Objective This study was conducted to screen differential metabolites in serum of sheep infected with Echinococcus granulosus, discover serum metabolites with potential diagnostic value, and provide candidate biomarkers for non-invasive blood detection of cystic echinococcosis in sheep.
Methods Untargeted metabolomics technology based on UHPLC-Q-TOF-MS was used to detect metabolites in serum samples from Echinococcus granulosus-positive and negative sheep. Principal component analysis (PCA), orthogonal partial least-squares discriminant analysis (OPLS-DA) and univariate statistical analysis were combined to screen differential metabolites. Receiver operating characteristic (ROC) curves were adopted to assess the potential diagnostic value of these differential metabolites, and the KEGG database was used to perform enrichment analysis of metabolic pathways.
Results Thirteen differential metabolites were screened out from serum samples between the Echinococcus granulosus-positive group and the negative group. Among them, four metabolites including 1,5-diaminonaphthalene, lauroyl-L-carnitine, prilocaine and mandelonitrile yielded the area under the ROC curve (AUC) greater than 0.9, showing good potential diagnostic value. KEGG pathway analysis indicated that the differential metabolites were involved in metabolic processes related to cyanoamino acid metabolism, which suggested that Echinococcus granulosus infection might be correlated with changes of amino acid metabolism in sheep.
Conclusion Four serum differential metabolites with potential diagnostic value, namely 1,5-diaminonaphthalene, lauroyl-L-carnitine, prilocaine and mandelonitrile, were identified in this study. They can be used as candidate serum diagnostic biomarkers for ovine cystic echinococcosis and provide a basis for further large-sample validation and research on non-invasive serum detection.
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