利用噬菌体随机肽库筛选可结合志贺毒素B亚单位的短肽序列

以制备的重组志贺毒素B亚单位(StxB)为靶标,利用噬菌体展示亲和淘选技术,经4轮筛选,从随机十二肽库中筛选到与StxB结合的一批噬菌体克隆,对特异结合活性较高的27个噬菌体克隆的表面展示肽进行序列测定,其中A6序列出现16次,A9和A3序列分别出现2次和3次。为评价筛选克隆中和毒素毒性的能力,将展示肽出现频率最高的A6噬菌体克隆,体外与志贺毒素孵育进行动物试验,动物存活率达33.3%,表明毒素的毒性得到部分抑制,A6短肽可能发展成为志贺毒素的拮抗剂。

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.