Abstract: Objective  To establish a mouse model for low-dose Mycobacterium tuberculosis infection, and analyse the bacterial load and histopathological changes in the mouse tissues. Methods  Forty C57BL/6J mice were infected intravenously with approximately 100 colony forming units (CFU) of M. tuberculosis H37Rv. Groups of five mice were euthanatized at 1, 3, 5, 8, 12, 16, 20 and 24 weeks after infection. The lungs and spleens were homogenized and plated to determine the bacterial load. Lungs, spleens and livers were fixed in buffered formalin and embedded in paraffin, and sections were prepared with haematoxylin and eosin to observe histopathological changes.  Results  Bacterial loads in spleens reached high level (4.97±0.19) lg CFU at 3 weeks after infection, then dropped to (3.64±0.22) lg CFU at 5 weeks after infection, and were minimized to (2.75±0.23) lg CFU at 8 weeks after infection. Pathological changes in the lungs, spleens and livers occurred at 3 weeks after infection, and aggravated at 5 weeks after infection, and were lessened naturally at 8 weeks after infection.  Conclusion  A  mouse model infected with low-dose Mycobacterium tuberculosis was established successfully, and it might provide a base for the study of slow and persistence or latent M. tuberculosis infection.

Key words: Mycobacterium tuberculosis, Tuberculosis, Disease models, animal