Early mortality in mice reflects differential virulence of Mycobacterium bovis and Mycobacterium tuberculosis in C3H/HeJ mice: A pilot study.

Understanding host-pathogen interactions between Mycobacterium bovis and Mycobacterium tuberculosis is critical for elucidating pathogen-specific infection dynamics. This pilot study was designed to compare the progression of infection in mice following inoculation with M. bovis or M. tuberculosis via intratracheal or oral gavage routes. We utilized the C3H/HeJ strain, a susceptible mouse model that exhibits severe pulmonary inflammation and poor bacterial control, a valuable tool for studying the spectrum of tuberculosis infection. Direct pulmonary inoculation of M. bovis was associated with earlier mortality, stronger inflammation, severe pathology, and earlier dissemination than pulmonary M. tuberculosis, whereas oral-gastrointestinal exposure to M. bovis produced a distinct systemic IL-1β-associated response without overt signs of disease. This work establishes the feasibility of using these infection modalities to guide investigations into pathogen-specific host-pathogen interactions.