Potential Biomarkers and Underlying Pathogenesis of Mycoplasma synoviae Infection: Insights from Metabolomics Analysis

<i>Mycoplasma synoviae</i> (MS) is a prominent poultry pathogen that has caused considerable economic pressure on the poultry industry. Although we have a good understanding of MS infection, research is still lacking on the pathogenicity of MS and host-MS interactions, especially the metabolic basis of MS infection. In this study, a lethal MS strain ZX313 was identified. Then, untargeted metabolomic analysis was performed on the plasma of 18 SPF chickens infected with the ZX313 strain and the low-virulence strain SD2. A total of 699 and 720 significantly differentially abundant metabolites (SDMs) were detected after ZX313 and SD2 infection, respectively, among which 95 and 116 SDMs were group-specific. Metabolic pathway enrichment analysis revealed that MS infection significantly disturbed host amino acid, nucleotide and lipid metabolism. Moreover, the differential expression of amino acid metabolism in different virulence groups may be related to the severity of the disease and the pathogenicity of MS. A total of 20 plasma metabolites were identified to exhibit a significant correlation with disease severity, with an area under the curve of 0.986. These findings demonstrate that the host's systemic metabolism undergoes significant changes following MS infection, providing valuable references for elucidating infection-related metabolic alterations and their association with disease severity.