Evaluation of the Mycobacterium tuberculosis SO2 vaccine using a natural tuberculosis infection model in goats

The development of new vaccines against animal tuberculosis (TB) is a priority for improving the control and eradication of this disease, particularly in those species not subjected to compulsory eradication programmes. In this study, the protection conferred by the Mycobacterium tuberculosis SO experimental vaccine was evaluated using a natural infection model in goats. Twenty-six goats were distributed in three groups: (1) 10 goats served as a control group; (2) six goats were subcutaneously vaccinated with BCG; and (3) 10 goats were subcutaneously vaccinated with SO. Four months after vaccination, all groups were merged with goats infected with Mycobacterium bovis or Mycobacterium caprae, and tested over a 40 week period using a tuberculin intradermal test and an interferon-γ assay for mycobacterial reactivity. The severity of lesions was determined at post-mortem examination and the bacterial load in tissues were evaluated by culture. The two vaccinated groups had significantly lower lesion and bacterial culture scores than the control group (P < 0.05); at the end of the study, the SO vaccinated goats had the lowest lesion and culture scores. These results suggest that the SO vaccine provides some protection against TB infection acquired from natural exposure.This research was funded by the Ministry of Economy and Competitiveness (MINECO, projects IPT-2012-0327-090000 and AGL2012-36171). Javier Bezos is a recipient of a Torres-Quevedo contract (PTQ-12-05812), funded by the MINECO and the European Social Fund.Peer Reviewe