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SPEAKER: This is the
virus SARS-CoV-2.
Its name stands for Severe
Acute Respiratory Syndrome
Coronavirus 2.
You may have heard
it called just
the coronavirus, or COVID-19.
Coronaviruses are
actually a family
of viruses that
include SARS-CoV-2,
and COVID-19 is the name of
the disease caused by it.
Coronaviruses infect
humans and other animals.
In humans, they cause the
common cold and, in some cases,
more serious
respiratory diseases.
All coronaviruses,
including SARS-CoV-2,
have a genome made of
a single strand of RNA
which is surrounded
by a membrane made
of lipids and proteins.
This membrane is
called an envelope.
Coronaviruses are
named after what
looks like a crown
of protein spikes
that stick out of
their envelope.
Coronaviruses enter
the body mainly
through the mouth or nose.
The virus then has to
get inside a human cell.
The protein spikes in
the virus's envelope
attach to specific proteins
on the surface of a cell.
This causes the virus's
membrane to fuse
with the cell's membrane,
releasing the virus's RNA
genome into the cell.
The cell's ribosomes translate
the virus's RNA into proteins,
including viral RNA polymerase.
The RNA polymerase
transcribes the virus's RNA,
making more RNA copies that
are translated into proteins.
It also makes more copies
of the virus's whole genome.
The new viral
genome and proteins
combine to make a
new virus that is
packaged into an envelope
formed from the cells membranes.
Newly-formed viruses travel
to the cell's surface
and are released
outside the cell.
These viruses can
infect other cells
or leave the body in
mucus and saliva droplets.
This can all happen even if
a person doesn't feel sick
or show symptoms of disease.
A fever or coughing are usually
signs that the immune system
is fighting the infection.
The production of
new viruses continues
until the body's
immune system is
able to eliminate the infection.
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