Mycobacterium avium subspecies paratuberculosis (MAP) is a facultative intracellular pathogen that resides in host macrophage cells. Presently, little is known about how MAP is able to subvert the normal bacteriocidal functions of infected macrophages. Previously, our group identified a dramatic up-regulation of interleukin-1alpha (IL-1α) and tumor necrosis factor receptor-associated protein 1 (TRAF1) gene and protein expression within ileal tissues from MAP infected dairy cattle. IL-1α is a proinflammatory cytokine secreted by macrophages and other cells. TRAF1 protein is expressed by many cell types and has been demonstrated to negatively regulate apoptosis and other cell signaling functions. High-level expression of these two proteins could therefore have profound effects on macrophage function and apoptosis. We now present immunohistochemical evidence that high levels of TRAF1 protein are located primarily within macrophage cells infiltrating areas of active MAP infection, while IL-1α displays a diffuse staining pattern, consistent with secretion from cells within these lesions. We also report on experiments where cultured bovine monocyte derived macrophage cells (MDM) were challenged with live MAP and stimulated with recombinant IL-1α. Western blot analysis identified a dose dependent increase in TRAF1 protein levels in bovine MDM in response to infection with live MAP and to treatment with recombinant IL-1α. Using IL-1α receptor antagonist to block IL-1α receptors of bovine MDM, we also demonstrate that TRAF1 protein expression in MAP infected bovine MDM is dependent upon production of IL-1α following infection. Our studies further suggest that primary bovine macrophages cells constitutively express IL-1α and that TRAF1 protein increases with time in culture. MAP apparently uses the IL-1α - TRAF1 system to enhance TRAF1 protein expression in infected bovine MDM. These novel results provide evidence for a new avenue of research on the effect of MAP and other intracellular pathogens on macrophage signaling and apoptosis.