Immunological evaluation of goats vaccinated with a commercial vaccine against Johne’s disease

Authors: Bannantine, John; Stabel, Judith; KAPUR, VIVEK - Pennsylvania State University

Submitted to: Vaccines
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2022
Publication Date: 3/26/2022
Citation: Bannantine, J.P., Stabel, J.R., Kapur, V. 2022. Immunological evaluation of goats vaccinated with a commercial vaccine against Johne’s disease. Vaccines. 10(4). Article 518. https://doi.org/10.3390/vaccines10040518.
DOI: https://doi.org/10.3390/vaccines10040518

Interpretive Summary: In a previous Johne's disease goat vaccine trial, we observed significantly less Mycobacterium avium subspecies paratuberculosis shedding and tissue burden in goats receiving a commercial vaccine compared to control, infected goats. In this study we examined the immunological response in these vaccinated goats in order to identify any correlates of protection. Overall, we found the vaccinated goat immune response very similar to the infected-not vaccinated group, but we did note differences in levels of a few immune cells from the blood as well as differences in antibody levels to certain proteins produced by the pathogen. These results, when added to our previous study, yield clues to how the goat immune response counters infection of Mycobacterium avium subspecies paratuberculosis.

Technical Abstract: Johne’s disease causes an economic burden to dairy, meat and wool industries. Therefore, vaccination of goats against Mycobacterium avium subspecies paratuberculosis (Map), which causes Johne’s disease, is beneficial for controlling the disease in infected livestock. Previously, the Johne’s Disease Integrated Program (JDIP) initiated a comprehensive, multi-institutional vaccine trial for Johne’s disease using the caprine model of infection to test the efficacy of live attenuated Map vaccine candidates. In this study, we examined both the humoral and cell-mediated immune responses from kid goats enrolled in that trial. Infected only and vaccinated-challenged animals both showed IFN-gamma stimulation and proliferation of T cell subpopulations. CD4+, CD25+ and gamma delta cells from cultured PBMCs in the vaccinated group proliferate significantly when stimulated with Map antigen. The increase of CD44+ and decrease of CD62L+ cells suggest that vaccine administration lowered the inflammation associated with Map infection. Two independent experimental approaches were used to identify differences in the antibody responses of vaccinated and infected goats. Overall, a stronger antibody response was observed in the infected goats as com-pared to vaccinated goats. By screening a phage expression library with pooled serum from infected goats, antibodies were generated against previously defined Map antigens, including MAP_1272c and MAP_1569. However, a few specific antigens differentially detected by vaccinated goats that were not detected by infected goats were also identified in the library screens. A second approach identified two additional differentially reacting proteins by dot blot analysis. The results of this immunological study, combined with the microbiological and pathological findings obtained previously, provide a more complete picture of the protective effect of goats vaccinated against Map.