There has been a great deal of debate on the subject of viruses and whether or not they can truly be considered a life form. However, their effect on all living creatures cannot be denied, and as such it behooves us to study them intently and learn to combat them. Because they are invisible to the naked eye, they must be studied microscopically.
Viruses cannot reproduce on their own - they must invade a host cell to do so. This is a large part of the argument against their classification as living things - they "act" more like machines. But living or not, they are perfectly capable of wreaking tremendous havoc on the human population and must be understood. Science has so far been willing to put aside the semantics squabble in the interest of defending the general population from these efficient, fascinating invaders.
Viruses cause all manner of strange and unpleasant things to happen to an unwitting host. Most recently, they have come to the foreground of medical research thanks to H5N1 (Bird Flu), Ebola, rabies, and a host of venereal diseases (including HIV, herpes, and HPV). Mankind's history is rife with viral invasions, and nasty classics like smallpox have wiped out millions of people who never even knew what hit them. Even the common flu virus causes great grief by its sheer tenacity and pervasive nature - have you ever known someone who NEVER got the flu?
One of a virus' most unique features is its ability to "shift" or adapt to a new environment with alarming speed, allowing it to hop from one host to the next with barely a stop to reproduce in between. Thanks to modern microscopes (including the impressive electron microscope), we can now see the unique protective shell of proteins, called a capsid, which protects the inner workings of the viral "machine". Once identified and studied, this defense mechanism can often be made vulnerable to attack from a vaccine or antiviral agent.
Because viruses are so small (a fraction of the size of most bacteria), electron microscopes are the only means by which we can see their features clearly. Identifying a virus can help determine its origin, how it spread from one place to another, and what may be used to destroy it.
Virus study has been made popular in the works of Robert Preston ("The Hot Zone, "Demon in the Freezer") and other writers, and in movies ("Outbreak", "Warning Sign"). But take away the glitz and glamour, and you have a lethal agent capable of killing you in a matter of days before you even know it's there.
Viruses are very efficient at what they do. They are not bound by morality or ethics. They don't care about damage to their host. All they do is invade, multiply, and destroy.
Our greatest weapon against this terrifying efficiency is knowledge. Microbiology is the study of the amazingly small, unseen world that surrounds our environs, our bodies, even the air we breathe. Without the help of dedicated scientists and advancing microscopic technology, we would be utterly at the mercy of these invisible killers. As great as their potential to do harm may be, there is hope that one day we will find a way to use them in a beneficial manner.