Expression of genes associated with the antigen presentation and processing pathway are consistently regulated in early Mycobacterium avium subsp. paratuberculosis infection.

The primary objective of this study was to evaluate early gene expression profiles associated with paratuberculosis in cattle exposed to known infectious doses of Mycobacterium avium sub-species paratuberculosis (MAP). A Johne's disease experimental infection field trial was conducted on a mixed population of Holstein and Holstein Red cattle. Blood samples from four MAP exposed and four unexposed cattle, selected based on IFNγ expressions were taken at 9, 13 and 21 weeks and RNA processed to Affymetrix GeneChip™ Bovine Genome arrays. Ontological analysis revealed consistent differences in gene expression between MAP exposed and control animals. A stark variation was observed in expression of a number of genes along antigen presentation pathways, suggesting that MAP exposure potentially results in the host immune response switching to a CD8(+) biased antigen presentation profile. This requires further in-depth analysis since it exposes a hitherto unconfirmed association between MAP exposure and in vivo MHC gene modulation.