Dynamin is required for recombinant adeno-associated virus type 2 infection

Recombinant adeno-associated virus (rAAV) vectors for gene therapy of inher ited disorders have demonstrated considerable potential for molecular medic ine. Recent identification of the viral receptor and coreceptors for AAV ty pe 2 (AAV-2) has begun to explain why certain organs may demonstrate higher efficiencies of gene transfer with this vector, However, the mechanisms by which AAV-2 enters cells remain unknown. In the present report, we have ex amined whether the endocytic pathways of rAAV-2 are dependent on dynamin, a GTPase protein involved in clathrin-mediated internalization of receptors and their ligands from the plasma membrane. Using a recombinant adenovirus expressing a dominant-inhibitory form of dynamin I (K44A), we have demonstr ated that rAAV-2 infection is partially dependent on dynamin function. Over expression of mutant dynamin I significantly inhibited AAV-2 internalizatio n and gene delivery, but not viral binding. Furthermore, colocalization of rAAV and transferrin in the same endosomal compartment provides additional evidence that clathrin-coated pits are the predominant pathway for endocyto sis of AAV-2 in HeLa cells.