Phylogenetic Characterization and Seroprevalence of Senecavirus A from Swine Farms in Taiwan

<i>Senecavirus</i> A (SVA) is an emerging threat to swine populations due to its potential to cause vesicular lesions, which are difficult to differentiate from other vesicular diseases of swine such as foot and mouth disease (FMD), requiring significant resources for differential diagnosis. The first Taiwanese isolate of SVA was identified in 2006, although the first clinical case was not reported until 2012. The genetic characteristics and seroprevalence of SVA in Taiwan remain unclear. This study aimed to assess the seroprevalence and genetic diversity of SVA in nursery/weaned swine and finisher swine on Taiwanese pig farms. Phylogenetic analysis of seven Taiwanese SVA isolates revealed clustering into groups I and II. The 2006 and 2012 isolates shared 95.5% and 95.7% identity, respectively, with an early USA strain (MT360258), while more recent strains collected between 2018 and 2022 exhibited 95.7-98.8% identity with a 2020 USA strain (MZ733977). Serological analysis of swine from 300 farms showed significantly higher herd-level seroprevalence in nursery/weaned swine (53%) than finisher swine (6.7%). Furthermore, comparative analysis of nine known B cell epitopes showed high sequence conservation across Taiwanese and global strains. These findings provide important baseline data on the genetic diversity and seroprevalence of SVA in Taiwan and support the development of improved surveillance strategies for this emerging swine pathogen.