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Spring 2004 - Article 4

From The Lab
Viruses vs. Bacteria

Even though both are microscopic and both can make you sick, there is quite a difference between a virus and bacterium. We will look at each organism over the next two issues of Essentially Speaking, starting today with viruses.

A virus is a microorganism that needs a host (human, animal or other living organism) to propagate. They may or may not have an outermost spiky layer called the envelope (see illustration). Contrary to what you may think, naked viruses are actually stronger and more resilient than enveloped viruses and therefore are tougher to kill with common disinfectants (quats). All viruses have a protein coat and a core of genetic material, either DNA or RNA, inside.

Viruses are essentially miniature machines that live to copy themselves, often with devastating consequences for the host. They have no independent metabolic activity on their own (unlike bacteria). A virus enters a cell of a living plant or animal host and commandeers its protein manufacturing capabilities to replicate itself. The virus provides the genetic code for replication and the host cell provides the necessary "raw materials" for the virus to grow.

After producing copies of itself, a virus leaves a cell by either budding or lysis of the cell. Budding is a process by which the new virus "buds" out from the cell surface a few at a time. This process is not harmful to the cell. Lysis occurs when so much virus is produced inside the cell that it explodes. Smallpox lesions and herpes blisters are examples of lysis.

Viruses serve no benefit to living organisms other than population control. Pandemic flu outbreaks can kill millions of people, as evidenced in the Spanish flu of 1918 - 1919 that killed from 20 to 50 million people. The HIV virus has killed millions too. What makes viruses so hard to control is two-fold: they easily mutate and they can't be controlled with antibiotics. Vaccines are the only answer to their devastating consequences, as has been demonstrated with the elimination of polio and smallpox.