Aspects of the disclosure relate to compositions and methods for delivering a transgene (e.g., a transgene encoding one or more gene products) to a target cell. The disclosure is based, in part, on adeno-associated virus (AAV) capsid protein variants characterized by tropisms for certain cell types (e.g., neurons, muscle cells, bone cells, heart cells, etc.). In some embodiments, recombinant A A Vs (rAAVs) comprising the capsid protein variants (e.g., AAVv66, SEQ ID NO: 1) are more efficiently packaged than rAAVs having certain wild-type AAV capsid proteins. Methods of delivering an rAAV comprising the AAV capsid protein variants are also described by the disclosure.