Effect of paratuberculosis vaccination before and after oral experimental infection with Mycobacterium avium subspecies paratuberculosis in goats.

Vaccination against paratuberculosis, before or after infection with Mycobacterium avium subsp. paratuberculosis (Map), could affect the progression of paratuberculosis, the development of lesions, the peripheral and local immune response, or the colonization of Map in tissues and its elimination through feces. An experimental study was conducted with thirty-five 1.5-month-old kids, which were separated into 6 experimental groups that include different intervention combinations (vaccinated, non-vaccinated, challenged and non-challenged) at different points and slaughtered at 120 and 330 days post-infection. The use of an inactivated vaccine against paratuberculosis could avoid clinical disease manifestation but does not prevent the tissue colonization, even when applied before Map exposure, achieving a reduction in the presence of viable bacteria in tissues and limiting the progression toward diffuse lesions. The therapeutic effect in vaccinated animals could not be confirmed. In this sense, vaccination not only modulates the immune response in terms of the production of IFN-γ and antibodies in peripheral blood and reduces tissue damage but also contributes to limiting the spread of infection through reduced bacterial shedding especially in goats vaccinated before Map infection.