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Fig. 5 Heat-killed E. coli lysate does not enhance V. cholerae pathogenicity in the absence of T6SS-mediated killing. (A) Survival curves of larvae coinfected with a 1:1 mixture of E. coli (Ec) or heat-killed E. coli lysate (HK Ec) with WT V. cholerae (Vc WT) or ΔT6SS V. cholerae (Vc ΔT6) (~1500 CFU each). Data are pooled from three independent experiments, each with 11–20 larvae. Significance was assessed by log-rank Mantel-Cox test. (B) Enumeration of recovered V. cholerae or E. coli at 0, 6, or 24 hpi from zebrafish larvae coinfected with a 1:1 mixture of E. coli (Ec) or heat-killed E. coli lysate (HK Ec) with WT V. cholerae (Vc WT) or ΔT6SS V. cholerae (Vc ΔT6) (~1500 CFU each). Circles represent individual larvae. Data were pooled from three independent experiments, each with 3–5 larvae per time point. Significance was assessed by unpaired t-test on Log10 transformed values. (C) Fold change in the expression of cxcl8a, tnfa, il1b, mmp9 and cxcl18b in larvae coinfected with 1:1 mixture of E. coli (Ec) or heat-killed E. coli lysate (HK Ec) with WT V. cholerae (Vc WT) or ΔT6SS V. cholerae (Vc ΔT6) (~1500 CFU each) relative to mock infected larvae at 6 hpi or 18 hpi. Data were pooled from three independent experiments, each with 10–15 larvae per time point. Significance was assessed by one-way ANOVA with Tukey’s multiple comparisons test on Log2 transformed values. For all panels, bars indicate mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001, ****p<0.0001, and ns (not significant). https://doi.org/10.1371/journal.ppat.1012384.g005