Cloning and Expression of the Lactate Dehydrogenase Gene of Plasmodium falciparum and the Immunogenicity Characterization of its Expressed Product

Objective:To clone and express the lactate dehydrogenase(LDH) gene of Plasmodium falciparum(p.f) FCC1/HN isolate and to identify the immunogenicity of the recombinant protein.Methods:The LDH gene of p.f was specifically amplified by PCR and cloned into prokaryotic expression vector pET-32a(+),the recombinant plasmid was transferred into competent E.coli BL21(DE3),positive clones were screened and identified by direct colony PCR,restriction enzyme digestion and sequencing.Then the recombinant vector was induced and expressed in E.coli BL21(DE3).Rabbits were immunized with the purified protein and the anti-LDH immunosera were prepared.Indirect immunofluorescence assay and Western-blot was carried out to assess the immunogenicity of the recombinant protein.Results:The recombinant expression vector pET-32a/LDHpf was successfully constructed.DNA sequence analysis indicated the homology of LDH genes of different p.f isolates reached more than 98%,and of different species of plasmodium was also up to 90%.Indirect immunofluorescence assay and Western-blot analysis showed the recombinant protein exhibited a better immunogenicity.Conclusion:Sequence analysis showed the LDH gene of p.f was quite conserved and the recombinant protein was highly expressed in the E.coli BL21 and indirect immunofluorescence assay and western-blot analysis indicated that the recombinant protein had a good immunogenicity.