Displaying and epitope mapping of CD147 on VCSM13 phages: influence of Escherichia coli strains.

The external domain of a human leukocyte surface molecule, CD147 was displayed on the surface of phage. Two Escherichia coli laboratory strains, XL-1 Blue and TG-1, were chosen to separately propagate the recombinant phages. By sandwich enzyme linked immunosorbent assay (ELISA), CD147 on phage particles were individually captured by six CD147 mAbs and subsequently detected by anti-M13 conjugated HRP. All mAbs specifically bound the CD147 on phage particles derived from TG-1. On the contrary, only four of them could recognize the CD147 on phages produced by XL-1 Blue. The results indicate that the environment in the TG-1 periplasm is more appropriate than that of XL-1 Blue for promoting the suitable folding of CD147. This finding emphasizes the importance of selecting the appropriate E. coli host for display of a complex protein. The epitopes of CD147 displayed on the phage were further mapped by competitive inhibition ELISA, which is a reliable and economical method. Certain clusters of mAb recognition areas were identified and will provide valuable information for the discovery of the ligand for CD147.