Interestingly, TUNEL analysis of infected macrophage population revealed that during the first 2 hrs of infection, 20% of infected wild-type macrophages were apoptotic which may hinder the optimal replication of the organism, whereas infected macrophages lacking caspase-7, -1 or a functional Naip5 did not undergo early apoptosis (Figure 5F). This evidence concerns the gene CASP7 and infection.