Upon infection, the gene expression of IFN-β was increased nearly 3-fold in infected untreated macrophages or in macrophages pre-incubated with control IgG, as compared to uninfected controls, while the gene expression of IFN-β increased by 1.5-fold in C57BL/6 macrophages pre-treated with anti-TLR4 antibodies, denoting 50% less induction of IFN-β gene expression as compared to untreated macrophages (Figure 3A, left). This evidence concerns the gene TLR4 and infection.