319. Mycobacterium avium Subsp. Paratuberculosis Infection Suppresses Purinergic Signaling and Reshapes Immune, Oxidative, and Apoptosis Pathways in Peripheral Blood Mononuclear Cells of Goats.

Abstract Johne’s disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP), is a chronic enteric infection that leads to significant production losses and remains a major challenge to livestock health and productivity. Despite extensive research, the early molecular mechanisms underlying host immune dysregulation during MAP infection are not fully understood. Emerging evidence suggests that extracellular ATP (eATP) and purinergic receptors (PRs) play critical roles in regulating immune responses during intracellular infections; however, their involvement in MAP pathogenesis in goats has not been investigated. This study evaluated the expression of purinergic receptors and associated immune, oxidative stress, and apoptosis-related genes in peripheral blood mononuclear cells (PBMCs) from naturally infected goats. Blood samples were collected from MAP-infected and uninfected control goats (n = 9/group). MAP-positive animals were resampled after 60 days prior to culling. PBMCs were isolated, followed by total RNA extraction, cDNA synthesis, and gene expression analysis using quantitative real-time PCR. At baseline, MAP-infected goats exhibited significant downregulation (P < 0.05) of key purinergic receptor genes (P2X7, P2Y14, ADORA2A), while P2Y2 remained unchanged. Inflammatory mediators NFKB1 and IL-6 were reduced (P < 0.05), whereas TLR4 and TNFα showed no significant differences. Antioxidant genes (SOD1, CAT, GPX1) were significantly decreased (P < 0.05), indicating impaired redox defense. Apoptosis-related genes demonstrated an anti-apoptotic profile, characterized by decreased BAX and CASP3, increased BCL2, and a reduced BAX/BCL2 ratio (P < 0.05). Longitudinal analysis revealed persistent downregulation of purinergic receptors at 60 days (P < 0.05), while most inflammatory and antioxidant genes returned toward baseline levels (P > 0.05). Notably, CASP3 expression increased and BCL2 decreased at 60 days (P < 0.05), suggesting temporal modulation of apoptosis pathways. Collectively, these findings indicate that chronic MAP infection is associated with suppressed purinergic signaling, attenuated immune and antioxidant responses, and dynamic regulation of apoptosis in PBMCs. These results highlight purinergic pathways as potential targets for understanding immune dysfunction and disease progression in Johne’s disease.