The quantitative analysis of the transcription of ten essential Salmonella genes revealed significantly higher levels of the SPI-1 genes hilC (highest value: 2851-fold increase at 24 hpi, MOI 1; P ≤ 0.05) and, to a lesser extent, hilA (highest value: 3-fold increased at 4 hpi, MOI 1; P ≤ 0.05) as well as invF (5-fold increased at 24 hpi, MOI 1; P ≤ 0.05) in S. Infantis than in S. Typhimurium after infection of the macrophages (Fig. 7). This evidence concerns the gene SPI1 and infection.