The recombinant L.inn::vgc strain exhibits a lowered inflammatory response At the early stages of infection, wild type Lm is engulfed by professional phagocytes like macrophages, dendritic cells, or neutrophils. These cells produce a variety of proinflammatory cytokines which recruite or activate other inflammatory immune cells. The levels of IL-1ß, IL-6, IL-12, and TNF-alpha in mice sera were measured over the first 4 days after infection with Lm (10 3 ), L.inn (10 7 ), and the L.inn::vgc strain (10 7 ). Like L. inn, , L.inn::vgc was not able to produce significant amounts of these cytokines over the first 4 days post-infection in spite of high infection doses (10 7 ) while primary infection with Lm led to high proinflammatory cytokine production (Fig. 2) .