Dual effects of probiotic administration prior to Mycobacterium avium subsp. paratuberculosis infection are associated with immunological and microbiota shifts.

Paratuberculosis (PTB) is a chronic granulomatous enteritis caused by Mycobacterium avium subsp. paratuberculosis (Map). Vaccination is one of the most cost-effective tools for PTB control, although alternative treatments like the probiotic Dietzia have been explored with promising results. Using a rabbit model, we investigated the association of immunological and microbiota profiles in Gut Associated Lymphoid Tissue (GALT) with the effects in protection induced by the administration of Dietzia spp., the commercial vaccine (Silirum ®) and the combination of both. The treatment with the probiotic diminished inflammation, but failed to control Map burden, suggesting a detrimental effect. Rabbits treated with the probiotic presented the highest rates of tissue lesion extension, although the immunological profile was not suggestive of an inflammatory state. Map load in both vaccinated groups was similar indicating that both treatments are equally effective in eliminating the infection, suggesting the role of vaccination in eliminating the infection prevails over the immunomodulatory effects of the probiotic. There were slight variations in the presence of some taxonomic groups depending on the treatment, highlighting the complexity of microbial interactions and the need to optimise treatment combinations in the context of each disease and animal species.