Identification of a porcine TLR2-targeting peptide ligands using a cell-based phage display combined with high-throughput sequencing

Abstract M cell targeting is one of the critical issues to develop efficient mucosal vaccine design. In this study, peptide ligands with high affinity to porcine TLR2, which is highly expressed in M cells and play an important role in mucosal immune responses in pigs, were identified through the cell-based phage display technique combined with high-throughput sequencing. A random phage-peptide library was applied to the porcine TLR2 overexpressing cell line and total 85, 557 unique peptide sequences were identified from approximately 9.0 × 107 reads after three rounds of both subtractive and non-subtractive biopanning via high-throughput sequencing. Among the unique sequences, three candidate peptide sequences, NAGHLSQ, VPSKPGL, and RANLDGQ, were selected based on their abundance in the third round of biopanning. Consequently, NAGHLSQ showed the highest affinity exclusively to porcine TLR2 compared with other candidates and its binding mechanism was inferred to be directly associated with ligand binding site of the TLR2 through the in vitro competitive analysis. The peptide identified in this research could be used in development of effective porcine mucosal vaccine as an M cell targeting moiety to enhance the transport of antigens into the Peyer's patch via oral route.