SPI1 and infection: Subsequently, to ascertain whether indeed Salmonella could modulate SIRT1 or SIRT3 expression levels, we evaluated the Sirt1 and Sirt3 mRNA and SIRT1 and SIRT3 protein expression profile within RAW 264.7 macrophages upon infection with wildtype S. Typhimurium and SPI-1 (∆invC) (InvC, protein export apparatus) or SPI-2 (∆ssaV and ∆steE) (SsaV, structural component of SPI-2 needle apparatus; SteE, SPI-2 effector protein involved in driving M2 polarization) mutants of S. Typhimurium.