Abstract：To express and purify the Mycobacterium tuberculosis latent infection implicated protein (ICL),determine the bidogical activity and prepare the polyclonal antibody against ICL,the gene encoding ICL was amplified by PCR from genome of Mycobacterium tuberculosis H37Rv strain and inserted into prokaryotic expression vector pQE30 to obtain recombinant plasmid pQE30 icl. The recombinant vector pQE30 icl was transformed into E.coli after digestion by restriction endonuclease and sequence analysis, induced with IPTG. The product was analyzed by SDS PAGE and Western blotting. Then the expressed protein was purified by Ni NTA purification system. The enzyme activity of the purified protein was determined. The polyclonal antibody was prepared by immunization with the purified protein in New Zealand rabbits, and the specific antibody titer was determinded by double immunodiffusion.It was found that the sequence of icl obtained by PCR amplification had two nucleotides mutations,both were nonsense mutations.The expressed protein induced by IPTG in E.coli had relative molecular mass of 47 kDa. The Western blotting analysis showed the expressed protein could react with the serum from tuberculosis patients speicfically. The enzyme activity of the purified protein was 16.7u/mg. The specific antibody titer in the serum of rabbits immunized with the purified protein was 1∶32.Mycobacterium tuberculosis latent infection implicated protein ICL with enzyme activity was expressed successfully in E.coli. The polyclonal antibody of ICL was produced successfully in rabbit. Our study established some material foundations for researches against latent infection of Mycobacterium tuberculosis.
