Production of HPV۱۶-L۱ through BL۲۱/pET۳۲a expression system

Introduction: The Human papillomaviruses (HPV) main capsid protein L۱ is naturally capable to self-assemble as virus-like particles (VLPs). There are different recombinant protein expression systems such as bacteria, yeast, insect, plant, and mammalian cells for generation of VLP-based candidate vaccines targeting various pathogens. In this study, we produced HPV-L۱ protein by BL۲۱/pET۳۲a expression system and VLP production was confirmed.Material & Method: The recombinant plasmid pET۳۲/L۱ was transformed into Escherichia. coli BL۲۱ and selected with ampicillin. The positive clones containing the recombinant plasmid pET۳۲/L۱ were assessed by restriction endonucleases HindIII and XhoI and sequence analysis. The expression of HPV۱۶-L۱ fusion protein in E. coli BL۲۱was identified by SDS-PAGE and Western blotting. VLPs were evaluated using electron microscopy.Result: A codon-optimized L۱ gene was expressed in BL۲۱ under the control of the T۷/lac promoter. Purification of L۱ protein was achieved after Ni NTA chromatography. The ۶۰kDa protein was detected in the lysates of BL۲۱, recognized as HPV۱۶- L۱ protein by Western blotting. VLPs were confirmed using electron microscopy.Conclusion: In this study, we established a high-efficient recombinant E. coli expression system for the production of HPV ۱۶- L۱ protein. The generated L۱ protein was correctly self-assembled into VLPs. Therefore, BL۲۱/pET۳۲a as a prokaryotic expression system is a potent tool for HPV۱۶-L۱ VLP production.