High-risk human papillomaviruses (hr-HPVs) cause cervical cancer， the fourth most common cancer in women worldwide. A HPV-16 candidate therapeutic vaccine， LALF32-51-E7， was developed by fusing a modified E7 protein to a bacterial cell-penetrating peptide (LALF): this elicited both tumour protection and regression in pre-clinical immunization studies. In the current study， we investigated the potential for producing LALF32-51-E7 in a plant expression system by evaluating the effect of subcellular localization and usage of different expression vectors and gene silencing suppressors. The highest expression levels of LALF32-51-E7 were obtained by using a self-replicating plant expression vector and chlorop... More
High-risk human papillomaviruses (hr-HPVs) cause cervical cancer， the fourth most common cancer in women worldwide. A HPV-16 candidate therapeutic vaccine， LALF32-51-E7， was developed by fusing a modified E7 protein to a bacterial cell-penetrating peptide (LALF): this elicited both tumour protection and regression in pre-clinical immunization studies. In the current study， we investigated the potential for producing LALF32-51-E7 in a plant expression system by evaluating the effect of subcellular localization and usage of different expression vectors and gene silencing suppressors. The highest expression levels of LALF32-51-E7 were obtained by using a self-replicating plant expression vector and chloroplast targeting， which increased its accumulation by 27-fold compared to cytoplasmic localization. The production and extraction of LALF32-51-E7 was scaled-up and purification optimized by affinity chromatography. If further developed， this platform could potentially allow for the production of a more affordable therapeutic vaccine for HPV-16. This would be extremely relevant in the context of developing countries， where cervical cancer and other HPV-related malignancies are most prevalent， and where the population have limited or no access to preventative vaccines due to their typical high costs.
