Page 4 - TBAS-Aug-2020

-4- TBAS August 2020 ....................

Since we have all been and maybe still are in self quarantine at home, and
all of our aquariums are spotless, and all of our breeders are set up, and there is
not a spec of dirt in any of the filters, it may be a good time to talk about viruses.
Viruses are interesting creatures. Virus is a Latin term meaning “poison,
sap of plant, slimy liquid.” The earliest use in English was in 1728. Viruses have
been called “organisms at the edge of life.” Some say that viruses are not alive.
One definition I found was, “A virus is a submicroscopic infectious agent that
replicates only inside living cells of an organism such as an animal, plant, or
bacteria.” Inside the virus is a packet is called a viron that contains DNA or RNA
enclosed in a protein coat called a capsid. The viron has no digestive system,
nervous system, or nucleus as a typical animal or plant cell would have. A virus
cannot reproduce on its own. This is why some say that viruses are not “alive” in
the strictest sense of the word. Viruses reproduce by injecting their DNA or RNA
into a host’s cell and programming the cell’s machinery to produce more viruses.
The cell eventually explodes releasing new viruses to infect more cells.
Viruses are very, very small, about 1/100 the size of a bacteria. They have
a diameter of 20-300 nanometers. A nanometer is one billionth of a meter.
Escherichia coli that lives in our intestines is 1100 nanometers wide and 6000
nanometers long. You cannot see a virus with a regular light microscope; you
need an electron microscope.
There are about 5,000 different viruses (so far). A virus can be very specific
to the host it infects and what type of cell it infects. In humans, measles, polio,
influenza, smallpox, and covid-19 are all caused by viruses. They have been
found in almost every type of ecosystem. Viruses are the most abundant biological
entity in the aquatic environment. There are about 10 million viruses in a teaspoon
of sea water (I may never go to the beach again!). There are over 125 different
viruses that affect fish.
There are many viruses that affect food fish and cold-water fish such as
goldfish and koi. As fish keepers you may have seen some of these:
Spring Virena of Carp (SVC)
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