Expression of human papillomavirus type 16 major capsid protein L1 in transgenic Arabidopsis thaliana

Plants are currently used as a cost-effective and safe heterologous expression system for the production of experimental vaccines. Here, we describe the expression of the HPV16 L1 protein in Arabidopsis thaliana. The HPV16 major capsid gene L1 sequence was extracted by digestion from the plasmid pMOS-L1 HPV16 containing the template sequence and cloned into the binary vector pBI121 consecutively to obtain the plant expression plasmid pBI-L1. The T-DNA regions of the pBI-L1 binary vector were cloned under the control of the constitutive cauliflower mosaic virus 35S promoter and the neomycin phosphotransferase nptII gene; the vector allowed the selection of transformed plants using kanamycin. The Arabidopsis plants were transformed by floral dip method, using Agrobacterium tumefaciens GV3101, which harbored the plant expression plasmid. The generated transgenic Arabidopsis plants were selected on a kanamycin-added Murashige-Skoog medium, and the integration and the stability of the L1 gene in plant genome were confirmed by polymerase chain reaction (PCR) amplification in three successive generations. The evidence for mRNA expression was acquired by reverse transcriptase PCR analysis. To identify further integration of transgene into the genome of A. thaliana, Southern blot assay was carried out and showed that the HPV16 L1 gene was integrated stably into the genome of the transformed Arabidopsis plants. Further-more, Western blot analysis showed that transformed Arabidopsis plants produce HPV16 L1 protein. Thus, HPV16 L1 protein expressed in transgenic Arabidopsis plants can be potentially used as an edible vaccine.