Viruses: What are they and why are they so hard to eradicate?
We often lump bacteria and viruses together under generic terms like germs or bugs. In reality, they are fundamentally different organisms. Bacteria probably have more in common with bees or monkeys than they do with viruses.
A bacteria is a single-cell organism, a living entity in its own right. Bacteria like to find a cosy environment in which to reproduce, this cosy home-from-home can often be humans. As human landlords we find that most bacteria are harmless and often beneficial tenants, only a small proportion cause us enough trouble to want to evict them.
Viruses are not living entities in their own right. They are a package of genes (made of the same material as our genes) all wrapped up in a protective coat of proteins. Viruses cannot replicate or reproduce on their own, they are like home-invaders that gain entry to living cells and hijack them. They use their host cell’s machinery to replicate and make billions of copies of themselves.
Why are viruses so hard to kill?
Viruses have had millions of years evolving to make themselves hardy and difficult to destroy. As humans we have evolved an incredibly complex and efficient immune system which is primed to detect and destroy viruses, this happens on a daily basis. Inside our bodies, viruses evade detection by disguising themselves with ‘human coats’ – they are camouflaged with very similar proteins and sugars as human cells – they essentially hide in plain sight.
Outside the body viruses are difficult to eradicate for different reasons. They cannot replicate or do anything outside a host organism, they just lie dormant waiting for the next opportunity to invade. Their continued success depends upon their ability to survive as long as possible outside the host cells without food, light, or warmth.
Viruses mutate quickly because that strategy has served them well over millions of years. Mutations are a natural phenomenon in all living systems, viruses multiply faster so the rate of mutations is higher. Mutations impart an increased diversity and variation within a virus population, this large variation is their key weapon in the arms race to outsmart their potential hosts defences. By creating a population of spies with subtly different disguises (new strains), they increase the chances that one will sneak past the immune system inspectors.
Viruses and bacteria do share some similarities such as their vulnerability to soap, alcohol, and strong UV light. Soap and alcohol alter the structure of proteins that form the protective coating of viruses and the cell walls of bacteria. This causes them to become non-functional and incapable of invading new hosts.