[Screening of mimic antigen epitopes of Echinococcus granulosus by phage-displayed peptide library]

The 7-mer phage random peptide libraries was screened with the specific anti-EgB polyclonal antibody. Sixty clones picked randomly were deduced by DNA sequencing and their amino acid sequences were compared with EgB. After 5 rounds of panning, the phage recovery rate increased from 4.15 x 10(-5) to 4.30 x 10(-2). 45 out of 60 selected clones were ELISA positive by anti-EgB polyclonal antibody with a positive rate of 75%, 45 positive clones were sequenced and the predicted amino acid sequences showed low homology to EgB. The reactivity of selected peptide and sera from patients of anaphylactic shock induced by Echinococcus granulosus was detected by ELISA. The result showed that the absorbance value (A410) of 45 positive clones detected by using serum samples from patients was twice higher than that by using 7 peptide library. The 45 positive clones exhibited specific binding to anti-EgB antibody. The peptides screening from 7-mer phage random peptide libraries may be the mimic epitopes of anaphylactic shock induced by E. granulosus.