Tobacco to the rescue
Tobacco plants and cuttings raised for Covid-19 vaccine research.
The tobacco plant may receive a lot of bad rap, but few of the staunch critics ever acknowledge that it also has great potential to actually save lives.
By Thomas Schmid
Using a plant to “grow” a specific therapeutic drug or even vaccine for human use sounds like a yarn straight out of an Arthur C. Clarke science fiction novel. And no, we are not referring to actual plant parts or extracts of phytochemicals naturally occurring in plants that are then manufactured into herbal teas, tinctures, ointments, or pills. Rather, we are talking about the propagation of substances that are not naturally present in plants in the first place – artificially introduced “foreign substances,” so to speak.
Yet this is exactly what is being achieved in a process known as “biopharming”, a technology that over the past decade or so has been perfected to a degree where drugs can indeed be “grown” in plants in a controlled manner and in commercial quantities. The process is complex, of course, involving – among other crucial steps – the genetic manipulation of the “host” plant. Yet it works. But for a broad variety of reasons and depending on the type of drug, not all plant species are suitable for biopharming.
Enter tobacco, that vilest and most demonic of plants, which – if the anti-tobacco lobby had its short-sighted way – would’ve been wiped off the face of the planet long ago. Luckily, it wasn’t, and in fact, it apparently is coming in extremely helpful in the face of the current Covid-19 pandemic.
None other than British American Tobacco (BAT) and its US biotech subsidiary Kentucky BioProcessing (KBP) are feverishly working on a SARS-CoV-2 vaccine that is “grown” in bio-engineered tobacco plants.*.
Pre-clinical testing has already commenced and if these tests go well, “between 1 and 3 million doses of the vaccine could be manufactured per week, beginning in June,” BAT told the UK newspaper, The Guardian. BAT said in the report it had cloned a portion of the genetic sequence of SARS-CoV-2 (the virus that causes the Covid-19 disease) and developed a potential antigen. That antigen is then inserted into tobacco plants to reproduce in the cells. After harvesting the plants, the accumulated antigen is extracted and purified, forming the basis of a vaccine that could potentially put an end to the Covid-19 scare, and it is precisely that very antigen-derived vaccine which is currently undergoing pre-trial testing. Let’s keep our fingers crossed.
But why tobacco? Couldn’t just any other random plant species – say daffodils, if just to appease the lobbyists – serve as an antigen “incubator”? Not so, according to KBP, which was quoted in the Guardian article as saying that using tobacco was “potentially safer [than conventional vaccine technologies], given that tobacco plants cannot host pathogens which cause human disease.” Another aspect is that tobacco by nature matures very fast. And that’s important to ensure that vaccine components can be harvested quickly and in sufficient quantities. The bio-engineered plants utilized by KBP have of course an even faster growth rate, significantly shortening the time span from seeding until harvesting to only 40 days, whereas the antigen is introduced when the plants are about 3 weeks old. While tobacco certainly is not the only plant species that can (and is) utilized for biopharming in general, it is in this case without doubt among the best shots humankind presently has at obtaining an effective vaccine against Covid-19 as soon as possible.
Interestingly, this is also not the first time that tobacco has been deployed in developing a treatment for a devastating viral disease. Prior to BAT’s 2014 takeover of KBP, the biotech firm had already worked on a treatment for Ebola. Again, antigens were injected into tobacco plants. Not daffodils. The harvest – after undergoing further processing steps – was then added as a component to ZMapp, an experimental anti-viral drug that was used in several African countries where Ebola outbreaks occurred. Although ZMapp never was conclusively proven to have substantial efficacy, claims emerged that it did in fact lower the mortality rate among Ebola victims and that people even had been cured with it. ZMapp today has been largely phased out as an Ebola treatment and also is no longer recommended by the WHO, but the drug’s development nevertheless established tobacco biopharming as an efficient method for antigen or antibody propagation.
Canadian biotech company Medicago likewise has successfully used tobacco plants to develop a seasonal influenza vaccine. Although this “quadrivalent VLP influenza vaccine” has so far not been approved for human use in any country and still is under clinical investigation, the company website states that “research and trials to date indicate a demonstrated safety profile in adults, including those over the age of 65 years.” The vaccine candidate is expected to stimulate a balanced antibody and cellular immune response and efficacy against various influenza strains in the human body. During a television interview broadcast by PBS News Hour in November 2015, Medicago’s vice president of operations, Dr. Michael Schunk, said the tobacco plants at the company’s growing facility were able to produce the vaccine over the course of just one week. “[The process is] very quick, very efficient, very adaptable,” Dr. Schunk asserted. The plant technology could respond in about half the time of the traditional flu manufacturing technologies using animal cells (typically chicken eggs). “So that’s what started us into the flu, and we have just continued to grow with that,” he said.
But Dr. Schunk also pointed out that the technology held promise for all kinds of drugs. Developing nations, in particular, could benefit from it, as the cost of building growing facilities to host the plants would be much less than traditional drug factories. “Every country has greenhouses, so every country has the potential to have a facility that can be used to produce vaccines that maybe are more of a concern to that particular country,” he told interviewing journalist Mary Jo Brooks. The journalist concluded her report with the bold prediction that drugs to treat herpes, HIV, MRSA, and other infectious diseases could routinely be biopharmed using tobacco plants in the near future. “Of course, the irony of using a version of [bio-engineered] tobacco to save lives is not lost on anyone,” she remarked. The anti-tobacco lobby must be fuming.
*Tobacco Asia will publish an in-depth article on BAT’s vaccine development in a forthcoming issue.