Tobacco’s renaissance

Although the sphere of political debate is usually filled with passionate disagreement, there are a few subjects most politicians seem to agree on. You know the ones I mean: crime is bad, children and families are good, and of course, tobacco is the devil.

The tobacco industry largely deserves its public condemnation, but with the recent development of new uses for the oft-maligned tobacco plant, our politicians may be deprived of one of their favourite whipping boys.

Tobacco plants are now being used by a Canadian biotech firm to produce vaccines to influenza faster than conventional production methods allow. There is also a renewed research effort looking into the potential use of tobacco extracts as a natural source pesticide. Together these advancements constitute what we may call a renaissance for the tobacco plant.

Let’s begin by reviewing the basics. Vaccines are used to prep your immune system for a response to some infectious organism, such as a virus or bacterium. A vaccine is often made of some component of the real organism, or possibly a dead or attenuated version of the whole thing. The initial exposure to a vaccine form of the pathogen allows your body to produce large populations of memory cells which remain in your body and are ready to target the real infectious organism when you next encounter it. This way the secondary exposure to the organism will be much larger and faster than if you had not been immunized; thus you are immune.

Currently, vaccines for viruses such as influenza (“the flu”) are produced by allowing the virus to reproduce in primary cells such as those found in chicken eggs. Vaccines for bacteria may simply involve growing bacterial culture. Alternatively, if only a component of the virus particle or bacteria (a toxin, for example) is used in the vaccine, then it may be produced by recombining the target gene with the genome of an easily cultured bacteria or yeast, which will then produce the target protein. These methods of vaccine production are effective, but in an age where the threat of global pandemic requires a quick response, scientists are constantly searching for faster means of large-scale production. This is where tobacco comes in.

Medicago Inc., a Quebec-based firm, has just signed a US$21 million contract with the U.S. Department of Defense to demonstrate its large scale production of plant expressed virus-like particle (VLP) vaccines. Medicago will construct a 8,362 square meter state-of-the-art facility in North Carolina to demonstrate its ability to produce 10 million influenza vaccines a month. The manufacturing process is plant-based and draws on centuries of tobacco growing expertise to make the entire process extremely quick and cost efficient.

The production process begins with sequencing the genome of the virus to be immunized against (usually influenza), then the target gene is synthesized from this sequence. This genetic material is then introduced into the plant via vacuum infiltration, a process where the leaves are immersed in a solution of the genetic material while a vacuum is created above the solution; air leaves the intercellular spaces within the plant, which results in the genetic material being taken up. While some of the details of the process are proprietary, it is sufficient to say that the plant cells soon begin producing proteins and assembling the enveloped VLPs. After a few days of incubation, the plants are then harvested and the VLPs are extracted and purified to obtain clinical grade material.

The main advantage of this plant-based method is its incredible speed. Vaccine production can be initiated in less than three weeks from the identification of the sequence of an influenza strain. When compared to the six months it takes for traditional egg-based methods to produce a vaccine, this is astoundingly fast.
Another advantage is the potential to scale up production rapidly in response to a pandemic. As for the vaccine itself, it has shown strong immune system stimulation and immunologic memory; it also provides cross-protection against different flu strains in addition to the target strain. These significant advantages over traditional methods make the future of plant-based vaccines look bright.

While the tobacco plant may be used to save lives, it can also take lives, specifically the lives of a number of agricultural pests. For centuries people have known that tobacco, when added to water, is an effective pesticide. This effect was primarily attributed to its nicotine content, which can be lethal at correct doses. The advent of synthetic pesticides largely eclipsed this natural pesticide, but new research is giving it a second look.

Cedric Briens of the University of Western Ontario and colleagues at Agriculture Canada recently tested oil extracted from the leaves of tobacco plants to observe its effectiveness as a pesticide. The oil was tested against 11 species of fungus, four different bacterial pathogens and the larvae of Colorado beetles (a potato pest). Their results showed that one species of fungus and two bacteria were affected, while all the beetle larva were killed. It was assumed that these effects, especially the insecticidal ones, were due to the nicotine, but when the researchers removed the nicotine from the oil, they found that it was just as effective against fungi and bacteria. This suggests some new and effective chemicals may be at play, which science has not exploited yet. Further research is needed, but this could represent an important new use for tobacco.

It seems that with new agricultural and lifesaving applications on the horizon, the oft-maligned tobacco plant may be undergoing a renaissance. And if tobacco can turn itself around, then maybe nothing is beyond redemption.