Virus-based pharmaceutical production in plants: an opportunity to reduce health problems in Africa

Abstract

Background: Developing African countries face health problems that they struggle to solve. The major causes of this situation are high therapeutic and logistical costs. Plant-made therapeutics are easy to produce due to the lack of the safety considerations associated with traditional fermenter-based expression platforms, such as mammalian cells. Plant biosystems are easy to scale up and inexpensive, and they do not require refrigeration or a sophisticated medical infrastructure. These advantages provide an opportunity for plant-made pharmaceuticals to counteract diseases for which medicines were previously inaccessible to people in countries with few resources.

Main body: The techniques needed for plant-based therapeutic production are currently available. Viral expression vectors based on plant viruses have greatly enhanced plant-made therapeutic production and have been exploited to produce a variety of proteins of industrial, pharmaceutical and agribusiness interest. Some neglected tropical diseases occurring exclusively in the developing world have found solutions through plant bioreactor technology. Plant viral expression vectors have been reported in the production of therapeutics against these diseases occurring exclusively in the third world, and some virus-derived antigens produced in plants exhibit appropriate antigenicity and immunogenicity. However, all advances in the use of plants as bioreactors have been made by companies in Europe and America. The developing world is still far from acquiring this technology, although plant viral expression vectors may provide crucial help to overcome neglected diseases.

Conclusion: Today, interest in these tools is rising, and viral amplicons made in and for Africa are in progress. This review describes the biotechnological advances in the field of plant bioreactors, highlights factors restricting access to this technology by those who need it most and proposes a solution to overcome these limitations.

Keywords: Developing African countries; Neglected diseases; Plant viral expression vectors; Plant-made therapeutics; Recombinant proteins.

Fig. 1

Comparison of the efficiency of protein production systems. Cost, speed, posttranslational modifications and safety are considered (adapted from [19]). Plant production systems noted in green are compared to transgenic animal (noted in red), mammalian cell (noted in blue), insect (noted in purple), yeast (noted in orange) and bacterial (noted in gray) production systems

Fig. 2

Schematic representation of gene of interest overexpression through a- transient expression system using viral RNA silencing suppressor and b- engineered amplicon vectors based on viruses. Genes encoding proteins of interest are represented as pink lines and the viral genome is represented as blue lines. Promoters driving constructs are represented as black arrows

Fig. 3

Simplified diagram of a plant viral based expression vector. TMV virus has been taken here as a model virus for viral vector construction illustrations. The figure have been adapted from Liu et al. [56]. a- Viral expression vector constructions based on the full virus strategy, upper part: the gene of interest is under the control of TMV CP promoter. Lower part: the gene of interest expression is governed by a new promoter. b- Vector construction based on the deconstructed virus strategy. ORFs are labeled in each box. MP: movement protein, CP: coat protein, GOI: gene of interest, arrow: promoter

Fig. 4

Schematic representation of the steps required for the development of plant-virus-based biotechnological tools in developing countries. For each step represented by the blue arrow, the prerequisites and benefits associated with the implementation in developing countries are shown in red and green, respectively