Cytokine production was assayed from the collected sera of infected mice using a multiplex cytokine assay kit and Luminex technology (Bio-Rad). Balb/C mice were infected with Lm (10 3 ), the wild type L.inn (10 7 ), or the L.inn::vgc (10 7 ) strain. Sera were aseptically isolated on days 1, 2, 3, and 4 post-infection. Four cytokines were tested: TNFa, IL-1b, IL-6, and IL-12(p70) and cytokine levels were presented as absolute concentrations in pg/ ml.