Mycobacterium avium subspecies paraturberculosis (MAP) is the causative agent of Johne’s disease, an enteritis infection that affects ruminants1.This disease has been studied in deer, but there is little information regarding immunity or disease related immunopathology2. There is evidence that host genetics contribute to resilience or susceptibility to Johne’s disease 3. The purpose of this study was to identify genes in both the innate and adaptive immune system as biomarkers for the resilient (R) or susceptible (S) phenotype in red deer.
Over 3 years, we have had bred over 60 animals from sires with a confirmed R or S phenotype. Animals were bled routinely and blood monocyte derived macrophages (MDMs) or whole PBMCs were obtained by in vitro cultures. Cells were stimulated and RNA was used for qPCR reactions. The 15 most informative gene targets were chosen from a panel of 60 using GenEx software.
Analysis of stimulated MDMs shows markedly higher level of expression of immune genes such as IL1A, TNFA, IL23A and IL12A in susceptible animals. We have also identified genes not involved typically associated with the immune system, such as PKLR that exhibit this pattern. Conversely, PBMC samples from these animals exhibit higher levels of gene expression of immune genes such as IFNY, IL17A and IL2 in resilient animals. These results have been reproduced in animals bred from different sires over several years.
We intend to incorporate these gene markers into diagnostic tests to identify R and S animals at an early age. These genes may also provide deeper insights into immune parameters that determine disease outcome in an animal.