What are viruses, and how do they work?

Right now, it is hard to think. That sentence was going to say "right now, it is hard to think about anything other than COVID-19" ... but I think the above is probably truer.

But since we all have viruses on our minds anyway, maybe it's an opportunity to learn more about these interesting little "creatures".

I say "creatures" because unlike other microbes - like bacteria and fungi - viruses themselves are not technically alive. On their own, they can't do too much. But given access to a suitable living host (like us) they can replicate and, as we know too well, wreak havoc.

So what are viruses made of? They're surprisingly simple for something that can cause so much trouble.

At the centre of each viral particle is its genome - either DNA or a similar material called RNA. Surrounding that is a coat of proteins known as a capsid, and then, for some viruses (like our current foe) there is a lipid envelope (this is the bit that is destroyed by soap, so wash your hands!).

When we talk about viruses words like "infection", "disease", "illness" and "deadly" are used a lot - and for good reason. But there are, believe it or not, actually some good and useful viruses. Those that immediately spring to mind are bacteriophages.

These are viruses that infect bacterial cells, and the human body is home to plenty of them. They've been found on our skin, in our lungs, and through our digestive system.

These phages help to protect us from infection with different types of bacteria, and we're now taking advantage of them.

Phage therapy is used to treat bacterial infections - and is of great interest as we see the emergence of more and more antibiotic resistant bacteria. Phages are, however, extremely specific in the strain of bacteria that they infect, so finding or engineering the right one for a specific infection is a challenge. Viruses are also being used in biotechnology and medical research.

The thing that makes viruses such a pain - that they can attach to and infect specific cells - also potentially makes them a really useful tool.

One example is the development of viruses that can specifically target and destroy tumour cells, as a novel cancer treatment.

Viruses are also being used as delivery vehicles for things like gene therapy, which works by introducing genetic material into target cells.

Not all viruses are bad. But this coronavirus sure is a doozy.

Dr Mary McMillan is a lecturer at the School of Science and Technology, University of New England