Presentation of functional foreign peptides on the surface of SV40 virus-like particles.

Viral capsids of simian virus 40 (SV40) are highly efficient gene delivery vehicles that infect a broad range of cells and tissues. To develop a controlled, cell type-specific delivery system, we sought to display foreign peptides on the capsid surface by genetically manipulating the major capsid protein Vp1. Here we report the identification of two sites within the surface loops of Vp1 that can accommodate foreign peptides in such a way that the foreign peptides are displayed on the surface of the virus-like particles (VLPs) without interfering with VLP assembly or the packaging of viral DNA. Insertion of Flag-tags but not RGD integrin-binding motifs at these sites strongly inhibited cell attachment of VLPs, which normally associate with host cells through cell surface molecules such as major histocompatibility complex (MHC) class I and ganglioside GM1. Instead, VLPs carrying the RGD motifs bound to integrin in vitro and to the cell surface in an RGD-dependent manner. Thus, insertion of foreign sequences into the surface loops of Vp1 can reduce natural virus-cell interactions and even confer an ability to bind to a new target receptor. This study demonstrates the potential usefulness of this strategy for the development of novel delivery vehicles with different cell tropisms.