IL18 and infection: In contrast, LVS‐infected macrophages showed a three‐ to four‐fold increase in TNF‐a and IL‐18 expression levels compared to uninfected controls at almost every time point (except 18 HPI for IL‐18), suggesting that macrophages are in a state of immune activation even after replication has been controlled, or that LVS infection may activate macrophages earlier than less attenuated strains.