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- Herausgeber: David Fickling Books
- Kategorie: Für Kinder und Jugendliche
- Sprache: Englisch
Join science expert Dr Ben Martynoga and illustrator extraordinaire Moose Allain on a fascinating, sometimes funny, and occasionally scary journey through the world of viruses.Explore the science behind viruses and the COVID-19 pandemic in a fascinating story of hijacked human cells and our own internal emergency services.Along the way, you'll learn what viruses are, how they work, and how we can overcome - or at least learn to live alongside - those that do us harm.
Das E-Book können Sie in Legimi-Apps oder einer beliebigen App lesen, die das folgende Format unterstützen:
Seitenzahl: 124
Veröffentlichungsjahr: 2020
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B.M. To Beda and Ghyll. Please don’t ever stop asking why.
M.A. To Karen, Connor and Spencer, the best possible people to be locked down with.
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The SARS-CoV-2 coronavirus that causes the COVID-19 illness is totally new to our world. Until November 2019 it hadn’t infected a single person, which means there’s still a lot that we don’t know about it. But scientists and doctors all over the world have launched a massive combined effort to find out how the virus works and – crucially – what they might do to stop it harming people. Knowledge about the virus really is changing all the time – which is exactly how science works – so while the facts in this book have all been carefully checked, some things may change before publication.
Contents
Foreword by Paul Nurse
Nobel Prize-winning biologist, director of the Francis Crick Institute, London
Because of coronavirus everyone has become interested in viruses, and if that includes you, this is the book you should read. SARS-CoV-2 coronavirus has changed the world for everyone, yet most of us only have a hazy idea of what viruses are. The Virus will tell you all about them. It is the essential introduction to these extraordinary life forms – the most abundant on our planet – that have a huge impact on the rest of the living world, including ourselves.
By reading this book you will discover that viruses are unbelievably small and that they can only make copies of themselves by invading the cells of other living organisms, in order to make hundreds, or even thousands, of copies of themselves. They are the ultimate parasite! The COVID-19 virus, like many of the other viruses that invade our bodies, can make us feel either mildly or, sometimes, very seriously ill. If we sneeze or cough, the virus is transmitted in water droplets and can infect someone else, and if this spread occurs rapidly it can lead to an epidemic or even a pandemic. 4
This book will inform you about how we can combat coronavirus, and where the virus comes from, but it will also tell you about many other viruses: ones that attack bacteria so they can no longer infect you, others that help bacteria make oxygen in the oceans, and yet more that might even help deal with climate change.
Reading this book is an adventure, an exciting journey through the strange world of viruses. It is easy to read, witty and humorous, informative and accurate, wonderfully illustrated. It shows how our immune systems combat viruses, how vaccines work, and maps out how we can deal better with pandemics in the future. If you want to know about viruses and coronavirus in particular, this is the book for you.
Jonathan Stoye FRS, virologist and senior group leader at the Francis Crick Institute, says:
‘Although there are more viral particles on Earth than stars in the universe, over the past six months one particular kind, the SARS-CoV-2 coronavirus, has imposed itself on our way of life. This book tells us how and why in a clear and accurate manner, readily understandable by all.’
Professor Stoye is the scientific consultant and fact-checker for The Virus.
There are millions of different kinds of virus in the world, and only a very small fraction of them can infect humans. Coronavirus is a term used to describe a large group of different viruses that can cause diseases in mammals and birds.
SARS-CoV-2 is the full name for one specific species of coronavirus that causes the illness COVID-19.
Throughout this book we refer to the SARS-CoV-2 virus as the COVID-19 virus.
The Riddle
What is smaller than a speck of dust but more terrifying than any monster?
What doesn’t have muscles but does have the power to stop all human activity?
What can’t move itself an inch but can travel round the world in days?
What has no brain but is cleverer than any scientist?
What wears a crown but definitely isn’t a king or a queen?
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13Hang on a minute. I’m not so sure about this riddle. You’re tiny and brainless – and you can’t even squirm or bite – why should we be scared of you?
OK, good point. We should be scared of you. You’re an evil little scumbag.
Yup, that’s all thanks to our incredible immune systems. Plus, we can destroy you before you even get inside us – all it takes is a bar of soap!
Yeah, too right. Once our scientists develop a vaccine, you’d better reconsider your ‘plans’ for world domination. And you can tell all those other little viruses that harm people – we’re coming for the lot of you.
Confused already? It’s not surprising. Viruses really are a whole set of riddles. How can they be bad and good? Deadly and essential? If they’re so small and fragile, how can they cause such havoc? And how can we call them clever when they’re just a bunch of dumb little chemical molecules?
So let’s try to make sense of these mysterious viruses. Since we really do have to share our world with them and the nasty diseases they cause, we’d better find out all we can about what they are, how they live and how they spread.16
Chapter One
What the Heck is a Virus?
And how can it possibly wear a crown?
You’ll already have gathered that viruses are very small. But the word ‘small’ doesn’t begin to cover it. Viruses are mind-bendingly tiny.
Hold your hand up to the light. Can you spot some extremely fine hairs on the back of your fingers? They’re about the narrowest thing you can see without a magnifying glass. You could line up 50 of them side by side and they’d still only fill up a millimetre on your ruler. Those hairs are small, but they’re massive compared to a virus.
If a coronavirus drifted in and landed on one of those hairs, it’d be the equivalent of a flea hopping onto the trunk of a big old oak tree.
Now, hold on to that image of the blown-up coronavirus. How big would that make your whole body? Well, the actual size of the virus is 100 nanometres* across. If we blow it up to flea size (1.5 mm), it’ll be 15,000 times bigger. And if we blow you up by the same proportion, supposing you’re 1.5 metres tall in the normal-sized world, that would make you 22.5 km tall in our blown-up world!
18Your head would be way up in the stratosphere, nearly three times higher than the peak of Mount Everest. Aeroplanes might accidentally hit you where it hurts.
And this brings us to one of the most mysterious and confusing of all the riddles about viruses like the COVID-19 virus. How can the equivalent of a flea biting an enormous giant, with its head way up above the clouds, send that giant to bed with a fever? And how could it possibly kill such a magnificently huge human being?
If that makes viruses sound even more potent than the deadliest poison, that’s because they can be. If we don’t stop them in their tracks, that is.
Here’s their trick. Unlike any poison we know of, when viruses get inside a body they multiply like crazy. That’s basically what they exist to do. They’re hell-bent on multiplying. Within a matter of days, one virus can turn into hundreds of millions of identical viruses. These copies can then spread through our bodies, making us ill and potentially infecting other people.
Sounds scary? Frankly, it is scary. But hang on in there, because we giants do have some highly impressive ways of fighting back. Before we get to those defences, though, let’s look at what a virus actually is.
19First things first: viruses are not cells.
Cells are what our bodies are made of. There are billions and billions of them, all working together to make each of your different organs – your heart, lungs, brain, skin and everything else. Each of those cells is a little living being in its own right.
In fact, all living things – apart from viruses – are based on cells. Animals and plants and many fungi are also made from lots of cells, while bacteria and other microbes are just single cells. We use the word ‘germ’ (or ‘pathogen’) to describe anything – a bacteria, a fungus, a protist† or a virus – that can infect us and make us ill. Except for the viruses, all of these are cells.
Viruses aren’t just simpler than cells, they’re less independent. Cells can make their own parts, produce the energy they need and actually make complete copies of themselves. Viruses can’t – at least, they can’t do it on their own. Instead, they’re the ultimate parasites. In order to survive and multiply, they rely completely on the cells of the other living things they infect.
The COVID-19 coronavirus is a fairly typical example of 20a virus. At its centre is a string of genes. You can think of these genes as working a bit like a set of computer programs that tell a robot exactly what it has to do in order to build and then operate another robot. Something as big and complex as a human being needs a lot of genes to build and run it: that’s why each of your cells contains about 22,000 of these gene-based ‘instructions’.
Our genes, and the genes of most other life forms, including many viruses, are made of a chemical substance called deoxyribonucleic acid. That’s a bit of a mouthful, so it’s usually shortened to DNA. The coronavirus’s genes are made from a similar chemical substance called ribonucleic acid, or RNA. Viruses have far fewer genes than we do: the COVID-19 virus only has 29 of them, but that’s enough to take complete control of the cells they infect and tell those cells precisely how to build lots and lots of new viruses.
21On the outside: The membrane envelope is a round bubble made from an oil-like substance called lipid.
It is studded with three different kinds of protein: the spike, envelope and membrane proteins.
On the inside: The virus’s all-important genes are part of one very long but very thin molecule of RNA.
Nucleocapsid proteins stick onto the RNA and coil it up, so it fits inside the virus.
22Coronaviruses hate soap because it’s very good at dissolving lipids, destroying their membrane envelopes. The lipid in the virus’s envelope layer is exactly the same stuff that makes up the membrane that surrounds and protects each of the cells in our bodies. But some viruses have no lipids in their outer shells; they just have proteins. However it’s made a virus’s outer shell protects its genes and gives it its distinctive shape.
Good point! Corona means ‘crown’ in Latin. And when scientists first used powerful microscopes to create images of coronaviruses, they saw a kind of ring, with loads of spikes sticking out. If you squint, it looks a bit like a crown.
And these spikes are seriously important for the coronavirus’s way of life. Just as a house has its own key, which fits just one matching lock, each kind of virus has its own specific way of ‘opening the door’ and getting inside the cells it likes to infect.
The COVID-19 virus’s spike proteins are its key, and the lock is a protein found on the outside of its favourite cells – scientists call it ACE2. Many of the cells in our bodies have 23ACE2 embedded in the membrane that surrounds them, including the cells in our noses, throats, windpipes (tracheas) and lungs, which is where the COVID-19 virus usually tries to infect us first.
Coronaviruses are so small that they can easily get into our airways. We might touch an infected surface and the viruses stick to our skin. If we then touch our face, the viruses on our fingers can transfer into our mouth or nose. Or we could even breathe in viruses suspended in the air that an infected person has coughed out. Once they’re inside the body, and the coronavirus bumps into a cell with the ACE2 protein, the coronavirus’s spike ‘key’ can fit snugly into the cell’s ACE2 protein ‘lock’. Then comes the nasty bit.
Because there isn’t really a ‘door’ attached to the ACE2 24‘lock’, the virus uses the ‘key’ to confirm it’s got the right cell and then basically tears a hole and fuses its membrane with the cell’s. Then it pours its RNA genes directly into the cell. Help!
Having a stranger barging into your home is disturbing for anyone. But, for a cell, having a virus force its way in is especially traumatic, because it’s likely to change that cell’s life for ever. In fact, some of them never recover from the experience, as we’ll see in the next chapter.
* A nanometre is really minuscule. There are one million of them in a millimetre.
† Protists are organisms that aren’t plants, animals, bacteria, fungi or viruses. That includes slime moulds, algae and various parasites, like the ones that cause malaria.
Chapter Two
The Ultimate Hijack
How the virus takes charge of our cells
Ready to do something a bit weird?
I hope so, because we’re going to shrink ourselves down until we’re about the size of a coronavirus. That means we will be 15 million times smaller than we are now, and about one hundred times smaller than a cell. That way we can actually get inside one of the cells on the inside of someone’s throat and see how the virus works. Hold tight, it’s going to be quite a ride.
Everyone OK? Going through the shrinker can feel strange and kind of disorientating …
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