Selector adeno-associated viral vectors facilitate on-target precise genome editing and purge off-target chromosomal insertions

Adeno-associated viral (AAV) vectors are commonly used for genome editing owing to the proclivity with which their single-stranded genomes serve as homologous recombination (donor) substrates during programmable nuclease-assisted gene targeting. However, the highly recombinogenic nature of AAV genomes also facilitates their nonhomologous end joining at off-target chromosomal breaks ('capture') created by said nucleases, mutagens, or DNA metabolic processes. Moreover, AAV donor constructs can equally yield imprecise on-target edits resulting from end-joining recombination pathways. Here, we demonstrate that endowing AAV vectors with exogenous marker-free selectable sequences permits enrichment for cells precisely coedited at endogenous target and ATP1A1 alleles. These selector AAV vectors install ATP1A1 polymorphisms conferring resistance to the small molecule ouabain, yielding high frequencies of on-target and precisely edited cell populations. Crucially, we further report that selector AAV vectors achieve a thorough removal of heterogeneous off-target DNA species resulting from conventional AAV-based genome editing procedures.