Targeting of adenovirus penton base to new receptors through replacement of its RGD motif with other receptor-specific peptide motifs.

The adenovirus coat protein, penton base, contains the peptide motif RGD which mediates binding to the integrin cell surface receptors alpha v beta 3 and alpha v beta 5. These integrins then mediate adenovirus internalization. We have developed penton base chimeras that recognize tissue-specific integrin receptors by replacing the wild-type RGD peptide motif with alpha v beta 3- or alpha 4 beta 1-specific peptide motifs. In one chimera the original haiRGDtfa motif was replaced with the peptide motif eiLDVpst which mediated chimera binding to the integrin alpha 4 beta 1. This integrin is expressed at high levels on lymphocytes and monocytes but is not expressed on epithelial or endothelial cells. In a second chimera the wild-type sequences flanking the RGD motif were altered to abrogate its interaction with alpha v beta 5 while retaining its specificity for alpha v beta 3. The integrin alpha v beta 5 is expressed primarily on epithelial cells whereas the integrin alpha v beta 3 is normally expressed on endothelial cells. The integrin alpha v beta 3 is also aberrantly expressed on certain metastatic melanomas and glioblastomas. A deletion mutant lacking the RGD sequence did not bind to any integrins. Such chimeras incorporated into adenovirus virions may be useful in targeting specific tissues in adenovirus-mediated gene delivery.