Pathological Features and Genomic Characterization of an subsp. Bearing Unique Virulence-Associated Genes from an Adult Horse with Pleuropneumonia.

subsp. is the etiological agent of sleepy foal disease, an acute form of fatal septicemia in newborn foals. is commonly found in the mucous membranes of healthy horses' respiratory and alimentary tracts and rarely causes disease in adult horses. In this study, we report a case of a 22-year-old American Paint gelding presenting clinical signs associated with an atypical pattern of pleuropneumonia subjected to necropsy. The gross and histopathological examinations revealed a unilateral fibrinosuppurative and hemorrhagic pleuropneumonia with an infrequent parenchymal distribution and heavy isolation of . The whole genome sequence analysis indicated that the isolate shared 95.9% homology with the only other complete genome of subsp. available in GenBank. Seven virulence-associated genes specific to the isolate were identified and categorized as iron acquisition proteins, lipopolysaccharides (LPS), and capsule polysaccharides. Moreover, four genes (, , , and ) shared higher amino acid similarity with the invasive spp. than the reference subsp. genome. Availability of the whole genome sequence will allow a better characterization of virulence determinants of subsp. , which remain largely elusive.