cDNA Cloning of Human Lactoferrin and its Expression in BmN Cells

Human lactoferrin cDNA was amplified by RT-PCR from normal human mammary tissue. The comparision with other four hLF cDNA sequences registered in GenBank was shown 99% homology in DNA sequence. The hLF gene was inserted into the baculovirus transfer vector pBacPAK_8, and the recombinant plasmid pBacPAK-hLF was co-transfected with linearized Bm-BacPAK_6 virus DNA into BmN cells, then homologous recombination occurred inside the cells. The recombinant virus BmNPV-hLF was purified three times by screening plaques and identified by Southern blotting. The recombinant human lactoferrin (rhLF) was expressed in BmN cells infected with recombinant virus. The expressed products were run on the 7.5% SDS-PAGE and their immunoreactivities were determined by Western blotting. The highest expression level of rhLF is about 13.5 mg/L in BmN cells. The bioactivities of the recombinant proteins showed its bacteriostasis effect on E.coli JM109.