A fresh approach to a global challenge: plant-based vaccines explained

This week sees the World Vaccine Congress Europe take place, following a sister event in Washington DC, USA, last month.

With the search for a COVID-19 vaccine being a global priority and challenge for the scientific community, this is arguably one of the most important congresses ever.

When BAT, via our subsidiary Kentucky BioProcessing (KBP), announced in April that we were working on a COVID-19 vaccine candidate, using novel tobacco plant technology, it was a surprise to many.  We continue to work hard on this and our influenza candidate vaccine, and we anticipate our COVID-19 candidate vaccine will be in human trials in the coming months.  We hope and are preparing for success, given the urgent need, and also believe plant-based biologics have exciting potential for use in treatment and prevention.  So, we thought it would be helpful to explain a bit more about this technology.

Why vaccines?

Science is at the core of everything we do, as we aim to build A Better Tomorrow by reducing the health impact of our business.  For many years we’ve been looking for alternative uses for tobacco plants and have been working with KBP since 2009 before acquiring the business in 2017. KBP is an expert in plant-based research using pharmaceutical-grade extraction and purification processes.  The company has been investigating ways of potentially creating faster and more efficient methods for developing, growing and extracting biopharmaceuticals. Using tobacco plants as the ‘host’ or a factory to produce the antigen is one possible route to this.

How does it work?

The COVID-19 candidate vaccine in development uses BAT’s proprietary, fast-growing tobacco plant technology. The variety we use for biological production is the Nicotiana benthamiana plant, which we grow indoors in a highly controlled environment. We then clone a portion of the genetic sequence encoding a selected coronavirus antigen – the substance which induces an immune response in the body and the production of antibodies.

This genetic sequence is then inserted into our plants. One of the benefits of using tobacco plants is that it takes just six weeks for the genetic sequence to be permanently inserted into the genome of the plants and just one week of actual growth before you can extract the biopharmaceutical. Once the plants are harvested, the antigen is then purified.

To find out more about KBP and our tobacco plant-based technology, watch our video below:

The advantages of tobacco plant technology

This technology has several potential advantages over conventional vaccine production technology.  These include:

  1. Tobacco is a “model plant”, which is well characterised and understood. Genomes of several varieties have been published.
  2. Tobacco plants are excellent at expressing, assembling, modifying and replicating large and complex biomolecules with high fidelity.
  3. Safety – the plant has no human pathogens that could contaminate any biological molecule or formulation.
  4. Biopharmaceuticals manufactured inside tobacco plants are stable at room temperature for potentially up to 12 months – unlike conventional vaccines which usually require refrigeration during transport and storage.  This could be a great advantage in countries where refrigerated supply chains are not available.
  5. N. Benthamiana is highly tractable – it is relatively quick and easy to get these plants to incorporate new genetic material in a stable way (around 6 weeks). This could enable us to rapidly respond to a new public health crisis or seasonal strain. Coupled with the speed of production of the biopharmaceutical once the new plants are created, the plant can function as a “bioreactor” to produce high yields of biopharmaceuticals.

These advantages mean that this plant-based technology could be of particular use for seasonal influenza vaccine development, where part of the challenge for public health authorities lies in predicting in advance which strains are going to come to their country.  Thanks to the speed at which these new plants can be created, public health authorities could choose the strains up to six months closer to flu season, thereby significantly increasing the chances of accurate identification of the correct strains that will dominate that year. This could potentially revolutionise how public health authorities approach seasonal flu.

In summary, while still at an early stage, plant-based biologics have enormous potential and warrant close attention.  This is a novel platform that combines high efficiency with unique properties that could have significant advantages over conventional methods.  With the benefits of vaccines being well understood, and pandemics and epidemics having greater impact than ever, the role of plant-based biologics and their potential has never been more important.

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