APP and Alzheimer disease: Likewise, a single chain antibody VHH-B9 has been isolated from an immune anti-human BACE-1 phage display VHH library and shown to effectively inhibit neuronal BACE-1 in primary neuronal cultures and reduce astrogliosis and microgliosis, Aβ burden, and cognitive deficits in an APP/Tg mouse model of AD after systemic AAV-mediated delivery [62].