Genomic epidemiology, evolution, and transmission dynamics of porcine sapelovirus associated with diarrheic piglets

Porcine sapelovirus (PSV) is increasingly detected in swine enteric disease complexes, but its evolutionary dynamics and transmission patterns remain insufficiently characterized. In this study, we analyzed 327 fecal samples collected from diarrheic piglets between 2015 and 2022 and identified persistent PSV detection in northeastern China. Because PSV was detected in the context of mixed enteric viral infections in this dataset, our data do not establish PSV as an independent causative agent of diarrhea. Comparative whole-genome and evolutionary analyses of globally circulating PSV strains revealed substantial genetic diversity, with higher apparent short-term substitution-rate estimates observed in the African and Japanese datasets. In China, inter-strain genetic recombination appeared to represent an additional driver of viral diversification. Temporal evolutionary analyses indicated a dynamic and complex evolutionary landscape within China. Phylogeographic reconstruction identified multiple putative transmission nodes within the currently available genome dataset, suggesting broad geographic dissemination of PSV lineages but not definitive source-sink relationships. These findings enhance our understanding of PSV genomic epidemiology and provide useful information for molecular surveillance of PSV and other diarrhea-associated viruses in swine populations.