UMass Chan Medical School Faculty Publications

UMMS Affiliation

RNA Therapeutics Institute; Department of Molecular, Cell and Cancer Biology; Program in Molecular Medicine; Horae Gene Therapy Center; Viral Vector Core; Department of Microbiology and Physiological Systems; Li Weibo Institute for Rare Diseases Research; Graduate School of Biomedical Sciences

Publication Date


Document Type

Article Preprint


Genetics and Genomics | Molecular Biology | Therapeutics | Viruses


Base editors (BEs) have opened new avenues for the treatment of genetic diseases. However, advances in delivery approaches are needed to enable disease targeting of a broad range of tissues and cell types. Adeno-associated virus (AAV) vectors remain one of the most promising delivery vehicles for gene therapies. Currently, most BE/guide combinations and their promoters exceed the packaging limit (~5 kb) of AAVs. Dual-AAV delivery strategies often require high viral doses that impose safety concerns. In this study, we engineered an adenine base editor using a compact Cas9 from Neisseria meningitidis (Nme2Cas9). Compared to the well-characterized Streptococcus pyogenes Cas9-containing ABEs, Nme2-ABE possesses a distinct PAM (N4CC) and editing window, exhibits fewer off-target effects, and can efficiently install therapeutically relevant mutations in both human and mouse genomes. Importantly, we show that in vivo delivery of Nme2-ABE and its guide RNA by a single-AAV vector can efficiently edit mouse genomic loci and revert the disease mutation and phenotype in an adult mouse model of tyrosinemia. We anticipate that Nme2-ABE, by virtue of its compact size and broad targeting range, will enable a range of therapeutic applications with improved safety and efficacy due in part to packaging in a single-vector system.


AAV, base editing, genome editing, CRISPR, sgRNA, deaminase, gene therapy

Rights and Permissions

The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license.

DOI of Published Version



bioRxiv 2021.12.13.472434; doi: Link to preprint on bioRxiv.


This article is a preprint. Preprints are preliminary reports of work that have not been certified by peer review.

Related Resources

Now published in GEN Biotechnology doi: 10.1089/genbio.2022.0015

Journal/Book/Conference Title


Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.