Influenza: making vaccines in plants

The Ministère de la Santé et des Services Sociaux du Québec recommends annual vaccination against influenza.

Sometimes a second vaccination is required when there is a risk of pandemic, as happened in 2009 with the H1N1 virus. As pandemics are generally hard to predict, it is important to be able to produce effective, safe vaccines quickly. In collaboration with the Québec company Medicago, McGill University professor Brian Ward and his team are working on developing new influenza vaccines that meet these requirements.

The research team produced 10 million doses in less than four weeks.

Vaccines are usually produced in animal cells or eggs. These new vaccines, on the other hand, are grown in a greenhouse with the use of a close relative of the tobacco plant: Nicotiana benthiana. The main advantage of this technique is that there is no period of adaptation to the host cells, which speeds up production of the vaccine. In addition, they cost less to manufacture, require less infrastructure, and are safer. But above all, these vaccines are made with wild viral proteins rather than viruses that that have been genetically adapted for growth in eggs.

In contrast to traditional vaccines, which are produced from live viruses, the vaccines developed by Medicago and Brian Ward are made from a virus-like particle (VLP), consisting of the shell of the virus, or viral envelope, which contains no viral genetic material. Once injected, the virus-like particle looks like the original virus. The human immune system is unable to tell the difference between the two, and creates antibodies to eliminate the infection.

The advantages of plant-based vaccines include the fact that they are extremely pure: they contain very little trace of host cells (the plant, in this case) compared with vaccines that are produced in eggs. This could reduce, or even eliminate, side effects such as allergic reactions.

Four clinical trials have been carried out to test the efficacy of the new vaccines. The results are very promising: the vaccines appear to be at least as effective as traditional vaccines. They generate a stronger immune response in humans, comparable to that observed in the case of an actual influenza infection.

This technique for large-scale vaccine production proved its worth in 2012 with the manufacture of a pH1N1 vaccine in a North Carolina vaccine facility. The research team produced 10 million doses in less than four weeks. A facility like this could produce enough doses for the entire Canadian population in less time than it takes to generate the first doses of a traditional vaccine.

The project has garnered interest and support, not only from Canadian Institutes of Health Research institutes, but also from the Defense Advanced Research Projects Agency (DARPA) in the USA. For now, a small production facility has begun operations in Québec. The next step: the construction of a large-scale production facility to respond to the next influenza pandemic.