IDE and infection: Therefore, we measured the expression of three Aβ-degrading enzymes in the brain, namely insulin-degrading enzyme (IDE), neprilysin (NEP), and matrix metalloproteinase 9 (MMP9), using RT-PCR, and we observed a significant increase in the expression of MMP9 and IDE mRNA following infection with T. gondii (MMP9: 1.3 ± 0.1 fold-change over 5xFAD controls, p < 0.01, Fig. 6b’; IDE: 1.7 ± 0.1 fold-change over 5xFAD controls, p < 0.01, Fig. 6b”).