Objective To prepare a mutant DNA of sCD74

the receptor of MIF

by the technique of DNA shuffling and T7 phage display.  Methods Mutated homologous genes of bovine

mouse and human were digested with DNaseⅠ

and DNA about 20-50 bp was extracted from the gel. These DNA fragments were used for DNA shuffling

and mutants about 500 bp were obtained. After digested with restriction enzyme

the mutants about 500 bp were ligated to T7 phage vector

the product of which was packaged with a T7 packaging extracts. Recombinant phage library was amplified and screened by competitive bio-panning method. After 5 rounds of panning

high MIF binding phages were enriched. Plaques were made and 20 single clones were chosen to be sequenced. The result of sequencing was analyzed by bio-informatics software. The competitive ELISA was carried out to check whether the affinity of phage to MIF had been improved.  Results Twenty positive single phage clones have a single consistent sequence

indicating that they are derived from a single clone. This clone is named sHCD74m

while its gene is named sHCD74mD. The result of competitive ELISA showed that sHCD74m prevents natural sCD74 from binding MIF.  Conclusion sHCD74mD

the gene of sCD74 mutant that binds MIF with high affinity

has been made.