There are good and bad bacteria, but are there any good viruses? And what would happen if all viruses disappeared?
Ron Dippold
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San Diego, California, US
There are technically no 鈥済ood鈥� or 鈥渂ad鈥� viruses or bacteria 鈥� they are completely amoral and selfishly work towards reproducing. Like giant corporations, every bacterium (such as E. coli) or virus (such as SARS-CoV-2) would completely engulf Earth if it could, with zero concern for harm done. Because we are also selfish, we just categorise them as 鈥渂ad鈥� to mean 鈥渕ostly harmful to us鈥�, 鈥済ood鈥� for 鈥渕ostly helpful to us鈥� or 鈥渘eutral鈥�.
There are many viruses that are harmful to us, like most variations of herpes, but there are indeed Many of those are known as bacteriophages, which specifically target bacteria, including those that are bad for us. Most of us have a resident gut virus called crAssphage, which doesn鈥檛 appear to cause any diseases, but seems to keep a common group of bacteria 鈥� Bacteroides 鈥� under control. Not because it is trying to help us (viruses are effectively robots), but because it has specifically evolved to target these bacteria and our guts have a lot of them. However, crAssphage are helpful to us, so they are 鈥済ood鈥�.
One type of herpes seems to fight listeria food poisoning, and the cowpox virus was used to make people immune to smallpox
One version of herpes seems to fight food poisoning caused by listeria bacteria. The cowpox virus was used to make people immune to smallpox. Indeed, there is quite a bit of work on the use of viruses to kill antibiotic resistant bacteria and on the use of We would certainly consider those good.
There is much evidence that, in the past, certain viruses actually became integrated into certain cells in our bodies. The gene in human brain cells is vital for learning and can behave in a way usually seen in viruses, moving its genetic material from cell to cell, suggesting it came from a virus at some point. There is also evidence that viruses have helped certain bacteria by transferring helpful genes to them. Viruses don鈥檛 hate or love, they just reproduce, and with vast numbers of them messing with the DNA of so many cells (bacterial ones or ours), improbable things happen, some of which might turn out to be evolutionarily beneficial.
As for what would happen if all viruses suddenly disappeared, most complex life on Earth would die very soon. Consider your own body. If you are of average size, you contain an estimated of your 鈥渙wn鈥� cells, plus 38 trillion resident bacteria and Yes, more bacterial cells than 鈥測ou鈥� cells, and 10 times more viruses! What you consider 鈥測our鈥� body is, in fact, home to many selfish organisms. The key is that you cells and guest cells establish an uneasy symbiosis or at least tolerate each other.
You get sick when things get out of kilter, like the SARS-CoV-2 virus gets in or your immune system weakens and E. coli runs rampant. As mentioned, those 380 trillion viruses are mostly there to prey on the 38 trillion bacteria.
With the viruses completely gone, the bacteria would completely overwhelm our immune systems and you would have dozens of fatal or crippling illnesses at once. Certainly, you wouldn鈥檛 be able to digest food.
This would also be the case in other animals and in plants. And if all viruses were gone, bacteria in waterways and oceans could multiply explosively. In the end, there would still be some single-celled life left, and maybe even some multicellular forms (tardigrades?), but life as we know it, which has evolved with viruses for 4 billion years, would be over.
Alex McDowell
London, UK
Bacteriophages are viruses that prey on bacteria. They can infect pathogenic bacteria in the body naturally or can be introduced artificially 鈥� a use that may have to grow due to the increasing problem of antibiotic resistance.
In nature, viruses can insert genes into cells they infect and thus assist evolution. This ability is also useful in gene therapy, where modified viruses are used to get therapeutic genetic material into people, for example to treat cystic fibrosis.
The virus that causes myxomatosis has been used to control rabbit populations 鈥� you could argue it is a 鈥済ood鈥� virus.
Many diseases would be eradicated if all viruses vanished, but, according to the hygiene hypothesis, lack of exposure to germs can lead to allergies and autoimmune diseases.
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