FIG 9.

Pathogenicity of A. actinomycetemcomitans R isolates and S strains in a Galleria mellonella larval infection model. Upon injection of an A. actinomycetemcomitans bacterial inoculum of 10 μL, the larvae were incubated at 37°C in the dark and their melanization and viability were monitored over time. Negative control groups consisted of larvae injected with 10 μL PBS (PBS) or untreated larvae (control). (A) Representative images of different degrees of larval melanization and the respective attributed scores. (B) Larval melanization on day 1 postinjection with different A. actinomycetemcomitans R isolates and the corresponding S strains or ATCC 29522 (ATCC). Statistically significant differences were assessed with the Mann-Whitney U test between two unpaired groups and Kruskal-Wallis tests with subsequent Dunn’s or Dunnett’s multiple-comparison tests (*, P < 0.03; **, P < 0.002; ***, <0.0002; ****, <0.0001). (C) Survival rates of larvae injected with A. actinomycetemcomitans (R isolates and S strains are marked in color code). The P values for differences in melanization (B) and survival rates (C) are presented in Table S3.