovine/Yamagata/1/2019 (Y19). Overall, 34 of the 73 samples (46.6%) were seropositive. Antibodies against Y16 were detected most frequently (42.5%), whereas the highest mean HI titers were observed against Y19 among the three strains. These results indicate that IDVs belonging to both the Y16- and Y19-lineages are circulating among cattle in Hokkaido, consistent with previous epidemiological findings.