The project will use combined functional and classical genomics and system biology approaches (systems genetics) to investigate host-pathogen interactions and the host immune response to mycobacterium infection. The study will gather evidence to identify those genes that are important in regulating and modulating the infection process and progression of disease. The outcomes will include: 1) increased knowledge of macrophage function, and specifically the response to mycobacterial infections: the application of this knowledge may lead to tests for earlier and more accurate pre-clinical identification of infected animals; 2) the identification of genes that regulate the response of an individual to infection: information that could be applied in selective breeding programmes through genetic tests to facilitate the identification of animals that are more or less resistant to mycobacterial infection.