Red-eared slider turtle-Mycobacterium marinum infection model

Mycobacterium marinum serves as an ideal model organism for studying tuberculosis due to its genetic similarity to Mycobacterium tuberculosis. However, there is a need for more suitable animal models to study M. marinum infections. In this study, we established a novel infection model using red-eared slider turtles (Trachemys scripta elegans). The turtles were infected with M. marinum via subcutaneous injection in the hind limb. Inoculation with >10⁶ CFU of M. marinum resulted in acute infection, causing mortality in at least 80% of turtles within five weeks, whereas 10⁵ CFU caused only 10% mortality. In subacute infections, M. marinum colonized and proliferated in various tissues for at least four weeks, with higher bacterial loads observed in the spleen and liver compared to the heart and lungs. Granuloma formation in the liver was correlated positively with bacterial load. Knockdown of adenylate kinase (ADK) in M. marinum reduced bacterial load by one order of magnitude in the liver and by half in the spleen, suggesting ADK as a potential drug target. Treatment with amikacin and moxifloxacin reduced bacterial load by approximately one order of magnitude in the liver and by half in the spleen. The red-eared slider turtle-M. marinum infection model developed in this study provides a robust tool for tuberculosis research.