Abstract
Johne’s disease is a chronic wasting granulomatous enteritis of ruminants caused by infection with Mycobacterium avium subsp. paratuberculosis (MAP). Previous research has largely focused on the immune-associated gene expression profiles of the peripheral blood as a measure of the complex immunological response to MAP, with less information on the immune response occurring at the site of infection; the mesenteric lymph nodes. The DRL has in previous work established breed lines of deer that naturally express paternally heritable resilient (R) or susceptible (S) phenotypes to Johne’s disease. Differential expression levels of specific immune genes have been linked to R/S phenotypes which could ultimately be used in the diagnosis of S animals, and the selective breeding of R animals.
In this present study, samples from the posterior jejunal lymph nodes of 20 red deer (Cervus elaphus) experimentally challenged with MAP were taken at 13 weeks post- infection, and at 40 weeks following slaughter. Quantitative-PCR was utilised to determine expression profiles of candidate innate and adaptive immunity-associated genes. Aside from increased IFNG in intermediate (I) and S animals at 40 weeks p.i., no significant differential expression was observed between R, I and S animals in the expression of pro-inflammatory Th1, Th17 and anti-inflammatory Th2 and Treg candidate genes at 13 and 40 weeks p.i.. While this study failed to identify biomarkers associated with R/S phenotypes, a dramatic differential expression of the candidate genes between 13 and 40 weeks was observed, which may provide insights into the role and progression of immune parameters as the diseases progresses over time.