(A) The per capita effect of wild-type Aeromonas, ΔAimA, ΔAimB, and ΔAΔB. Each dot represents the average neutrophil response from a flask of 15 fish divided by the average colonization level from a flask of 15 fish, normalized to 104. (B) Survival curve of zebrafish mono-associated with wild-type A. veronii (N = 163), ΔAimA (N = 139), ΔAimB (N = 174), ΔAΔB (N = 148), and ΔAΔB + AimA (N = 60). *indicates significant difference from the survival curve with wild-type Aeromonas, Mantel-Cox test. (C) myd88-/- transgenic fish lack a neutrophil response to bacteria. Each dot represents one fish. (D) ΔAΔB colonization is rescued to wild-type colonization levels in myd88-/- transgenic fish. Further, both wild-type Aeromonas and ΔAΔB reach significantly higher colonization levels in the myd88-/- transgenic fish compared to wild-type fish, indicating that the innate immune response limits commensal bacterial growth. (E) Survival curves of myd88-/- zebrafish over a 3 day infection. GF myd88-/- (N = 45), CV myd88-/- (N = 120), Aer myd88-/- (N = 100), ΔAΔB myd88-/- (N = 124). (F) Survival curve of conventionally raised (CV) fish treated with LPS (N = 163), with LPS and AimA (N = 163), with LPS and AimB (N = 121), or with LPS and mLCN (N = 69). Letters next to key indicate significant difference between the survival curves, Mantel-Cox test. For all graphs, letters indicate significance by ANOVA with multiple comparisons.