Construction, Identification, and Expression of Lactococcus lactis-Based Recombinant Vaccine for Echinococcus granulosus

  Objective  To construct Lactococcus lactis (LL)-based recombinant LL-Eg95 (rLL-Eg95) vaccine for Echinococcus granulosus (Eg) and to examine its expression efficiency.

  Methods  Eg95 gene was obtained by PCR from the template of pCD-Eg95. Then, pMG36e was inserted in the Eg95 gene after double cleaving with restriction endonucleases XbaⅠ and HindⅢ to construct recombinant plasmid pMG36e-Eg95, which was transformed into E.coli BL2 (DE3) competent cells. The recombinant plasmid was extracted and identified by double restriction endonuclease digestion and was then electroporated into LL MG1363 to construct rLL-Eg95 vaccine. Then, the plamid was extracted and identified by PCR.

  Results  Examination of the recombinant plasmid by double restriction endonuclease digestion showed that the segment was of the expected length. PCR showed that 471 base pairs of Eg95 gene were amplified when the plasmid extracted from roxithromycin-resistant recombinant LL was used as the template. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the relative molecular mass of the Eg95 protein expressed was approximately 16.5×10³ and that the amount of the expressed protein was 17% of the total bacterial proteins. Western blot findings suggested that the expressed protein could be recognized by mice serum infected with hydatid cyst.

  Conclusion  The rLL-Eg95 vaccine was successfully constructed, expressing Eg95 protein that has specific antigenicity.