PCV-2 vaccination modifies the cytokine serum profile in wild boar (Sus scrofa) coinfected with tuberculosis and PCV-2

Animal tuberculosis (TB) and porcine circovirus 2 (PCV-2) coinfections have been associated to the development of severe patterns of tuberculous lesions. These coinfections are frequently observed in wild boar, considered the main wild reservoir of TB in Spain. The vaccination of wild boar with a single dose of PCV-2 vaccine has been associated with less severity of lesions. However, the underlying immune mechanisms affecting these animals remain scarcely known. The aim of this study was to determine whether PCV-2 vaccination alters cytokine concentrations in the serum of wild boars naturally coinfected with TB and PCV-2. Serum samples were collected from hunted wild boar in game estates where part of the population had been previously vaccinated against PCV-2. Serum cytokine concentrations were measured using the MILLIPLEX MAP multiplex assay, and the results were analysed using Principal Component Analysis (PCA). The results suggest significant differences in the concentrations of IL-1β, IL-2, IL-10, IL-12, and IL-18 cytokines between PCV-2-vaccinated and non-vaccinated animals, with lower levels observed in the vaccinated group. IL-1β, IL-2, IL-12 and IL-18 are pro-inflammatory cytokines involved in Th1 response. Exacerbated inflammatory responses can result in more severe lesional patterns. Therefore, the reduced levels of these cytokines observed in PCV-2-vaccinated animals could be associated with the presence of less severe tuberculous lesional patterns.