Persistence of Aβ seeds in APP null mouse brain.

Misfolded Aβ proteins can form proteopathic seeds that drive initiation, progression, and spreading of amyloidosis in the brain. Jucker and colleagues report that Aβ seeds can persist in mouse brain for months in the absence of host-derived Aβ and can then regain propagative and pathogenic activity in the presence of host Aβ.