First data on Eurasian wild boar response to oral immunization with BCG and challenge with aMycobacterium bovisfield strain

• Published in: Vaccine Vol. 27; no. 48; p. 6662
• Main Authors: Ballesteros, C, Garrido, JM, Vicente, J, Romero, B, Galindo, RC, Minguijón, E, Villar, M, Martín-Hernando, MP, Sevilla, I, Juste, R, Aranaz, A, de la Fuente, J, Gortázar, C
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Limited 12-11-2009
• Subjects: Animals; Cattle; Hogs; Immunization; Lesions; Tuberculosis; Vaccines; Wildlife
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2009.08.095

The Eurasian wild boar (Sus scrofa) is considered a reservoir for bovine tuberculosis (bTB) caused byMycobacterium bovisand closely related members of theMycobacterium tuberculosiscomplex in south-central Spain. The vaccination of wildlife with BCG offers an alternative to culling and to movement restriction for the control of bTB among wildlife reservoirs. In this study, we hypothesized that oral BCG immunization of wild boar would affect the expression of immunoregulatory genes and confer protection againstM. bovis. Three groups were used to describe the infection, pathological findings and gene expression profiles in wild boar: BCG-vaccinated andM. bovis-challenged (vaccinated challenged group;N=6), non-vaccinated andM. bovis-challenged (non-vaccinated challenged group;N=4), and non-vaccinated and mock-infected (control group;N=2) animals.M. boviswas isolated from 50% (3/6) and 75% (3/4) of vaccinated challenged and non-vaccinated challenged animals, respectively. All four wild boar from the non-vaccinated challenged group developed bTB-compatible lesions 114 days after challenge. In contrast, only 50% of vaccinated challenged wild boar developed lesions. The PBMC mRNA levels of IL4, RANTES, C3, IFN-gamma and methylmalonyl-CoA mutase (MUT) were analyzed at several days post-vaccination (dpi). When vaccinated challenged animals were compared to controls, all five genes were significantly upregulated at the time ofM. bovisinfection at 186dpi but IFN-gamma levels were also upregulated at 11 and 46dpi. The C3 and MUT mRNA levels were higher at 46dpi, and 11 and 186dpi, respectively, in vaccinated protected wild boar when compared to non-vaccinated challenged animals. At the end of the experiment (300dpi), the mRNA levels of selected genes were lower in non-vaccinated challenged animals when compared to control wild boar. Exposing wild boar to a dose of 104cfu ofM. bovisby the oropharyngeal route is an adequate protocol to produce an infection model in this species. Our results suggested that oral BCG immunization of wild boar results in the upregulation of immunoregulatory genes that may be associated with protective response toM. bovisinfection in this species. More studies on vaccine efficacy, delivery, and safety will be needed to confirm if oral vaccination with BCG could be used in bTB control programs for reducingM. bovisinfection and clinical disease in wild boar.