Viruses: tales of the unexpected

  • Post Category:Feature
Semper augustus tulip By Unknown artist - Norton Simon Museum, Public Domain,

For something so small it’s amazing how a virus has transformed our world so quickly and so completely. Who would have thought that we had the ability to put wars and terrorism on hold, solve some of the most pressing pollution problems in the biggest cities, reduce our global carbon footprint, and dramatically shift the traditional politics of a major UK party? All in a matter of weeks!

But the darker side of this particular virus – Covid-19 – means that the current pandemic has also had a devastating effect on people and families at a personal level. We all feel for those who have suffered or lost as a result of the disease, and salute the brave and dedicated staff of the NHS and all the other key workers who are keeping things going for the rest of us.

It’s an old, old story…

This might seem like a new situation, but viruses have been about for a very long time – probably since the dawn of evolution, and just occasionally they rise up and remind us they are there. Pretty much every living thing is a host to many different viruses. Put simply, a virus is just a handful of genes wrapped up in a ball of protein only millionths of a millimetre in diameter. Outside of a living organism they are inert and left for too long without a host they simply perish. They exist in man, all other animals, plants and bacteria and they need to be inside to multiply. Some are probably essential to us such as the bacterial viruses in our gut which keep our microbiome in shape and help our immune system.

We have all suffered viral diseases of one type or another from colds and flu to measles and chickenpox. Some human viral diseases are very nasty, but thankfully rare, such as Ebola. But, ironically, milder viral diseases are likely better at survival than more severe ones. Viruses also affect plants and can cause devastating crop losses with consequences for people’s lives and living around the world. We have evolved an uneasy relationship with our viruses but their presence has probably kept our natural defences in better shape – at least from an evolutionary standpoint.

Coronavirus Covid-19. CDC/ Alissa Eckert, MS; Dan Higgins, MAM / Public domain

Genies jumping out of the bottle

Problems are more likely to arise when viruses which normally affect animals jump into man, like the coronavirus, Covid-19. This happens less often in nature but is more likely when large numbers of our food animals interact with wild species. The human immune system has no experience of the viruses crossing from wild animal species and we are laid bare to the consequences. Our only solid defence against such a situation is vaccination, whereby a non-infectious part of the virus is inoculated into us to stimulate our immune systems to fight off a subsequent infection. But vaccine development is not always straightforward and it takes time to make a new vaccine, test it thoroughly for effectiveness and side-effects, and then bulk it up to billions of doses. And, the length of vaccine effectiveness varies a lot. This is where we are now – in a period of unsettling uncertainty.

Viruses, the upside?

But, you have probably heard too much about the bad side of viruses from the daily – hourly – news. In fact, viruses have some unexpected features and uses too.

Although it was not known at the time, a virus caused a huge stir in the Dutch bulb industry in the seventeenth century where fortunes were made – and subsequently lost. A tulip ‘sport’ arose in cultivation producing a dramatic and beautiful flower in which the colour of the bloom fragmented into stiped patterns. The bulbs producing these ‘broken’ flowers attained enormous prices until there was eventually a run and then the inevitable crash in prices. This was the period of ‘tulip mania’.

Virus-infected tulips in a still life painting. By Hans Bollongier - www.rijksmuseum.nl : Home : Info : Pic, Public Domain,

The rarity and uniqueness of the bulb and their blooms and the difficulty in predictably propagating them added to their desirability. In the twentieth century, it was discovered that the effect on the flowers was produced by an infecting virus, called tulip breaking virus, a member of the potato virus Y family of viruses. But, for a while this virus supported the Dutch economy and the livelihoods of many a Dutch Master who used the rare tulips as subjects for their still life paintings.

Search and research

Viruses have been studied extensively by scientists since their discovery as unique genetic entities in the first half of the twentieth century. Viruses are not only important disease-causing agents, they are also relatively simple model systems for investigating the more genetically complex systems of animals, plants and bacteria. Some of the most important basic questions in biology and medicine about what genes are and how they work have been answered using viruses as research tools. Viruses that are modified in the laboratory so that their disease-causing properties are removed are now used in gene therapies to reverse human genetic abnormalities by carrying repaired genes into patients.

Because some groups of viruses share similarities from widely differing origins, discoveries made in say, plant viruses, can be applied in a medical setting. An example is the discovery of a novel antiviral defence mechanism found in plants – called ‘gene silencing’ – now used in a wide range of research areas and in treating human diseases including cancer.

Plants are good subjects for researchers to study viruses. One method that is used to understand viruses is to modify the virus – in the lab – to carry an extra gene to enable researchers to work out where a virus goes and what it does during the infection process. The photo below shows what happens to a plant virus that has been modified to carry an extra gene taken from a jellyfish that makes a protein that glows in ultraviolet light allowing researchers to track the virus.

Tracking a virus infection in a plant. The virus was modified (by a resident of Tuttington) by addition of a jellyfish gene which glows in UV light. The virus moves through the veins of the leaf (left) and in a cross section of the leaf stalk (right) the tell-tale glow of the virus can be seen in the food -conducting and not in the water-conducting channels

Another example is where plant viruses carrying extra genes are being used to develop a possible vaccine against coronaviruses. The advantages of using plants to develop human and animal vaccines is that very large amounts of vaccine can potentially be produced relatively quickly by harvesting plants infected with the modified virus and then extracting the vaccine.

This brings us back to our current virus problem and the realisation that many different research approaches will likely be needed before we get the upper hand on Covid-19 – which we will, eventually…