Tobacco cure for ‘cruise ship virus’?

Anyone who regularly travels by plane or ship will probably have fallen victim to norovirus and its unpleasant symptoms of diarrhoea and vomiting. It is sometimes referred to as the “cruise ship virus”, as it has occurred with frightening regularity there, but this microbe can spread like wildfire through any place where people gather such as offices, schools and military bases.

Because of the large numbers of cases, a search has been on for a vaccine and this new certainly is unique in its origin as it was “manufactured” in a tobacco plant using an engineered plant virus. Science has always turned to nature when seeking cures – not always with the best results – but it has been effective in many cases. A study of the top 150 proprietary drugs used in the USA in 1993 found that 57% of all prescriptions contained at least one major active compound derived from plants and we would not have aspirin without white willow bark, or digoxin without digitalis, and many more examples.

Researchers are particularly turning to plants in the battle against fast spreading infectious diseases like norovirus, swine flu, and bird flu. They are doing so because plant biotechnology makes available more efficient and inexpensive ways to bring vaccines quickly to the public and this is especially critical in times when viruses mutate into unpredictable new strains as they are doing more and more today.

It is less expensive than developing conventional vaccines because purification from plant extracts is simpler as there are no infectious agents to clean up. There are no viruses in plants which can infect humans, so you don’t have to worry about viral removal.

Noroviruses are always mutating, making it difficult to produce an effective vaccine in the time scale required. The costs involved in this are huge so it is a great development to be able to use plant biotechnology to create a cheaper, quicker vaccine that is uniquely suited to combat mutating viruses like norovirus and the flu. Plant-based vaccines can be produced and put into clinical tests within eight to 10 weeks and for commercial use that means a fast turnaround of two to four months.

And where does tobacco come in? Well the scientists involved re-engineered plant viruses to produce high levels of specially designed “virus-like” nanoparticles in tobacco plants. These particles are the same size as the norovirus, but they consist only of the outer surface protein — that is the portion of the virus recognized by the human immune system. The particles contain none of the infectious material of the original virus, but they stimulate a robust immune response to fight off an actual infection.

So a good use for tobacco plants, and good news for tobacco farmers who must have seen a serious downturn in profits in the last few years. After successful experiments, a nasal delivery system for the virus-like particles is being developed and will start clinical trials in late 2009.