Virulence of Mycobacterium avium Subsp. hominissuis Isolated From Feline Thyroid and Pancreatic Tissues in a Murine Infection Model.

Mycobacteria infection is a serious public health problem and has been described as causing diseases in domestic animals. The objective of this study was to evaluate the immunopathogenesis of Mycobacterium avium subspecies hominissuis isolated from a domestic cat in mice. Mice were intravenously infected with 106 CFU, and the spleen, lung, liver, and submandibular glands were collected for a histopathology study and bacillary load evaluation. Lung cells, such as macrophages, NK1.1 cells, and CD4+ and CD8+ T lymphocytes were evaluated by flow cytometry. The infection spread to the liver, lungs, lymph nodes, and submandibular salivary gland, causing severe necrotic lesions and inducing increased levels of lung macrophages, NK, and dendritic cells, as well as specific CD4+IFN-γ+ and CD8+IFN-γ+ T lymphocytes. Thus, Mycobacterium avium subsp. hominissuis presented here induced pathogenicity and immune responses in the mouse model, as other mycobacterial infections, indicating that this bacterium could induce serious disease in animals.