Unexpectedly, and in contrast to the results from the HD11 infections, neither obvious NO production nor differential expression of the immune cytokines, such as IL1β, IL6, IL8, IFN-γ, and IL18 was detected in infected cattle macrophages Bomac (regardless of the infecting serovars) compared to uninfected cells under the same tested conditions, indicating a big difference in the immune response between the chicken and bovine macrophages to Salmonella infections. The gene discussed is IL18; the disease is infection.