CASP1 and infection: We generated a similar GTPase-deficient mutant of zebrafish Gbp4 (Gbp4KS→AA) and unexpectedly found that it was not only unable to increase the resistance of zebrafish to ST infection but rather behaved as a DN that increased susceptibility to the infection (Fig. 4a) and concomitantly inhibited caspase-1 activity (Fig. 4b) and impaired ST clearance (Supplementary Fig. 3).