Is a virus alive?

Nicholas Landau nlandau at eden.rutgers.edu
Wed Feb 19 10:41:27 EST 1997

kr1 at PGSTUMAIL.PG.CC.MD.US (Karl Roberts) writes:

>Viruses can, without too much discussion, be considered acellular 
>biological entities. Since the concept of what constitutes life is still 
>basically unresolved and subject to personal interpretation, it is 
>probably best to think of viruses in this fashion. Obligate intracellular 
>parasites can include viruses, chlamydiae, mycoplasmas, and possibly even 
>prions and viroids, if you wish...viruses even have their own system of 
>classification, separate from other entities. You decide, and let us know.

Gotta disagree.  The virus itself is incapable of any biological
function.  This is not simply a matter of growth conditions, as is
the case of the cellular obligate intracellular parasites, some of
which can be raised in the lab under highly specific conditions, without
the presence of a host.

Even once viral nucleic acids have entered a host cell, the virus
itself does not conduct biological activity.  It simply modifies
the biological activities of the host.

Geneticists love to refer to virus, transposons and viroids as organisms,
because they have genomes.  For a geneticist, this is all that matters.
As a microbiologist, I see life as more complex than simply the presence
of a certain molecule, such as DNA.

Of course, nothing stated here is unknown to the proponants of counting
virus as living, and so nothing is resolved.

So goes science.

Nick Landau

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