The effect of lipids from mycobacterium bovis on bovine nnate and acquired immune responses

The host/pathogen interaction is pivotal in defining the outcome of an infection. For cattle with bovine tuberculosis this occurs between antigen presenting cells and the lipid-rich surface of \(Mycobacterium\) \(bovis\). Mycobacterial lipids have been shown to modulate immune responses, however previous work used model systems, or lipids from avirulent bacteria. This study aimed to assess the bovine immunomodulatory ability of lipids extracted from virulent \(M\). \(bovis\). \(Mycobacterium\) \(bovis\) lipids were extracted and characterised. Polar and apolar fractions from different bacterial strains were similar in their composition although quantitative differences were noted. Lipopeptide was identified in the polar fractions. Polar lipid stimulation of bovine antigen presenting cells increased IL - 10 and IL - 12 production and reduced expression of MHCII and CD1b. Further investigation of the polar lipids was performed by subfractionation but no individual lipid could be found responsible for these effects. The ability of the lipid fractions to activate bovine lymphocytes was assessed. Lipopeptide in the polar fraction was found to play a role in the generation of lymphocyte responses. Screening of highly purified individual lipid molecules led to the identification of AcPIM6 which was found to be capable of driving antigen specific proliferation of bovine NKT cells