Abstract: Objective To construct and express a fusion gene of fatty acid binding protein （FABP） with Eg95 which are protective antigen genes of Echinococcus granulosus, and investigate the immunological characteristics of the recombinant protein. Method Using cDNA fragments encoding FABP and Eg95 genes from E. granulosus Qinghai sheep strain as templates, a fusion gene FABP·Eg95 was amplified by asymmetric polymerase chain reaction through a linking sequence encoding four glycine residues. The PCR products of fusion gene were subcloned into the pET28a （+） vector. The recombinant plasmid was transformed into Escherichia coli BL21（DE3） cells and induced with IPTG. The recombinant protein was detected by SDS-PAGE and purified by Ni-IDA affinity chromatography, and its immunogenicity was analyzed by Western blotting. Results The fusion gene length was about 795 bp. Double enzyme digestion analysis and DNA sequencing confirmed that the fusioin gene was cloned into pET-28a （+）. The recombinant protein （M_r 31 000） was expressed in inclusion body in E. coli expression system, and was purified by Ni-IDA affinity chromatography. Western blotting analysis testified that the recombinant protein could be recognized by sera of cystic echinococcosis patients, but not by sera of healthy persons and schistosomiasis patients. Conclusion The FABP·Eg95 fusion gene has been constructed, and the purified recombinant protein has been confirmed with immunogenicity.

Key words: Echinococcus granulosus, Eg95, Fatty acid bindding protein, Western blotting