Plant-made Biopharmaceuticals Research Articles

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

Molecular pharming or the technology of application of plants and plant cell culture to manufacture high-value recombinant proteins has progressed a long way over the last three decades. Whether generated in transgenic plants by stable expression or in plant virus-based transient expression systems, biopharmaceuticals have been produced to combat several human viral diseases that have impacted the world in pandemic proportions. Plants have been variously employed in expressing a host of viral antigens as well as monoclonal antibodies. Many of these biopharmaceuticals have shown great promise in animal models and several of them have performed successfully in clinical trials. The current review elaborates the strategies and successes achieved in generating plant-derived vaccines to target several virus-induced health concerns including highly communicable infectious viral diseases. Importantly, plant-made biopharmaceuticals against hepatitis B virus (HBV), hepatitis C virus (HCV), the cancer-causing virus human papillomavirus (HPV), human immunodeficiency virus (HIV), influenza virus, zika virus, and the emerging respiratory virus, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have been discussed. The use of plant virus-derived nanoparticles (VNPs) and virus-like particles (VLPs) in generating plant-based vaccines are extensively addressed. The review closes with a critical look at the caveats of plant-based molecular pharming and future prospects towards further advancements in this technology. The use of biopharmed viral vaccines in human medicine and as part of emergency response vaccines and therapeutics in humans looks promising for the near future.

Efficacy of the corn smut-made CTB oral vaccine on mucosal immune parameters in Pacific red snapper (Lutjanus peru)

Plant-made biopharmaceuticals are biotechnological valuable tools in aquaculture. Herein, the immunogenic potential of an oral corn smut (‘huitlacoche’)-made antigen (CS) was assessed in Pacific red snapper. The B subunit of the cholera toxin (CTB) was used as an immunostimulant antigen model due to its well-proven mucosal immunostimulatory activity. Test fish received corn smut-based CTB (CS-CTB) or wild-type (CS-WT) as control on day 1 and 7. Changes in humoral and cellular innate immune parameters were evaluated at 7 and 14 dpi (days post-first immunostimulation). Interestingly, total IgM and anti-CTB IgM levels in skin mucus increased in all the assessed time points in the group treated with CS-CTB. Peroxidase activity significantly increased in both serum and skin mucus from immunostimulated fish. The SOD and CAT activities were significantly increased in mucus from stimulated fish with the CS-CTB. The test fish that received CS-CTB showed enhanced phagocytic ability and radical production in head-kidney leukocytes compared with the control group. In addition, oral administration of CS-WT significantly increased the expression levels of pro-inflammatory cytokines. These findings support the use of the corn smut as a biofactory and oral delivery vehicle of novel immunostimulants, such as CTB, for fish aquaculture.

Plant Virus Expression Vectors: A Powerhouse for Global Health.

Plant-made biopharmaceuticals have long been considered a promising technology for providing inexpensive and efficacious medicines for developing countries, as well as for combating pandemic infectious diseases and for use in personalized medicine. Plant virus expression vectors produce high levels of pharmaceutical proteins within a very short time period. Recently, plant viruses have been employed as nanoparticles for novel forms of cancer treatment. This review provides a glimpse into the development of plant virus expression systems both for pharmaceutical production as well as for immunotherapy.

Pneumatic hydrodynamics influence transplastomic protein yields and biological responses during in vitro shoot regeneration of Nicotiana tabacum callus: Implications for bioprocess routes to plant-made biopharmaceuticals

Transplastomic plants are capable of high-yield production of recombinant biopharmaceutical proteins. Plant tissue culture combines advantages of agricultural cultivation with the bioprocess consistency associated with suspension culture. Overexpression of recombinant proteins through regeneration of transplastomic Nicotiana tabacum shoots from callus tissue in RITA® temporary immersion bioreactors has been previously demonstrated. In this study we investigated the hydrodynamics of periodic pneumatic suspension of liquid medium during temporary immersion culture (4min aeration every 8h), and the impact on biological responses and transplastomic expression of fragment C of tetanus toxin (TetC). Biomass was grown under a range of aeration rates for 3, 20 and 40-day durations. Growth, mitochondrial activity (a viability indicator) and TetC protein yields were correlated against the hydrodynamic parameters, shear rate and energy dissipation rate (perkg of medium). A critical aeration rate of 440mlmin−1 was identified, corresponding to a shear rate of 96.7s−1, pneumatic power input of 8.8mWkg−1 and initial 20-day pneumatic energy dissipation of 127Jkg−1, at which significant reductions in biomass accumulation and mitochondrial activity were observed. There was an exponential decline in TetC yields with increasing aeration rates at 40days, across the entire range of conditions tested. These observations have important implications for the optimisation and scale-up of transplastomic plant tissue culture bioprocesses for biopharmaceutical production.

Current Developments and Future Prospects for Plant-Made Biopharmaceuticals Against Rabies.

Rabies is a prevalent health problem in developing countries. Although vaccines and immunoglobulin treatments are available, their cost and multiple-dose treatments restrict availability. During the last two decades, plants have served as a low-cost platform for biopharmaceuticals production and have been applied to fight against rabies during the last two decades. Herein, I provide a description of the state of the art in the development of plant-made pharmaceuticals against rabies and identify key prospects for the field in terms of novel strategies, immunogen design, and therapeutic antibodies production.

The Potential Impact of Plant-made Biopharmaceuticals for the Improvement of Global Health

The Potential Impact of Plant-made Biopharmaceuticals for the Improvement of Global Health

Plant‐specific glycosylation patterns in the context of therapeutic protein production

While N-glycan synthesis in the endoplasmic reticulum (ER) is relatively well conserved in eukaryotes, N-glycan processing and O-glycan biosynthesis in the Golgi apparatus are kingdom specific and result in different oligosaccharide structures attached to glycoproteins in plants and mammals. With the prospect of using plants as alternative hosts to mammalian cell lines for the production of therapeutic glycoproteins, significant progress has been made towards the humanization of protein N-glycosylation in plant cells. To date, successful efforts in this direction have mainly focused on the targeted expression of therapeutic proteins, the knockout of plant-specific N-glycan-processing genes, and/or the introduction of the enzymatic machinery catalyzing the synthesis, transport and addition of human sugars. By contrast, very little attention has been paid until now to the O-glycosylation status of plant-made therapeutic proteins, which is surprising considering that hundreds of human proteins represent good candidates for Hyp-O glycosylation when produced in a plant expression system. This review describes protein N- and O-linked glycosylation in plants and highlights the limitations and advantages of plant-specific glycosylation on plant-made biopharmaceuticals.

Green Biofactories: Recombinant Protein Production in Plants

Until recently, low accumulation levels have been the major bottleneck for plant-made recombinant protein production. However, several breakthroughs have been described in the past few years allowing for very high accumulation levels, mainly through chloroplast transformation and transient expression, coupled with subcellular targeting and protein fusions. Another important factor influencing our ability to use plants for the production of recombinant proteins is the availability of quick and simple purification strategies. Recent developments using oleosin, zein, ELP and hydrophobin fusion tags have shown promise as efficient and cost-effective methods for non-chromatographic separation. Furthermore, plant glycosylation is a major barrier to the parenteral administration of plant-made biopharmaceuticals because of potential immunogenicity concerns. A major effort has been invested in humanizing plant glycosylation, and several groups have been able to reduce or eliminate immunogenic glycans while introducing mammalian-specific glycans. Finally, biosafety issues and public perception are essential for the acceptance of plants as bioreactors for the production of proteins. Over recent years, it has become clear that food and feed plants carry an inherent risk of contaminating our food supply, and thus much effort has focused on the use of non-food plants. Presently, Nicotiana benthamiana has emerged as the preferred host for transient expression, while tobacco is most frequently used for chloroplast transformation. In this review, we focus on the main issues hindering the economical production of recombinant proteins in plants, describing the current efforts for addressing these limitations, and we include an extensive list of recent patents generated with the intention of solving these limitations.