Neuronal affinity of a C7C loop peptide identified through phage display.

Phage display is a promising tool for the screening of peptides with high affinity for specific cells. Here we describe a novel peptide with neuronal affinity isolated from a C7C library. We designed a two-tiered biopanning strategy initially selecting for ganglioside binding and subsequently selecting for binding to PC12 cells. At the completion of biopanning, 54.8% of phage clones bore the identical peptide (Tet.C7C.1). Immunofluorescence confirmed selective binding of this clone to differentiated PC12 cells. Tet.C7C.1 was synthesized and fluorescein conjugated. The synthetic peptide binds neuronal cell lines (SH-SY5Y, NSC-34 and PC12 cells) and tissue (DRG and spinal cord). The C7C structure creates a loop that minimizes the impact of peptide insertion on the confirmation of the recipient protein. Small loop peptides have the ideal characteristics for modification of viral vector capsids without undermining genome packaging. The neuronal binding properties of this peptide may be applied in the development of neurotropic viral vectors.