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?) plays a vital role in the immune response to TB and recent studies provide insights into the interactions between M? and Mycobacterium bovis. Here we reveal the early transcriptional response of bovine AlvM? to M. bovis infection. We demonstrate up-regulation of immune response genes, including chemokines, members of the NF-?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? 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? seems to differentiate between the two stimuli.