To determine whether PopB could trigger IL-1β maturation in vivo independently of any of the other known T3SS effector proteins, we intratracheally infected C57BL/6 mice with 1.1×106 cfu of WT, ΔSTY or ΔSTY/ΔPopB P. aeruginosa and determined the presence of proIL-1β in total lung extracts and mature IL-1β in BALF 4.5 h post infection. This evidence concerns the gene IL1B and infection.