Objective      To construct the expression vector of bactericidal/permeability-increasing protein (BPI)-LL37 antibacterial fusion protein and prepare the antibacterial fusion protein

so as to explore a novel clinical intervention strategy for curing sepsis.       Methods      PCR was used to obtain rBPI

21

and LL3

7 active segments from cDNA of BPI gene and LL37 gene. The rBPI

21

and LL37 DNA segments were linked with a flexible linker (GGSGG) and cloned into expression vector pLVX-Tight-Puro

and then the recombinant vector was transferred into A549 cells using PolyJet

TM

in vitro DNA transfection reagent. The expression of the antibacterial fusion protein in the A549 cells was identified by Western blotting

and the antibacterial efficacy was assayed by bacterial inhibitory test.       Results      Expression vector pLVX-Tight-Puro-BPI-LL-37 was successfully constructed and identified by DNA electrophoresis after restriction enzyme digestion and DNA sequencing. Western blot assay showed that rBPI

21

-LL37/LL37-rBPI

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fusion protein [(25-30)×10

3

]

was stably expressed in the A549 cells. The bacterial inhibition test showed that the fusion protein could inhibit bacterial growth.       Conclusion      The expression vector pLVX-Tight-Puro-BPI-LL-37 is successfully constructed and introduced into human somatic cells to secrete fusion protein with antibacterial activity

and the fusion protein may be potential drug for treating sepsis.