Characterization of BoHV-1 gE envelope glycoprotein mimotopes obtained by phage display

A phage-displayed peptide library was screened using four mAbs directed against bovine herpesvirus 1 (BoHV-1) gE glycoprotein to identify peptides mimicking this glycoprotein. The selected mimotopes allowed us to characterize the epitopes corresponding to the mAbs as continuous and proteinic and to consider using these peptides in further studies. One epitope has been clearly located at the C-terminus of the protein (amino-acids 561-569). The three other mAbs enabled us to stress the immunogenic relevance of the proline-rich motifs of gE. Selected peptides showed no clear sequence identity with gE, but there is a clear link between gE proline-rich regions and the amino-acid composition of the mimotopes. The proline-rich motifs of gE are potentially located in flanking regions involved in the gE/gl glycoprotein complex formation. N-terminal fusion to pill or pVIII filamentous phage protein, C-terminal fusion to the T7 phage capsid protein, biotinylated synthetic peptides and insertion between the non-cleaved CX leader sequence and the C-terminal part of Caulobacter crescentus RsaA protein have been tested in order to increase the valency of a model peptide. We have diverted the C. crescentus expression system and proven its usefulness using the RsaA protein as a scaffold displaying the peptides of interest. Comparison between these different display systems in an indirect ELISA, indicates that the C. crescentus expression and the T7 phage display systems have some major advantages.