Science and Environment

Viral intelligence: A no-brainer

STAR SCIENCE - STAR SCIENCE By Eduardo A. Padlan, Ph.D. -

September 29, 2005 | 12:00am

In the Wizard of Oz, the Scarecrow sings:

"…I would not be just a nuffin’
My head all full of stuffin’
My heart all full of pain
I would dance and be merry
Life would be a ding-a-derry
If I only had a brain."

Obviously, the Scarecrow believes that his life is meaningless because he does not have a brain and that life would simply be great if he had one.

And, of course, there is Man, who believes that he is the superior being on Earth because he has the biggest brain. We believe that we are the dominant species because of our superior intelligence. We maintain that the bigger the brain, the higher the intelligence. (Einstein would dispute that – his brain was smaller than usual.)

But is having a brain really necessary to have a meaningful life? Do we even have to have a brain to be considered intelligent?

There are numerous creatures that do not have brains, for example, viruses, bacteria, protozoa, fungi and others that do not have even the semblance of nervous tissue. Yet they exist and have existed for many millions, perhaps billions, of years and, in the battle for survival, they could defeat even us, the brainiest creatures on Earth.

Let’s consider the viruses.

Viruses are very simple beings. They are total parasites – unable to survive on their own – and depend on host organisms for the molecules that they need to carry out the chemical reactions that they require, very often even the ones needed to reproduce themselves. We might even question whether they are alive or not. But they victimize all living things – plants and animals alike, even bacteria.

Viruses come in different shapes and sizes, and all are very small. The simplest viruses are nothing but a strand of nucleic acid (some viruses have DNA for their genetic material, others have RNA), enclosed in a protein coat. The genetic material of simple viruses codes for only a few proteins, sometimes just one (for only the coat protein, in the case of satellite viruses which require the presence of other "more complete" viruses). Some viruses encase themselves with lipid membrane, taken from the cell they had just victimized. Some viruses kill their hosts (we all know about the AIDS virus); some damage or disfigure their hosts for life (polio, smallpox, and others). Some lie "dormant" inside their hosts (sometimes for many years); an example is the virus that causes chicken pox, which could hide in our nerves and resurrect itself and cause shingles many years later. Some even insert themselves into the genetic material of their hosts. (Yes, we can be sure that we, too, have viruses inserted in our DNA.)

To perpetuate themselves, viruses move from host to host. They are very clever about this. The cold virus, for example, causes us to sneeze; the spray that results causes the virus to be dispersed in the air and when inhaled by an individual nearby provides the virus with a new host. The AIDS virus is even more clever. It is transmitted via body fluids and its main mode of transfer from victim to victim is probably the most pleasurable activity known to man – sex. But the hepatitis B virus surpasses the AIDS virus in this regard. The hepatitis B virus is also transmitted through body fluids, but it is one hundred times more infective than the AIDS virus.

And viruses have devised clever ways of evading our immune system. Some mutate and alter their "appearance" (their surface molecules) so that our immune system can no longer recognize the "new" virus. (Our immune system has memory and it remembers, by their surface molecules, germs that it had encountered before.) This is the reason why we can catch cold repeatedly, or get the flu every year. Some viruses hide inside our cells (like the hepatitis viruses that hide inside the liver and move from liver cell to liver cell, thus not exposing themselves to the immune system). In regard to evading the immune system, the AIDS virus is the most clever: it targets a very important component of the immune system, the helper T cell. Essentially, what the AIDS virus does is destroy the immune system, leaving its victim helpless. But the AIDS virus does not kill its victim until 11 years after infection (on average), so that the victim has ample time to transmit the virus to other unsuspecting hosts.

Can we say a virus is intelligent? Of course! It’s a no-brainer. The Scarecrow has nothing to complain about.

Eduardo A. Padlan has a Ph.D. in Biophysics and was a research scientist at the (US) National Institutes of Health until his retirement in 2000. He is currently an adjunct professor in the Marine Science Institute, College of Science, University of the Philippines Diliman. He is a corresponding member of the National Academy of Science and Technology, Philippines. He can be reached at [email protected].