In vivo base editing extends lifespan of a humanized mouse model of prion disease.

Prion disease is a fatal neurodegenerative disease caused by the misfolding of prion protein (PrP) encoded by the PRNP gene. While there is currently no cure for the disease, depleting PrP in the brain is an established strategy to prevent or stall templated misfolding of PrP. Here we developed in vivo cytosine and adenine base strategies delivered by adeno-associated viruses to permanently modify the PRNP locus to achieve PrP knockdown in the mouse brain.

PrP turnover in vivo and the time to effect of prion disease therapeutics.

PrP lowering is effective against prion disease in animal models and is being tested clinically. Therapies in the current pipeline lower PrP production, leaving pre-existing PrP to be cleared according to its own half-life. We hypothesized that PrP's half-life may be a rate-limiting factor for the time to effect of PrP-lowering drugs, and one reason why late treatment of prion-infected mice is not as effective as early treatment.