Preparation and identification of anti-human ICAM-1 scFv / 生物工程学报

To screen the specific anti-human intercellular adhesion molecule-1 (ICAM-1) single chain fragment variable (scFv) using phage display library technology and to identify its biological activity. P1 peptide was used as antigen, and the phage antibodies against human ICAM-1 antigen were panned by four binding-eluting-amplifying cycles using Tomlinson I+J phage display library. After four rounds of selective enrichment screening, the positive clones were determined by PCR, enzyme linked immunosorbent assay (ELISA)-based antigenic cross reaction and Dot blotting. Then the binding specificity and biological activity of purified scFv were identified by Western blotting, competitive ELISA and cell adhesion inhibition assay respectively. Furthermore, four positive clones were first panned through P1 peptide coated-ELISA assay, and then J-A1 was obtained and identified by PCR, ELISA-based antigenic cross reaction and Dot blotting, which could show a specific binding between P1 peptide and human ICAM-1 protein antigen. Subsequently, the purified scFv showed a satisfactory specificity and anti-adhesive activity in competitive ELISA and the cell adhesion inhibition assay. The specific anti-human ICAM-1 scFv was prepared successfully from Tomlinson I+J phage display library, which pave the way for further application of anti-human ICAM-1 scFv for inflammation diseases therapeutics.

Primary determination for activity and expression of Stx 2a’-LHRH chimeric toxin / 中国病理生理杂志

AIM: To express chimeric toxin Stx2a’-LHRH a nd to investigate the cytotoxic activity of recombinant toxin Stx2a’-LHRH to huma n carcinoma cells.METHODS: Stx2a’-LHRH sequences that added the res tri ction endonucleases NcoⅠ and EcoRⅠ at the 5' and 3 ends were amplified by PCR a nd digested with appropriate restriction enzymes. The digested fragment was subc loned into the vector obtatined by digestion of plasmid pET-28a(+) with NcoⅠ an d EcoRⅠ. E. coli BL21 (DE3) cells were transformed with plasmids of interst and cultured in LB medium containing ampicillin. Expression of the recombinant protein was induced by the addition of isopropylthio-?-D-galactoside (IPTG). T h e cytotoxity of Stx2a’-LHRH to Hep-2 cells was observed under the microscop y. RESULTS: Recombitant plasmid pET-SL was constructed successfu lly and the clones expressing pET-SL stablely were obtained. A special electroph oretic band in SDS-PAGE (a glycoprotein of 28kD) was noted. Stx2a’-LHRH killed He lp-2 cells clearly. CONCLUSION: In this study, construction of c himeric toxin Stx2a’-LHRH and its expression were described. Moreover, it has o bvious cytotoxity to Hep-2 cell. These finding could open up new vistas in the s tudy of targeted durgs.