Influenza D virus (IDV), first identified in 2011, has been detected in various animal species globally. Despite its broad host range, cattle are considered the natural reservoir of IDV. The first detection of IDV in China was made in Shandong Province, Eastern China. Subsequent reports of IDV in Southern China, including Guangdong and Nanjing provinces, followed. Notably, no infectious IDV was isolated in these cases. Herein, we present the first isolated IDV identified in bovine samples and conduct the IDV serosurveillance in Northeast China.
A total of 650 nasal swab samples were obtained from cattle herds in the cattle and sheep markets of Changchun, Jilin Province, from August to October 2023. We conducted real-time reverse transcription PCR (RT-PCR) on the collected samples following established protocols. And 12/650 samples tested positive for IDV. Subsequently, we employed RT-PCR methods to amplify the genome sequence of the positive samples (refer to Table S1). The genomic sequences of the 3/12 IDV-positive samples were obtained.
We conducted a phylogenetic analysis of these IDV sequences utilizing maximum-likelihood analysis through MEGA-XI. Specifically, phylogenetic analysis of the hemagglutinin esterase fusion (HEF) segment was performed for representative IDVs. Supplementary to this, the phylogenetic trees for non-HEF segments of IDVs are presented in Fig. S1. The outcomes of the phylogenetic analysis revealed that the IDV sequences from this study formed a distinct cluster with previously reported sequences from China, aligning with the D/Yama 2019 lineage.