Mapping administration route-dependent transduction profiles of commonly used AAV variants in mice by barcode amplicon sequencing

The tissue transduction profiles and transgene expression efficiencies of adeno-associated viruses (AAVs) depend not only on the utilized capsid and dose but also on the administration route. Yet, despite the plethora of available natural and capsid-engineered variants, a comprehensive evaluation of the administration route dependency of AAV tropism has been lacking so far. Therefore, we here compared transduction and transgene expression profiles for 34 well-known AAV capsids following intravenous (i.v.) and intraperitoneal (i.p.) injection in male C57BL/6 mice by multiplexed biodistribution analyses based on AAV genome-barcoding. Readout on viral genome and transcript level confirmed pronounced liver targeting by most AAV variants after i.v. administration, as well as known tissue tropism for benchmark capsids (e.g., AAV-PHP.eB: brain and AAV2-ESGHGYF: lung). In contrast, i.p. administration generally decreased liver targeting, while concurrently increasing expression in other abdominal organs in a capsid-specific fashion. For example, AAV6.2 and AAV-DJ, which showed almost exclusive liver transduction after i.v. administration, displayed differential biodistribution profiles with enhanced expression in the diaphragm, adipose tissue, and pancreas when administered intraperitoneally. In summary, our data guide study design by enabling the selection of optimal vector and administration route combinations for refined tissue targeting approaches in preclinical <i>in vivo</i> experiments.