Here, through a forward genetic screen for mutants that have constitutive pals-5p::GFP expression in the absence of infection, we identify pals-17 as a new negative regulator of IPR gene expression, acting independently of pals-22. Through targeted RNA interference (RNAi) screening of non-induced pals genes, we identify pals-20 and pals-16 as two positive regulators that act downstream of pals-17 to induce IPR gene expression. Here, CTSC is linked to infection.