Marie Pizzorno, an associate professor of biology and a molecular virologist, explains the differences between viruses and bacteria, how some bacteria are "good," and why it's difficult to predict the next epidemic.
Q: What is virology and what is the difference between viruses and bacteria?
A: Virology is the study of viruses. I am a molecular virologist and I specifically study viruses that infect eukaryotes, or higher-order cells, that have a nucleus in them, such as in plants, animals, funguses and insects. Bacteria are simple, one-celled organisms that don't have a nucleus, which is the part of the cell that stores the DNA. Bacteria have all of the machinery they need to carry out the basic processes of life. They can use energy; they can make new proteins; and they can replicate. Viruses are much more limited in that they do not have the capacity to be independent life forms. They need a living cell to infect. Typically, in a normal virus infection, the virus goes into the cell and takes over the cell's machinery. Instead of the cell making cellular stuff, it makes viral stuff. A single virus infection can produce anywhere from 100 to 10,000 new virus particles. So, viruses can replicate very quickly, which is why virus infections in humans tend to take off really fast.
Q: Where are bacteria found and when are they beneficial?
A: Bacteria live in the water, soil, on our skin and inside us. They are everywhere. Most people think all bacteria are bad, but they are not. We have bacteria in our guts that we are now learning actually make things that are important for our bodies. And anybody who has taken an antibiotic and wiped out all the bacteria in their gastrointestinal system, in their stomach, knows the negative effect of not having those bacteria there. The only time we really get upset is when bacteria are in a place they shouldn't be and in a part of our body where they're growing too much and causing an illness. So we take antibiotics to kill bacteria when we have pneumonia or bronchitis or other things like that. But for the most part bacteria do good things and killing off all the bacteria is not always in our best interest.