FIG. 4.

Sensing of Salmonella PrgJ is independent of NAIP5. (A) Flow cytometry of wild-type (WT; C57BL/6), isogenic Naip5^−/−, or Nlrc4^−/− macrophages transduced with retroviruses expressing N65-GFP, GFP-C65, or Salmonella PrgJ. The PrgJ construct expressed GFP downstream of an internal ribosome entry site. (B) IL-1β release by wild-type, Naip5^−/−, or Nlrc4^−/− macrophages transfected with purified Salmonella flagellin (FliC), PrgJ, or SsaI proteins. (C) Cell death assessed by LDH released from wild-type, Naip5^−/−, or Nlrc4^−/− macrophages infected with wild-type Listeria, Listeria expressing PrgJ, or Listeria expressing Legionella FlaA. The expression of PrgJ or FlaA was induced by the addition of the indicated concentrations of IPTG. *, P < 0.001. For B and C, two-way ANOVA and Bonferroni's test were used to determine the statistical significance (P) of differences in IL-1β and LDH release. Significance tests were done versus WT macrophages or versus both Naip5^−/− and WT macrophages when transfecting with PrgJ (B) or infecting with Listeria expressing PrgJ (C). For each panel, data shown are from a single representative experiment of at least two that produced similar results.