{"doi":"10.1016/j.ymthe.2020.04.017","title":"AAV-CRISPR Gene Editing Is Negated by Pre-existing Immunity to Cas9","abstract":"Adeno-associated viral (AAV) vectors are a leading candidate for the delivery of CRISPR-Cas9 for therapeutic genome editing in vivo. However, AAV-based delivery involves persistent expression of the Cas9 nuclease, a bacterial protein. Recent studies indicate a high prevalence of neutralizing antibodies and T cells specific to the commonly used Cas9 orthologs from Streptococcus pyogenes (SpCas9) and Staphylococcus aureus (SaCas9) in humans. We tested in a mouse model whether pre-existing immunity to SaCas9 would pose a barrier to liver genome editing with AAV packaging CRISPR-Cas9. Although efficient genome editing occurred in mouse liver with pre-existing SaCas9 immunity, this was accompanied by an increased proportion of CD8+ T cells in the liver. This cytotoxic T cell response was characterized by hepatocyte apoptosis, loss of recombinant AAV genomes, and complete elimination of genome-edited cells, and was followed by compensatory liver regeneration. Our results raise important efficacy and safety concerns for CRISPR-Cas9-based in vivo genome editing in the liver. Adeno-associated viral (AAV) vectors are a leading candidate for the delivery of CRISPR-Cas9 for therapeutic genome editing in vivo. However, AAV-based delivery involves persistent expression of the Cas9 nuclease, a bacterial protein. Recent studies indicate a high prevalence of neutralizing antibodies and T cells specific to the commonly used Cas9 orthologs from Streptococcus pyogenes (SpCas9) and Staphylococcus aureus (SaCas9) in humans. We tested in a mouse model whether pre-existing immunity to SaCas9 would pose a barrier to liver genome editing with AAV packaging CRISPR-Cas9. Although efficient genome editing occurred in mouse liver with pre-existing SaCas9 immunity, this was accompanied by an increased proportion of CD8+ T cells in the liver. This cytotoxic T cell response was characterized by hepatocyte apoptosis, loss of recombinant AAV genomes, and complete elimination of genome-edited cells, and was followed by compensatory liver regeneration. Our results raise important efficacy and safety concerns for CRISPR-Cas9-based in vivo genome editing in the liver.","journal":"Molecular Therapy","year":2020,"id":49808,"datarank":5.818750591458016,"base_score":5.438079308923196,"endowment":5.438079308923196,"self_citation_contribution":0.8157118963384794,"citation_network_contribution":5.003038695119537,"self_endowment_contribution":0.8157118963384794,"citer_contribution":5.003038695119537,"corpus_percentile":null,"corpus_rank":null,"citation_count":229,"citer_count":200,"citers_with_citation_signal":177,"citers_with_endowment":177,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9504,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":241976,"name":"Mark R. Tanner","orcid":"0000-0002-6516-0166","position":1,"is_corresponding":false},{"id":241977,"name":"Ciaran M. Lee","orcid":"0000-0002-0789-9149","position":2,"is_corresponding":false},{"id":241978,"name":"Ayrea Hurley","orcid":"0000-0002-8697-8610","position":3,"is_corresponding":false},{"id":241979,"name":"Marco De Giorgi","orcid":"0000-0002-9823-1397","position":4,"is_corresponding":false},{"id":241980,"name":"Kelsey E. Jarrett","orcid":"0000-0001-5358-8280","position":5,"is_corresponding":false},{"id":164299,"name":"Timothy Davis","orcid":"0000-0003-2302-5203","position":6,"is_corresponding":false},{"id":241981,"name":"Alexandria M. Doerfler","orcid":"0000-0003-2297-6103","position":7,"is_corresponding":false},{"id":241982,"name":"Gang Bao","orcid":"0000-0001-5501-554X","position":8,"is_corresponding":false},{"id":241983,"name":"Christine Beeton","orcid":"0000-0002-2500-5874","position":9,"is_corresponding":false},{"id":241984,"name":"William R. Lagor","orcid":"0000-0002-1703-5125","position":10,"is_corresponding":false},{"id":241975,"name":"Ang Li","orcid":"0000-0002-8992-3914","position":0,"is_corresponding":true}],"reference_count":40,"raw_metadata":{"citation_network_status":"fetched"},"created_at":"2026-07-18T20:37:28.027635Z","pmid":"32348718","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}