Production of HPV16-L1 Through BL21/pET32a Expression System

Background: the human papillomavirus (hpv) main capsid protein l1 is naturally capable of self- assembly as virus-like particles (vlps). there are different recombinant protein expression systems, such as bacteria, yeast, insect, plant, and mammalian cells, for the generation of vlp- based candidate vaccines targeting various pathogens. in this study, we produced the hpv16-l1 protein by bl21/pet32a expression system, and vlp production was confirmed. methods: the recombinant plasmid pet32/l1 was transformed into escherichia coli bl21 and selected with ampicillin. the positive clones containing the recombinant plasmid pet32/l1 were assessed by restriction endonucleases hindiii and xhoi and nested polymerase chain reaction (pcr). the expression of hpv16-l1 fusion protein in escherichia coli bl21 was identified by sds- page and western blotting. electron microscopy was used to evaluate vlp formation. results: a codon-optimized l1 gene was expressed in bl21 under the control of the t7/lac promoter. purification of l1 protein was achieved after ni nta chromatography. the 60 kda protein was detected in the lysates of bl21, recognized as hpv16- l1 protein by western blotting. the vlps were confirmed using electron microscopy. conclusion: in this study, we established an efficient recombinant e. coli expression system for the production of hpv 16- l1 protein. the generated l1 protein was correctly self-assembled into vlps. therefore, bl21/pet32a as a prokaryotic expression system is a potent tool for hpv16-l1 vlp production.