Fighting viruses is fighting life itself
“We can no more be cured of our viruses than we can be relieved of our brains' frontal lobes: we are our viruses.”
- Lyn Margulis, evolutionary biologist
When the results of the Human Genome Project became known, we learned 80% of our DNA did not come from monkeys, but from viruses. The fact that we are not born in an egg is due to viruses. Can we permanently eradicate viruses if they are so much a part of who we are?
Tirelessly, the thousand-headed virus monster stirs at any time of the day, on any continent. Cold sores, AIDS, ebola, smallpox, rabies, cold, flu, corona. Everywhere the virus monster rears its head hell breaks loose. It is almost impossible to escape a virus, they settle in your body, suck themselves to your cells and use your cell nuclei to spread their own disease-causing genetic material, and thus jump from host to host. You may be disgusted by the thought of viruses colonizing your body. But viruses know us and our cell systems more intimately than we do—they've been studying us for millions of years, while we barely know viruses.
The crushing goodness of the virus
The vast majority of our DNA, 80%, does not come from our ape-like ancestors, but from viruses. Viruses are part of the DNA of every living species, from strawberry plants to E. coli. Countless viruses reside in our bodies, our seas (there they diligently capture CO2), our soil, and even interplanetary space . A overwhelming majority of viruses are not harmful: there are an estimated 10 to the power of 32 (that is and 1 with 32 zeros, more than there are stars in the universe) viruses on Earth and only 1000 are known to cause disease . Unfortunately, COVID-19 is one of them. The other viruses are indispensable for maintaining life on Earth. That 'virus' seems to be synonymous with 'terrible pathogen' is an exaggeration to say the least.
The word virus was once derived from the Latin virus, meaning "slimy poisonous liquid", especially snake venom. In the 17th century it came to the Netherlands to designate pathogenic fluids, and it is only since 1950 that we have used virus as a 'submicroscopic pathogen' (Van Dale).
I propose a new definition: virus is the unmoved mover, first building block of life, catalyst of evolution and protector of all life on Earth and beyond. It is neither good nor bad, it is. And we will have to learn to live with it.
Now what is a virus exactly? A virus is in fact a piece of DNA or RNA covered by proteins. To replicate, viruses control their host's living cells to make the host cells carry out their own genome instructions. They are parasites. They do not have their own metabolism and use energy from the host to do their job.
Due to their dependence on host cells, most scientists do not regard viruses as living, but as a 'biologically active entity'. Taking a closer look at the arguments for the virus being 'non-living', is there really a biological basis for this classification? What is life?
To live is to be born and to die
Something that lives has a beginning and an end: it is born and it dies. A virus makes copies of itself that live on indefinitely. It has no clear 'beginning' or 'end'. However, the lack of a clear beginning and end is not unique to viruses. Some plants can reproduce asexually. Strawberry plants form runners from which new plants grow. These can grow into independent plants, and contain the same DNA as the mother plant. When does the strawberry plant die? If all the offspring have also died? Or does the plant in fact live on immortal? And while the first strawberry plant was once "born" from a strawberry seed, there may have been an ancestor of the virus that was the first—if you go back far enough in time. More on that later.
The inability of viruses to live and reproduce is a second argument for calling viruses non-living. They need the help of their host with everything. Viruses are not unique in this either. The same can be said for many species that are seen as living. Coral, for example, cannot live or grow without the help of parasitic, photosynthesizing microbes: the bacteria provide energy, and the corals provide nutrients to the microbes.
Even of you, reader, I cannot say that you can live independently or reproduce. For this you depend on a microbiome that lives in your body: millions of bacteria that perform essential bodily functions in your body, such as brain development, digestion of food and development of your immune system.
In fact, it is a rather narrow view of 'life' to call a virus non living.
First building block of life
Viruses are very old and were probably one of the first life forms on Earth. Ribozymes and RNA enzymes are considered to be the first replicating units and have virus-like characteristics. Could viruses be the model structures for very first life?
Viruses may have been more complex in those early days, had more functions and a non-parasitic life form. The ancestor may have been "really alive," and later it lost certain traits and evolved into a simpler creature. We often think that evolution is headed in one direction, towards increasingly complex species. The opposite is also true: evolution can move towards increasingly complex forms (in times of great competition or scarcity), but also towards increasingly simple forms (in times of abundance). They are two different strategies and it seems that the virus has chosen the latter.
Viruses colonize cells of animal and plant species and take over the whole mechanism. In rare cases, they infect an organism's sex cells, the proto-egg and sperm cells. With this action, they are, as it were, ingrained in the host's DNA and passed on from generation to generation. They become part of other species. Of us as human beings, for example.
This process is known as endogenization. It is probably responsible for the fact that so much of our DNA and that of all living organisms is of viral origin.
An example of such an 'ingrained' virus (related to the HIV virus) makes it possible that we humans do not lay eggs, but are born alive. This works as follows: viruses have created our immune system (more on this later), and can also partially shut down that immune system. That trick (immune tolerance) means we don't have to lay eggs or carry our offspring in a kind of kangaroo pouch, but can develop mammalian babies in the mother's body until they are born. That's an insane thing to think about! This would never have been possible without viruses.
Our scariest enemy or greatest protector?
If viruses have infected a cell, they would rather have no competition there. Not even their own kind. They defend their host cell from other invaders, do not let them in or destroy them. This protects the host from more pathogens. When viruses have ingrained themselves into our human genome, this mechanism becomes part of our immune system. Viruses therefore defend us, against other viruses, but also against bacteria. All known immune systems are likely designed by viruses. Viruses are part of the microbiome that lives in humans (and every other organism) and is unique from individual to individual. Mothers pass on their microbiome to their children during childbirth, but people who live together or hug on the street also exchange bits of their microbiome.
There is certainly something to be said for reducing harmful viruses and limiting the harmful effects (death and destruction). But with the above knowledge in mind, I conclude that fighting viruses is an unwinnable battle.
Can we permanently 'check' (what does that even mean?) or eradicate viruses, and if we do, how can we be sure we're on the side of the winners? After all, we are all descendants of survivors of viruses, of pandemics of the past, and also reap the benefits of our immune systems tuned to the harmful viruses and bacteria of the earth and our miraculous capacity for viviparous births. And maybe even our complete humanity. Pandemics force species to adapt or become extinct. It turns out that 30% of all protein adaptations since humans and chimpanzees split from each other have been driven by viruses.
In short, viruses trap CO2 in the oceans, prevent us from being born in an egg, stimulate our brain development, food digestion, behavior and emotion, protect against similar viruses and have made us human. Viruses are drivers of evolution, and the process continues to this day.
Fighting viruses is fighting life itself.