摘要
The mature Shiga toxin B （StxB） gene was optimized and generated by overlapping PCR. Recombinant expression vector pQE40-DHFR/StxB was constructed when the gene was cloned into pQE fusion expression vector. Induced by Isopropyl β-D-thiogalactoside （IPTG）, the DHFR/StxB fusion protein was highly expressed to the level of 41.36% in E. coli MI5 cells. The 35 kDa fusion protein with a 6 His-tag was one-step purified from inclusion bodies using Ni-NTA affinity chromatography column under denaturing conditions, and was refolded by dialyzing with a decreasing urea gradient. Purified DHFR/StxB fusion protein was used to immunize Kunming mice for generating the ascitic polyclonal antibody against recombinant StxB protein by injecting sarcoma 180 cells and the titer ofascitic polyclonal antibody is up to 1： 1× 10^6 detected by the indirect enzyme linked immunosorbent assy （ELISA）. Western immunoblotting analysis revealed that the ascitic polyclonal antibody against StxB had a specific affinity for a 70 kDa shiga toxin protein of Shigella dysenteriae type 1. It is a new simple and quick method to produce a large amount of ascitic polyclonal antibody. The antibody is used to develop immunological method for detecting shiga toxin.
