Diarrhea is a common disease in sika deer. The causes of diarrhea in sika deer are complex and involve a variety of pathogens. Additionally, new virulent pathogens are continuously emerging, which poses a serious threat to deer’s health and particularly affects fawns’ survival rate. In the present study, feces samples were collected from fawns with diarrhea in Jilin Province, in the northeast of China. The viral communities were investigated using the metagenomic method. Viral metagenome data revealed that the viruses in the fecal samples were mainly from 21 families in 14 orders. The major viruses in high abundance were astrovirus, rotavirus, coronavirus, and bovine viral diarrhea virus. In addition, a large number of phages, which mainly belonged to the family Siphoviridae, were identified. Then, the known causative virus species were investigated via RT-qPCR. The results showed that the infection rates of bovine coronavirus, bovine rotavirus, and bovine viral diarrhea virus were 59.44%, 58.89%, and 21.67%, respectively, and mixed infections were commonly seen in the samples. A bovine rotavirus strain was successfully isolated from the positive samples. Whole-genome sequencing revealed that the genotype of the strain was G6-P[1]-I2-R2-C2-M2-A3-N2-T6-E2-H3, indicating the recombination of rotavirus. This study revealed the profiles and characteristics of viruses that cause sika deer diarrhea, which will be helpful for understanding diarrhea diseases in sika deer.

L. monocytogenes is a common foodborne pathogen that typically causes infections through the consumption of food contaminated with this bacterium. This study seeks to elucidate the biodiversity as well as evolutionary characteristics of L. innocua strains from different regions using comparative genomics, exploring the virulence and pathogenic potential of these strains. The findings are expected to deepen our understanding of L. innocua and provide valuable reference for public health risk assessment related to this bacterium. We performed comparative genomics on 108 food-source L. innocua isolates sourced from the USA, England, China, and Egypt to explore their biological traits and assess their pathogenic potential by predicting virulence and antibiotic resistance genes, with subsequent validation of pathogenicity through animal studies. Pan-genomic analysis showed that geographically distinct L. innocua strains possess open genomes, offering a stable genetic basis that facilitates adaptation to diverse environments. Through virulence gene prediction, we found that L. innocua strains from different regions harbor virulence genes identical to those found in pathogenic L. monocytogenes, such as inlA and inlB, as well as internal genes that may enhance the pathogenic potential of the strains. This finding demonstrates that L. innocua strains exhibit pathogenic potential. To validate their virulence, we subsequently conducted virulence assays utilizing the Galleria mellonella larval model. Following infection with L. innocua, 100% mortality was observed in a subset of Galleria mellonella larvae, albeit with a delayed time to death compared to L. monocytogenes infection. This indicates that while L. innocua exhibits attenuated virulence relative to L. monocytogenes, it retains pathogenicity. Consequently, the potential contribution of L. innocua to listeriosis cannot be overlooked in public health risk assessments. L. innocua strains isolated from food can carry virulence and resistance genes identical to those found in pathogenic L. monocytogenes strains, indicating that these L. innocua strains possess certain virulence and pathogenic potential, which was further validated through subsequent animal experimentation. This study enhances our genomic understanding of L. innocua and underscores that detecting its key virulence genes is critical for public health safety, thereby providing valuable insights into its pathogenic potential.