Quantitative Proteome Analysis of Plasma Extracellular Vesicles Identifies Three Proteins with Potential Diagnostic Value for <i>Mycobacterium bovis</i> Infection in Cows

Bovine tuberculosis (bTB) is a zoonotic disease that affects cattle and human health. Although the tuberculin skin test (TST) is the main detection method, there is a need for simpler on-farm tests using fluid samples. This study analyzed plasma extracellular vesicles (EVs) from two cow groups (Cohort A, 15 negative, 22 positive; Cohort B, 28 negative, 40 positive) to explore bTB indicators using proteome profiling. Among the 756 proteins, 217 (Cohort A) and 233 (Cohort B) showed differences between healthy and infected cows, with 47 consistently dysregulated in both groups. These proteins were related to tuberculosis, neutrophil extracellular trap formation, and antigen processing and presentation pathways. Notably, three proteins, HSPA8, B2M, and HRG, were confirmed as bTB indicators using multiple methods, including least absolute shrinkage and selection operator (Lasso) regression selection, western blot (WB), and enzyme-linked immunosorbent assay (ELISA) validation with an independent cohort (Cohort C). This study identifies plasma EV biomarkers for bTB infection, offering insights for bTB detection.