Fig. 5: IleRS is critical for in vivo infection and pathogenesis of M. abscessus and M. marinum.

A Experimental design: Empty vector strains (PLJR962_KD) and IleRS-silenced strains (IleRS_KD) were pre-treated with ATC for 3d prior to infection and maintained under ATC throughout the experiment (see Methods). In the M. abscessus model, BALB/c mice (n = 9) were intranasally inoculated with 1 × 10⁸ CFU on day 0; in the M. marinum model, BALB/c mice (n = 5) were injected into the left hind footpad with 1 × 10⁵ CFU on day 0. This figure was created using BioRender.com, with permission (https://BioRender.com/lz2lysa). B Bacterial loads of M. abscessus in the lung and blood at 0, 3 and 7d post-infection. Lungs were homogenized, serially diluted 10-fold, and plated on 7H10 agar supplemented with OADC to enumerate CFU (n = 9). Error bars represent mean ± SD. C Gross pathology and hematoxylin and eosin (H&E) staining of lung tissue at 3 and 7d post-infection with M. abscessus. D Left: Footpad pathology scores after M. marinum infection (index 0 = normal; 1 = non-inflammatory swelling; 2 = inflammatory swelling; 3 = swelling extending to hind foot; 4 = swelling extending to leg; 5 = wound burst with inflammation; see Methods). Right: Bacterial loads in footpads at 5, 10, and 15d post-infection, determined by homogenization, 10-fold serial dilution, and plating on 7H10 agar (n = 5). Error bars represent mean ± SD. E Gross pathology and H&E staining of footpad tissue at 5, 10, and 15d, showing progressive histopathological changes. Statistical significance was determined by two-way ANOVA. Differences were considered statistically significant at P < 0.05 (*), P < 0.01 (**), P < 0.001 (***), and P < 0.0001 (****). “ns” denotes no significant difference.