Stringy ebola viruses
I recently published a picture of Middle East Respiratory Syndrome (MERS) virus attacking a monkey cell, just because I found the picture astonishing. We’re all already familiar with the stringy ebola virus (below), because we fought it (and beat it) right here in the USA a few months ago. It’s a string, usually shown with a tangle at the top of the picture. It’s actually just stringy; the tangle is incidental and accidental.
Here (above) is a picture of ebola viruses (blue) being produced by a monkey cell (yellow). This is a real picture, made by some type of electron microscope and colored so we can tell the difference between the cell and the viruses.
When a virus infects a cell, it sends that cell a simple message: Make more viruses.
Viruses have just one purpose: to reproduce. And they can’t do that without a cell.
A virus is just a string of genetic material (either RNA or DNA) covered by a protective protein sheath. They aren’t even alive, because they have no organs, they cannot ingest or digest food, and they have no respiration or metabolism. They are just dead chemicals. The genetic material, in fact, is a single molecule.
However, when a virus comes in contact with a suitable host, chemicals on its surface attach it to a cell wall and bore through it to the inside of the cell. Once inside the cell, the viral genetic material takes advantage of the cell’s machinery to reproduce and make thousands of copies of itself. You can see those copies exiting the monkey cell above.
There are very many different viruses.
Viruses don’t all work exactly the same way, of course. Some of them stay in the infected cell until it fills up and bursts.
Either way, the freed viruses move on to infect other cells and repeat the process over and over.
Viruses are parasites.
All viruses are parasites, which seems a strange thing to say after I told you they aren’t even alive. But it’s true. Purely by chemical means, they enter your body (or something else’s body) and hijack your cellular machinery for their own purposes while probably making you sick. The sickness may be as mild as a cold or flu or as serious as HIV or ebola, depending on the virus.
They are everywhere. They exist deep in the oceans and deep under the ground, high in the air, in tropical forests and antarctic ice. They attack probably every type of living organism on the planet, from bacteria to humans to trees to toadstools and everything else; but most of them will attack only a single host. There are more kinds of virus than there are of all living organisms put together. This means around ten million different kinds, at least.
Viruses reproduce imperfectly (with a lot of mutations), so they evolve just like living things, only faster. A person can be infected with a single strain of HIV and have several strains a few years later. That’s one of the reasons viruses are so difficult to fight.
It’s also why the Center for Disease Control and Prevention has to guess which strains of flu are likely to be active next winter in time to begin making inoculations several months in advance. Sometimes they guess wrong.
But they guess right most of the time. In addition, a sigle flu shot is designed to protect against all of the three most likely strains. This means, even if they don’t get it exactly right, you’ll probably still be covered anyway.
Be sure to get your shots when it comes time. I will, too; but I still don’t want you coughing and sneezing on me.