[Screening of short peptides binding to StxB by phage-display library]

Under induction with 41 degrees C, pBV220-stxb/DH5alpha expressed the recombinant protein Shiga Toxin B Subunit (StxB), which was purified by centrifugation, salting out and ion exchange chromatography. As a target, the purified-protein-coated ELISA plate was used to screen phages able to bind onto it from a random 12-mer peptide library. After 4 rounds of affinity screening, a group of clones were isolated from the peptide library. ELISA assay detected their binding activity with the target. 27 clones showed the specific binding activity. The peptide sequences of these positive phage clones were analyzed. 16 of them had the same sequence named A6, 2 clones had the A9 sequence, and 3 clones had the A3 sequence. To evaluate the neutralization effect of A6 phage, animal test was carried out. The Shiga Toxin was incubated with A6 phage clone, then used to attack the Balb/C mice. As a control, the toxin was incubated with negative phage. In the control group, no mice survived. Comparing with it, the survival rate of the mice in neutralization group could reach to a level of 33.3%. It showed that the toxicity of Shiga Toxin was partly inhibited. The A6 peptide could be developed as an inhibitor of Shiga Toxin to cure the diseases caused by Shiga Toxin.