Wednesday, April 29, 2009

What is a virus?

The first question the swine flu epidemic brings to mind is, “What is a virus?” I know that there is a difference between getting a bacteriological infection and getting a virus. I know that one can be treated with antibiotics and the latter cannot. It wasn’t until a couple weeks ago that my sister told me that viruses are not alive. My doctor and biologist friends ardently confirm this. So that’s why they can’t be treated with antibiotics; the word “antibiotic” means “against life,” and viruses are not alive! Well, um, shrug, that’s where my knowledge stops and the questions begin. They sure seem to be a life force (a sort of consciousness). So if they are not life, what is life? And if they’re not alive, what are they?

Wikipedia has a long article detailing viruses. The article refers to them as “infectious agents”. They’re like little seed packets: RNA or DNA strands packed inside a protein case. In the influenza virus, the protein cases are covered in little spiky projections. These are protein, which help the virus attach to a cell and enzymes, which help the virus enter the host cell. Viruses can’t reproduce on their own. So, once they inject their RNA or DNA into the host cell, they co-opt the cell’s ability to reproduce. And then they reproduce so much that they weaken the cell and cause it to burst. This is like the seed pod opening and spreading its seeds. Thus the infection spreads. This activity requires no food, but it does require the host cell’s energy. And, although not self-mobile, they do adapt to the environment by shifting their protein casing, or mutating.

There are several classes of viruses, the one currently in the news being Type A Influenza. This type of influenza mutates more frequently than others. Saturday’s SFGate article stated, “Hospitals and public health departments throughout California, where six of the American cases have been found, were told Friday to increase surveillance of the rare strain of flu that combines genetic material from humans, pigs and birds.” Because this is a new virus that has evolved from animals to humans and has continued to spread from human to human, the World Health Organization’s pandemic alert is now at phase 4. According to the Centers for Disease Control and Prevention , people are potentially contagious for seven days after onset of the illness or while symptomatic. The virus is transmitted through coughing or sneezing but, according to the CDC, can be acquired by touching something that a sick person has touched. “We know that some viruses and bacteria can live 2 hours or longer on surfaces like cafeteria tables, doorknobs, and desks. Frequent handwashing will help you reduce the chance of getting contamination from these common surfaces.” Wait a minute. Back up. “Viruses…can live”?!

It appears that the verdict is not out on whether or not viruses are alive. While they don’t meet the requirements for life in the way that we normally think, they are so close as to be arguable. Scientific American has an excellent article that takes that to task. Perhaps we need to further define what life is?

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