Fig. 1

a The effect of E. piscicida infection on the expression of CD44a variants in zebrafish larvae. b, c The antibacterial effects of zebrafish CD44a variants at 6 and 24 hpi. d Larval survival analysis in the WT zebrafish microinfected with FLAG, CD44a_tv1-FLAG or CD44a_tv2-FLAG (n = 60 for each group). e Cartoon showing the position of the target site and its sequence in the zebrafish CD44a locus. f Representative Sanger sequencing results of the PCR amplicons from homozygous mutations with 14 bp deletions (CD44a^−/−-14del), 10 bp insertions (CD44a^−/−-10IS) or WT. g The expression of CD44a variants in the WT and CD44a^−/−-14del zebrafish larvae. h Zebrafish larvae from the WT and CD44a^−/−-14del mutants were collected at the indicated post-infection time points, and homogenates were made for CFU counts. i Zebrafish larvae from the WT and CD44a^−/−-10IS mutants were collected at the indicated post-infection time points, and homogenates were made for CFU counts. j Larval survival analysis in the WT and CD44a^−/−-14del zebrafish larvae infected with E. piscicida (n = 120 for each group). k Larval survival analysis in the WT and CD44a^−/−-10IS zebrafish larvae infected with E. piscicida (n = 120 for each group). For b, c, h and i, each symbol represents the average counts of ten larvae. For a–c and g–i, the data are presented as means ± SD (n = 3). **p < 0.01.