Fig. 6. HphR is essential for virulence, while HphA and HsmA are accessory factors enhancing infection.

a Survival of mice following intraperitoneal injection with ~2 × 10⁶ colony-forming units (CFU) of AB5075 (WT), or transposon mutants. Statistical significance determined by log-rank (Mantel-Cox) test. ns P ≥ 0.05, *P < 0.05. WT vs. hphA112::Tn26 P = 0.1211 and WT vs. hphR109::Tn26 P = 0.0191. b–d Clinical scores of each mouse group after intraperitoneal infection with WT (b), hphA112::Tn26 (c), or hphR109::Tn26 (d). Dotted line indicates threshold for euthanasia. e–g Groups of 5 BALB/c mice were infected with ~5 × 10⁷ CFU of AB5075 (WT) or transposon mutants via intranasal inoculation. Bacterial burdens in the lung (e), spleen (f), and blood (g) were determined by quantitative bacteriology at 24 h after inoculation. The data are presented as mean ± standard deviation (n = 5) and represent one of two experiments with similar results. The detection limit (dotted lines) for bacterial burdens was 1.3 log₁₀ CFU/organ for the lung and spleen and 2.0 log₁₀ CFU/ml for blood. Differences in the bacterial burdens were assessed by one-way ANOVA followed by Dunnett’s post hoc multiple comparisons test *P < 0.05, ***P < 0.001, or ****P < 0.0001 vs. WT. Adjusted P values correspond to each of the following groups vs. WT: hemTR::Tn26 P = 0.0207 (e), P = 0.0130 (f), P = 0.0217 (g); hphR109::Tn26 P < 0.0001 (e), P < 0.0001 (f), P < 0.0001 (g); hphA112::Tn26 P = 0.1639 (e), P = 0.0561 (f), P = 0.0224 (g); hsmA150::Tn26 P = 0.0007 (e), P < 0.0001 (f), P < 0.0001 (g).