In summary, our results show that administration of the lytic mycobacteriophage D29: (i) is an effective approach for reducing M. ulcerans-induced pathology in the mouse model of infection; (ii) reduced M. ulcerans numbers in the footpad and the DLN, associated with increased IFN-γ and TNF levels and; (iii) is not associated with detectable side effects over a minimum delay of 150 day observation period. This evidence concerns the gene IFNG and infection.