Virosome-mediated delivery of protein antigens to dendritic cells.

Virosomes are reconstituted viral membranes in which protein can be encapsulated. Fusion-active virosomes, fusion-inactive virosomes and liposomes were used to study the conditions needed for delivery of encapsulated protein antigen ovalbumin (OVA) to dendritic cells (DCs) for MHC class I and II presentation. Fusion-active virosomes, but not fusion-inactive virosomes, were able to deliver OVA to DCs for MHC class I presentation at picomolar OVA concentrations. Fusion activity of virosomes was not required for MHC class II presentation of antigen. Therefore, virosomes are an efficient system for delivery of protein antigens for stimulation of both helper and CTL responses.