[Synthesis of dominant epitopes on N-terminal part of BPI and preparation of corresponding antisera].

Aim: To synthesize B cell dominant epitopes on N-terminal part of bactericidal/permeability increasing protein (BPI) and prepare the corresponding antisera.

Methods: The antigenicity, hydrophilicity, flexibility, surface probability and secondary structure of N-terminal amino acids 1-199 on BPI were predicted by bioinformatics applications. Two antigen peptides TA/IK were designed and synthesized on the basis of the above analysis. Then the TA/IK were respectively conjugated to keyhole limpet hemocyanin (KLH) and injected into rabbits to prepare corresponding antisera. Indirect ELISA was performed to analyze the antigenicity of TA/IK and to test the titer of the antisera. And Western blot was used to identify the specificity of the antisera.

Results: (1) Two B cell epitope-based peptides TA/IK were successfully synthesized; (2) the peptides could bind to commercial polyclonal antibody, anti-BPI(55); (3) titers of the antisera against TA/IK were up to 1:51,200, 1:25,600, respectively; (4) Western blot analysis revealed that these antisera could specifically react with the standard sample of BPI(55).

Conclusion: The two synthetic antigen peptides TA/IK are indeed dominant epitopes of BPI N-terminal part, and the corresponding antisera are competent for detecting and identifying the N-terminal fragments of BPI.