What are viruses?

Recently, we have been hearing “viruses” in the news, internet, from our neighbours, colleagues, and from almost everyone around the globe. This so-called “COVID-19” has taken the spotlight for the past four months and has tremendously affected society and businesses around the world. The worst part is, it has effortlessly taken thousands of human lives.

But before we proceed on how these viruses affect us, it is important to understand what viruses are. So let’s start with the basics.

VIRUSES are NOT LIVING ORGANISMS.

Yup, you read it right. Viruses are not living organisms. They are not like us. They cannot reproduce by itself, hence, viruses are considered as non-living. A virus particle is basically an infectious package made up of nucleic acid (either RNA or DNA) and protein. The other important organelles are not present, so they need to find a host to do the job for them. So you might be wondering, “If they can’t reproduce, how come they have infected a lot people?”. Good thought. Well,

“A virus is a small parasite that cannot reproduce by itself. However, once it infects a susceptible cell [host], a virus can direct the cell machinery to produce more viruses.”

Lodish et al. 2000

This means that viruses need a HOST so they can reproduce. The virus is commandeering (hijacking) a host to produce viruses. A host can be a human, animal, plants or even bacteria.

A VIRUS has FOUR IMPORTANT PARTS.

Okay. So at this point, you should remember that viruses are non-living. Now let me show you the kinda simple parts of the a typical virus. We have the (1) nucleic acid, (2) protein coat, (3) envelope and (4) spikes.

The four important parts of a virus.
The four important parts of a virus.

Let’s describe each part. The nucleic acid (which is either DNA (deoxyribonucleic acid) or RNA (ribonucleic acid)) is known as the genetic material of the virus as it carries the main information responsible for its survival. It functions like the battery of a car. Without the battery, the car won’t function and will be useless in traveling/commuting. The protein coat (or technically known as capsid) encloses the nucleic acid. Its main function is to protect the nucleic acid. The envelope is the exciting part of the virus. It is composed of the cell membrane of the host and a little bit of viral proteins. This means that the envelope was created when it has successfully entered the host cell. Envelopes help the viruses avoid the immune system of the host. But take note that not all viruses have envelopes. Others do not possess and hence, they are called as naked viruses ;-). The spikes, just like the envelopes, are not always present in a virus. Spikes are proteins that are part of the capsid and envelope, which help in attaching to the host. It’s like the spikes of your favourite football shoes (the cleats). Yup. These were attached to the shoes to have a good grip of the ground. Just like the spikes of the virus. =)

So.. you should be imagining something like this:

Please don’t mind the aesthetic value of this. It’s a cartoon anyway =D. What’s important is that you now know that viruses have these parts (except when it is a naked virus) and these help them attack their hosts.

Reference: Lodish H, Berk A, Zipursky SL, et al. 2000. Viruses: structure, function, and uses. In: Molecular Cell Biology 4th Edition (WH Freeman Ed.). Available from https://www.ncbi.nlm.nih.gov/books/NBK21523/

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