Besides the lack of functional T cells, nude athymic mice show resistance to Bacillus anthracis, Listeria monocytogenes and Staphylococcus aureus infection [45,46], reduced levels of circulating TNF-α, IL-6 and IFN-γ, in response to Pseudomonas aeruginosa exotoxin [47] and present a higher activation of macrophages [48]. This evidence concerns the gene IFNG and staphylococcus aureus infection.