Disclosed are improved recombinant adeno-associated viral (rAAV) vectors having mutations in one or more capsid proteins. Exemplary vectors are provided that have altered affinity for heparin or heparin sulfate, as well as vectors, expression systems, and rAAV virions that lack functional VP2 protein expression, but are nevertheless, fully virulent. Also provided by the invention are rAAV vector-based compositions, virus particles, host cells, and pharmaceutical formulations that comprise them useful in the expression of selected therapeutic proteins, polypeptides, peptides, antisense oligonucleotides and/or ribozymes in selected mammals, including organs, tissues, and human host cells.