Expression of immunoregulatory genes in peripheral blood mononuclear cells of European wild boar immunized with BCG

The objective of this study was to analyze the expression of immunoregulatory genes in European wild boar (Sus scrofa) immunized with BCG. Eighteen immunoregulatory genes were selected for expression analysis based on their role in host immune response during tuberculosis and/or for their association with resistance to bovine tuberculosis in European wild boar populations. Initially, mRNA levels were analyzed by quantitative real-time reverse transcription PCR (qRT-PCR) in spleen samples from Mycobacterium bovis-infected (N = 18) and uninfected (N = 22) European wild boar. Statistical analysis of qRT-PCR data revealed that four genes, complement component C3, IFN-gamma, IL-4 and RANTES were downregulated in infected animals (P < 0.05). These genes were selected for analysis of mRNA levels in peripheral blood mononuclear cells (PBMCs) from seven wild boar experimentally immunized with BCG and seven non-immunized controls. Blood was collected at 0, 5, 13 and 25 weeks post-immunization (wpi). The mRNA levels of IFN-gamma and C3 showed a peak (>15-fold increase) at 5 wpi, whereas transcripts for RANTES and IL-4 showed a peak (>2-fold increase) at 13 wpi in BCG-immunized animals when compared to non-immunized controls. The pattern of expression of these genes over the time provides the first description of BCG specific immune response in European wild boar. These results provide new insights into the molecular basis of wild boar response to M. bovis infection and BCG vaccination and may be used to monitor BCG vaccination in this species.