Re-Is a virus alive?

Steven Projan PROJANS at war.wyeth.com
Mon Feb 3 07:50:11 EST 1997

This is a frequently asked question and debated issue.  Just because
virus are parasites requiring a host cell in which to replicate does
not make them non-living as there are many examples for bacteria
(which most of us would consider alive) which are obligate
intracellualr pathogens.  But if we consider viruses as living
entities than where do we draw the line?  What about plasmids, which
are composed solely of DNA and replicate inside cells (usually
bacteria) but do not become encapsidated live viruses?  In 1980
Richard Novick wrote an article for Scientific American in which he
referred to plasmids as the smallest of organisms.  If we accept
plasmids as organisms then where do we put prions?   And what about
those degenerate bacteria, the mitochondria and cholorplasts, do we
consider these the formerly living, the undead, really nice
parasites, symbionts?

Perhaps we should just consider that there is a continuum between
what is the biochemical and what is the living.  Perhaps life is like
pornography - I believe it was Supreme Court Justice Hugo Black who
said that he don't know how to define pornography but he knew it when
he saw it.

Steve Projan
Wyeth-Ayerst Research

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