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.

碱基编辑器的病毒传递因其大小和腺相关病毒（AAV）有限的包装能力而变得复杂。通常，已经使用基于反式剪接内含子的双AAV方法。在这里，我们表明，与双 AAV 系统相比，具有尺寸优化基因组并结合紧凑腺嘌呤碱基编辑器 (ABE) 的 AAV 能够以相似或更低的剂量在小鼠中进行有效的编辑。向小鼠眼眶后注射单 AAV 编码的 ABE，肝脏 (66%)、心脏 (33%) 和肌肉 (22%) 组织的编辑效率高达双 AAV ABE8e 的 2.5 倍，循环中人类 PCSK9 和小鼠 Pcsk9 和 Angptl3 的敲低（平均）达 93%，同时血浆胆固醇和甘油三酯大幅降低。此外，三个尺寸最小化的 ABE8e 变体，每个都与单 AAV 传递兼容，共同提供与原型间隔子相邻基序的兼容性，用于编辑人类基因组中约 82% 的腺嘌呤。单个 AAV 中编码的 ABE 将通过简化 AAV 的生产和表征以及减少所需编辑水平所需的剂量，促进碱基编辑的研究和治疗应用。