Reduced effectiveness of Abeta1-42 immunization in APP transgenic mice with significant amyloid deposition

Vaccinations with Abeta1-42 have been shown to reduce amyloid burden, and improve cognition in transgenic models of Alzheimer's disease (AD).The goal of this study was to test the efficacy of Abeta1–42 immunization in Tg2576 (model of AD) mice with varying degrees of amyloid burden at the time of immunization. Results demonstrate that Abeta1–42 immunization of Tg2576 mice was effective in reducing amyloid burden in young mice but did, not significantly alter beta- amyloid burden in older Tg2576 mice. Furthermore, in contrast with reports on the PDAPP mice, immunization of Tg2576 mice with Abeta1–42 appeared to be more effective in reducing Abeta 42 than Abeta 40. This selectivity is most apparent in the older Tg2576 mice with heavy amyloid loads, where Abeta1–42 immunization only reduced Abeta 42 levels without altering Abeta 40 levels or beta amyloid plaque load.