Construction of a phage display random decapeptide library and panning for mimic antigen epitope of ScFv A1 against WSSV

A phage display random decapeptide library with high titer was constructed using pCANTAB 5 E as vector and used to select and identify antigen epitopes. ScFv Al, which specifically binds the shrimp's White spot syndrome virus (WSSV), was used to pan against the decapeptide library and a random 15mer library, respectively. A series of positive clones that bind specifically to scFv Al were obtained. The amino acid sequences of the positive peptides were compared with WSSV388 fragment, which is the antigen of scFv Al. We found that most of the sequences of the positive peptides were similar to a fragment, K center dot center dot center dot center dot R center dot center dot R center dot Q, located on C-terminal of WSSV388 fragment. We deduced that the mimic antigen epitopes of scFv Al were conformational epitopes structured by the discontinuous amino acid fragment, but not by a linear amino acid fragment. These results show that phage display peptide library technology is a powerful method for analyzing the structure of antigen epitopes, which is helpful to further explore conformation and function of the structural proteins of WSSV, and the mechanisms of interactions of the virus with the antiviral antibodies and host cells