Identification of Hunnivirus in Bovine and Caprine Samples in North America

Diarrhea in young ruminants is a global issue and causes significant economic losses worldwide. In addition to common pathogens like rotavirus, coronavirus, and astrovirus, new viruses can be identified through unbiased next-generation sequencing (NGS) techniques. Here, we report the initial identification of a hunnivirus from a one-month-old goat with diarrhea using shotgun metagenomic NGS. A complete hunnivirus genome was recovered. Phylogenetic tree analysis revealed that this goat hunnivirus was more closely related to cattle hunnivirus than to small ruminant hunnivirus strains, suggesting a prior cross-species transmission event. The genome was used to design primers/probes for the conserved 3D^pol RdRP gene for real-time RT-PCR to screen banked ruminant fecal samples. Screening of 144 ruminant fecal samples showed that 9 of 38 goat, 22 of 98 cattle, and 0 of 8 sheep samples were positive for hunnivirus. Sequencing of the 3D^po region was performed on selected positive samples and revealed two lineages of hunnivirus circulating in North America. Our study highlights the importance of further investigation and monitoring of fecal samples using unbiased metagenomic tools to identify potential pathogens or co-infections in ruminants.