Developed compact adenine base editors (SaABE8e, SaKKH-ABE8e, Nme2ABE8e, CjABE8e, SauriABE8e) that fit in single AAV vectors and outperform dual-AAV split-intein systems. Single-AAV delivery achieved 2.5-fold higher editing efficiency than dual-AAV at matched doses, with 66% liver, 33% heart, and 22% muscle editing. Demonstrated therapeutic efficacy with 93% knockdown of PCSK9/Pcsk9/Angptl3 and substantial reductions in plasma cholesterol and triglycerides. Three size-minimized ABE8e variants collectively enable targeting of ~82% of genomic adenines.
Efficient in vivo base editing via single adeno-associated viruses with size-optimized genomes encoding compact adenine base editors
Base editor delivery required dual-AAV split-intein systems due to AAV's ~4.7 kb limit. This paper built size-optimized single-AAV genomes encoding compact adenine base editors. Single-AAV ABEs gave up to 66% liver editing in mice and 93% average Pcsk9/Angptl3 knockdown.
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Key findings
Abstract
The viral delivery of base editors has been complicated by their size and by the limited packaging capacity of adeno-associated viruses (AAVs). Typically, dual-AAV approaches based on trans-splicing inteins have been used. Here we show that, compared with dual-AAV systems, AAVs with size-optimized genomes incorporating compact adenine base editors (ABEs) enable efficient editing in mice at similar or lower doses. Single-AAV-encoded ABEs retro-orbitally injected in mice led to editing efficiencies in liver (66%), heart (33%) and muscle (22%) tissues that were up to 2.5-fold those of dual-AAV ABE8e, and to a 93% knockdown (on average) of human PCSK9 and of mouse Pcsk9 and Angptl3 in circulation, concomitant with substantial reductions of plasma cholesterol and triglycerides. Moreover, three size-minimized ABE8e variants, each compatible with single-AAV delivery, collectively offer compatibility with protospacer-adjacent motifs for editing approximately 82% of the adenines in the human genome. ABEs encoded within single AAVs will facilitate research and therapeutic applications of base editing by simplifying AAV production and characterization, and by reducing the dose required for the desired level of editing.