a and b Downregulated (a) and upregulated (b) genes in whole animal RNA-seq profiles of malt-1; npr-1, ilc-17.1; npr-1 and nfki-1; npr-1 double mutants compared to npr-1 controls. Gene ontology (GO) terms and KEGG pathways significantly overrepresented among genes dysregulated in all three mutant conditions are shown (q-value <0.05, with a minimum log2(fold-change) of ±0.25). c and d Salt chemotaxis after conditioning by food-withdrawal in the absence or presence of NaCl. *P < 0.05, **P < 0.01, ***P < 0.001, one-way ANOVA with Tukey’s post hoc HSD, N = 6 assays. d The salt chemotaxis learning defect of ilcr-1 mutants is rescued by driving ilcr-1 expression in many neurons (rab-3 or flp-21 promoters), or specifically in ASE (flp-6 promoter). e–i PA14 big lawn assays. n ≥ 81 animals. ***P < 0.001, two-sided logrank test; precise n numbers and P values are provided in Supplementary Table 1. Mutants lacking malt-1 (e) or encoding protease-dead malt-1 (f), or defective in other IL-17 signaling components (g, h) are resistant to P. aeruginosa PA14 in big lawn assays, where animals cannot escape from the PA14 lawn. The enhanced survival of malt-1 mutants is rescued by pan-neuronal expression of malt-1 gDNA. n ≥ 81 animals. i The enhanced resistance of malt-1 mutants to PA14 requires TIR-1. Like tir-1 mutants, malt-1; tir-1 double mutants are hypersensitive to PA14 infection. j–m Lifespan. n ≥ 92 animals. **P < 0.01, ***P < 0.001, two-sided logrank test; precise n numbers and P values are provided in Supplementary Table 3. j and k The lifespan of malt-1 and ilc-17.1 mutants is increased compared to N2 controls. The malt-1 phenotype is rescued by expressing malt-1 gDNA pan-neuronally (j) and the ilc-17.1 phenotype can be rescued by expressing ilc-17.1 cDNA from its endogenous promoter (k). l The lifespan phenotypes of malt-1 and ilc-17.1 mutants are not additive. m The shortened lifespan of animals overexpressing ILC-17.1 is abolished in malt-1 mutants. See also Supplementary Fig. 7, Supplementary Tables 1–3 and Supplementary Data 3–6.