The invention relates to adeno-associated virus (AAV) serotype AAV-Rh74 and related AAV vectors, and AAV-Rh74 and related AAV vector mediated gene transfer methods and uses. In particular, AAV-Rh74 targets polynucleotides to cells, tissues or organs for expression (transcription) of genes encoding therapeutic proteins and peptides, and polynucleotides that function as or are transcribed into inhibitory nucleic acid sequences.