Bovine tuberculosis (bTB), caused by Mycobacterium bovis , remains a major zoonosis impacting livestock productivity and public health. To characterize species-specific immune responses and identify transcriptional biomarkers of infection, we quantified the expression of 45 immune-related genes in peripheral blood from naturally infected cattle and Mediterranean buffalo.

Differential and multivariate analyses revealed distinct species- and state-specific transcriptional signatures. Sixteen genes were significantly modulated in cattle, with Canonical Discriminant Analysis (CDA) defining a promising diagnostic signature marked by upregulation of IFNG, CASP8, CASP1, and CD83, and downregulation of IL10, CXCR2, and MMP9. In buffaloes, 22 genes were differently expressed across the three clinical groups. The first canonical function (Can1), driven positively by IFNG and IL12B and negatively by MMP9 and TLR5, effectively separated healthy from infected and affected animals, while the second function (Can2) distinguished the affected status through marked upregulation of CXCL1 and IL6.

The species-specific immune signatures uncovered underscore the importance of developing tailored biomarker panels for improved diagnosis and surveillance of bTB in different livestock species.