Protective effect of selected strains against gnotobiotic zebrafish larva infection by <i>E. ictaluri</i>.

<p><b>A</b>. Four dpf-old freshly hatched axenic zebrafish larvae were kept germ-free or incubated with selected protective bacterial strains for 2 days prior to exposure to <i>E. ictaluri</i> at 6 dpf. Mortality was monitored daily after <i>E. ictaluri</i> infection. Control non-infected larvae are shown in gray. Asterisks indicate significant difference from <i>E. ictaluri</i>-infected population (***p<0.001). <b>B</b>. Inflammation marker expression in pretreated <i>E. ictaluri</i>-infected larvae. qRT-PCR was performed on 5 individual larvae per group using primers specific to <i>il1b</i>, <i>tnfa</i> and <i>il10</i> on RNA extracted at 3 dpi ( = 9 dpf) from germ-free or <i>E. coli</i> MG6155 F′ pre-colonized zebrafish larvae exposed to <i>E. ictaluri</i> at 3 days post infection. <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1002815#s2" target="_blank">Results</a> were normalized to mean expression in germ-free animals; mean ± SEM. Asterisk indicates significant difference between <i>E. ictaluri</i>-infected and uninfected populations (**p<0.01, ***p<0.001).