Rapid identification of a tobacco mosaic virus epitope by using a coat protein gene-fragment-pVIII fusion library

This study describes the identification of the epitope recognized by the tobacco mosaic virus (TMV) coat protein (CP)-specific monoclonal antibody 29 (MAb29) by displaying a CP gene-fragment library on pVIII of filamentous phage M13. More than 80% of the clones isolated after one round of panning bound specifically to MAb29. DNA sequencing of ten randomly chosen MAb29-specific clones and subsequent sequence comparison revealed a common seven amino acid epitope (ELIRGTG) representing amino acids 131-137 of the TMV CP. The reactivity of MAb29 in competition ELISA towards glutathione S-transferase fused to this epitope was stronger than that towards full-length wild-type TMV CP, confirming the epitope sequence determined by gene-fragment phage display. This demonstrated that gene-fragment libraries displayed on the phage surface as fusion proteins with the filamentous bacteriophage gene VIII are useful tools for rapid identification of linear epitopes recognized by MAbs.