Plant based vaccines have positive implications for developing countries where the infrastructure for vaccine production is limited.
Cape Town - Scientists from the University of Cape Town, who spent two decades studying plant-made vaccines before shifting their focus to Covid-19 when the pandemic struck, have reported a successful, near-full length SARS-CoV-2 vaccine spike in plants.
UCT postdoctoral scientist at the Institute of Infectious Diseases and Molecular Medicine, Emmanuel Margolin, said the production of proteins in plants with pharmaceutical value has been pursued for several decades following the realisation that a plant pathogen, Agrobacterium tumefaciens, could be engineered to introduce foreign DNA into plant cells.
“This bacterium naturally infects plants leading to the formation of crown gall tumours following the transfer of its genetic material into the host plant. Scientists have disarmed the bacteria and exploited it as a vehicle to deliver the genetic code for pharmaceutically relevant proteins, such as vaccines.”
“This is achieved by infiltrating the bacteria containing the DNA of interest into plants under a vacuum which turns the plant cells into factories to produce the protein of interest. The species Nicotiana benthamiana is most commonly used for this purpose as it is highly susceptible to A tumefaciens and grows rapidly.”
“In our group, the Biopharming Research Unit, we use this system to produce proteins from viruses which can then be injected as vaccines. We are pursuing plant-based production over other approaches due to the less stringent infrastructure requirements in the system and the lower production costs. This is highly desirable in developing countries where the infrastructure for vaccine production is limited.
“The basis for our technology is to also introduce human folding proteins into the plants to support the production of complex proteins which could not otherwise be produced in the system due to differences in the host machinery. We have a suite of patented approaches which we have applied to producing the SARS-CoV-2 spike glycoprotein,” said Margolin.
With the vaccine rollout programme already in full swing, Margolin said the main obstacle to further development of these forms of vaccines was a lack of infrastructure for manufacturing on the continent.
“There are currently no facilities capable of manufacturing on scale or under the necessary conditions to progress to human testing. While production costs and the cost to establish a facility is lower for plant-based manufacturing this still requires a considerable capital investment.”
“Another major obstacle is the lack of funding support for further development. Although we had shown proof-of-concept that we could produce the vaccine in plants early on in the pandemic, we did not have adequate funding support to progress with further development. Unfortunately, this has resulted in this project being run in the background rather than as a dedicated project of its own. This has been further exacerbated by Covid related funding cuts to key initiatives,” said Margolin.
Vaccinologist at Vaccines for Africa, Dr Benjamin Kagina said that although the plant based vaccine could be seen beneficial from a financial and safety point of view, a lot still needs to be done in order to stand head to head with the rise of the new technological method of how vaccines are manufactured.
“With scientists exploring different ways of making vaccines, plant based vaccine development is purely born from the need to understand how the human immune system works. However with the competing era of technology, I think that the development is still growing and a lot still needs to be taken into consideration in order to stand against what is already out there.”
“Plant - based vaccines, I think needs to be relooked at so that the regulators who are the vita; in vaccine development can see the true potential this development has, given all the data is revised and is affected to the standard practice because at the end of the day, nothing is wrong with having to go natural way of acquiring vaccine, it just needs to be precise and thorough,” said Kagina.
The UCT study takes advantage of recent advancements in the Biopharming Research Unit (BRU) to generate interacting viral surface glycoproteins in plants, by supplying components of the human intracellular folding machinery. This technique is part of a new research effort aimed at developing innovative methods for generating vaccines in plants against arising viruses.
Weekend Argus