Early response of bovine alveolar macrophages to infection with live and heat-killed Mycobacterium bovis

Bovine tuberculosis (TB) is a disease of economic importance and a significant animal health and welfare issue. The alveolar macrophage (AlvM[phi]) plays a vital role in the immune response to TB and recent studies provide insights into the interactions between M[phi] and Mycobacterium bovis. Here we reveal the early transcriptional response of bovine AlvM[phi] to M. bovis infection. We demonstrate up-regulation of immune response genes, including chemokines, members of the NF-[kappa]B pathway which may be involved in their transcription and also pro- and anti-apoptotic genes. M. bovis may therefore induce multiple mechanisms to manipulate the host immune response. We compared the response of AlvM[phi] to infection with live and heat-killed M. bovis to determine transcriptional differences dependent on the viable pathogen. Several chemokines up-regulated following live M. bovis infection were not up-regulated after heat-killed M. bovis stimulation; hence the M[phi] seems to differentiate between the two stimuli.