The Southwest has been hit by two viral diseases in recent years: Hanta Virus spread by some kinds of mice and West Nile Virus, spread by our old nemesis, the mosquito. But what are viruses? They are smaller and simpler than bacteria, and whether they are considered to be alive or not is mostly a question of definition; a matter of where we draw the line between living and nonliving.
Viruses generally are considered escapees—bits of genetic material that
at some point escaped from their parent organisms. Such releases are common when
bacterial cells or those of other organisms break down, but only rarely does such a
segment of DNA or RNA have the makeup allowing them to enter another cell and use that
host cell to make copies of itself. Thereafter, natural selection takes over, wiping
out variants of the virus that are inefficient and multiplying those that efficiently
resist the defenses of the cell and have the ability to be passed on to other
organisms. Thus, like ourselves, our viruses are natural selection's
survivors.
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.