Y-5A15 immunization decreased cerebral amyloid-β (Aβ) peptide levels in the brains of APP/PS1 transgenic mice. (a) Representative microscopic images of brain sections from different groups. Sections were stained with the anti-human Aβ antibody 4G8 (Green) and thioflavin S (ThS), counterstained with DAPI (blue) to detect nuclei. The number of 4G8-positive (b) and ThS-positive plaques (c) were quantified in the hippocampus (Hip) and cortex (Ctx) by IpWin5 software. (d) ELISA analyses of insoluble human Aβ40 and Aβ42 in the brains. (e) ELISA analyses of soluble human Aβ40 and Aβ42 in the brains. Compared with AD control, * p < 0.05, ** p < 0.01, Student’s t-test, n = 6 mice per group. Scale bar is 200 μm.