ABSTRACT
<p><b>OBJECTIVE</b>To establish an improved procedure for isolation and identification of epitopes from a random peptide library displayed on the bacterial surface.</p><p><b>METHODS</b>Epitopes were screened from FliTrx random peptide library by a monoclonal antibody 3B9 against HBV-PreS2 protein. The enrichment was monitored in each round. Higher affinity clones were obtained by increasing the washing strength and randomly selected for sequencing and Western blot analysis.</p><p><b>RESULTS</b>Clones specifically binding to antibody were enriched in each round. Ten sequences were obtained from sixteen sequenced clones, seven of them contained the common motif RXRGXY with high homogeneity to 135-140 amio acids in HBV-PreS protein and have positive results in Western blot analysis. The other three sequences have no typical motif RXRGXY and showed different Western blot results.</p><p><b>CONCLUSIONS</b>It's easy and quick to drive epitopes from a random peptide library displayed on the bacterial surface.</p>