What is a virus — what makes viral illnesses so difficult to treat?


What is a virus? And what makes viral illnesses so difficult to treat?


Viruses are a very simple kind of germ. They are smaller and simpler than other common germs, such as bacteria and fungi. They cause illnesses ranging from mild — like the common cold — to potentially fatal. This includes diseases such as smallpox, influenza, Ebola and HIV.

When viruses infect our cells, they take over a cell’s “machinery.” The cell can’t carry out its normal life-sustaining tasks. Instead, the host cell becomes a virus-manufacturing plant, making viral parts that reassemble into whole viruses and infect other cells. Finally, the host cell dies. Here is an illustration showing how a virus takes over a host cell:

Six steps to a viral takeover:

Virus SHR Figure 2

To enter a host cell and reproduce, most viruses follow some variation of these basic steps.

You ask why viral infections can be so difficult to treat. Not all are. And there are different reasons why some are, indeed, hard to treat.

Many common viral infections get attacked and eliminated by our immune system. For many of these infections, like those that cause the common cold, we don’t actually have (or need) anti-viral drugs.

Other common infections can be eradicated by the immune system in some people, but not in others. In that latter group, anti-viral drugs can assist the immune system in winning the war and eradicating the virus. The viruses that cause hepatitis B and C are examples.

Still other viral infections have tricks that make it impossible (currently) to eliminate them. Neither our immune systems nor anti-viral drugs can get rid of them, and they remain with us for the rest of our lives. Sometimes they remain “asleep” in our bodies, causing no damage. Other times they periodically awaken and cause symptoms; a cold sore caused by a herpes virus is an example. Anti-viral medicines sometimes can keep them dormant, or make them go back to sleep.

Another reason that some viral illnesses are hard to treat is that sometimes it’s not the virus that makes us sick; it’s our immune system. Our immune system is like an army: When it attacks a virus, it uses lots of artillery. Unfortunately, that artillery can also damage our own tissues. The symptoms from many viral infections are the “collateral damage” done to us by our own immune systems.


Finally, viruses reproduce so rapidly that they have plenty of opportunity to change their genetic stripes with each new generation. This allows them to develop resistance to whatever drugs or vaccines we throw at them.

Who is winning the war, we or our viruses? Over the past century we have eliminated or greatly reduced many viral illnesses through developing vaccines and anti-viral drugs. On the other hand, completely new viral infections have emerged, such as HIV. And the remarkable growth in global travel has made it easier for viral infections to spread.

So I’m not sure if we’re winning the war. But I am sure of one thing: Without medical research, we would have little chance of winning. And in my opinion, we’re not spending enough on research.