Bioproduction of a Therapeutic Vaccine Against Human Papillomavirus in Tomato Hairy Root Cultures

Abstract

Human papillomavirus (HPV) tumor disease is a critical public health problem worldwide, especially in the developing countries. The recognized pathogenic function of E5, E6, and E7 oncoproteins offers the opportunity to devise therapeutic vaccines based on engineered recombinant proteins. The potential of plants to manufacture engineered compounds for pharmaceutical purposes, from small to complex protein molecules, allows the expression of HPV antigens and, possibly, the regulation of immune functions to develop very specific therapies as a reinforcement to available nonspecific therapies and preventive vaccination also in developed countries. Among plant-based expression formats, hairy root cultures are a robust platform combining the benefits of eukaryotic plant-based bioreactors, with those typical of cell cultures. In this work, to devise an experimental therapeutic vaccine against HPV, hairy root cultures were used to express a harmless form of the HPV type 16 E7 protein (E7*) fused to SAPKQ, a noncytotoxic form of the saporin protein from Saponaria officinalis, that we had shown to improve E7-specific cell-mediated responses as a fusion E7*-SAPKQ DNA vaccine. Hairy root clones expressing the E7*-SAPKQ candidate vaccine were obtained upon infection of leaf explants of Solanum lycopersicum using a recombinant plant expression vector. Yield was approximately 35.5 μg/g of fresh weight. Mouse immunization with vaccine-containing crude extracts was performed together with immunological and biological tests to investigate immune responses and anticancer activity, respectively. Animals were primed with either E7*-SAPKQ DNA-based vaccine or E7*-SAPKQ root extract-based vaccine and boosted with the same (homologous schedule) or with the other vaccine preparation (heterologous schedule) in the context of TC-1 experimental mouse model of HPV-associated tumor. All the formulations exhibited an immunological response associated to anticancer activity. In particular, DNA as prime and hairy root extract as boost demonstrated the highest efficacy. This work, based on the development of low-cost technologies, highlights the suitability of hairy root cultures as possible biofactories of therapeutic HPV vaccines and underlines the importance of the synergic combination of treatment modalities for future developments in this field.

Expression of Human papillomavirus type 52 L1 capsid gene in Oryza sativa involved in cytoprotective activities

“…The production of human β-glucocerebrosidase in Nicotiana benthamiana for the replacement therapy of rare diseases is also reported (Naphatsamon et al, 2018). Recently, Massa et al (2019) illustrated that tomato hairy root cultures were used to express the HPV-16E7 protein fused to the saporin protein from Saponaria officinalis to improve E7-specific cell-mediated responses as a therapeutic fusion DNA vaccine. The potential of plants to manufacture engineered compounds from small to complex protein molecules for pharmaceutical purposes allows the expression of HPV antigens, and possibly also the regulation of immune functions, to develop very specific therapies to reinforce available nonspecific therapies and preventive vaccination in developed countries.…”

Tomatoes: An Extensive Review of the Associated Health Impacts of Tomatoes and Factors That Can Affect Their Cultivation

“…As one of the most popular world crops, the tomato has also been considered as an edible vaccine for a wide variety of diseases, including malaria, coronavirus (COVID-19), human papillomavirus infections, human immunodeficiency virus infections, shigellosis, cholera, anthrax, and hepatitis B [ 97 , 335 , 336 , 337 , 338 , 339 ]. The main objectives of edible vaccines are to democratize preventive vaccination, especially in developing countries, and to better control potential outbreaks such as coronavirus disease.…”

Combating Human Viral Diseases: Will Plant-Based Vaccines Be the Answer?

“…Thus, the use of viral rdrp structural elements as well as the associated regulatory genes which act as suppressors of RNA silencing enabled a several-fold enhancement of production of the HPV antigens. SAPKQ, a nontoxic form of the saporin protein obtained from Saponaria officinalis was fused to the HPV16 E7 protein followed by expression of this candidate vaccine in hairy root cultures of tomato plants using a recombinant plant expression vector [ 136 ]. When mice were immunized with this vaccine formulation, it demonstrated a strong immune response against tumors thus showing anticancer activity.…”