The severe acute respiratory syndrome
or SARS-Coronavirus II virus,
is an encapsulated virus which measures,
approximately 125 nanometers in diameter.
It contains a single strand
positive sense RNA genome,
measuring 26 to 32 kilobytes,
it is the largest of all RNA viruses.
The SARS-Coronavirus II contains,
four structural proteins,
the first three are the
“S-Protein” or “Spike” protein,
“E-Protein” or “Envelope” protein
and “M-Protein” or “Membrane” protein.
Together, these three proteins constitute,
the viral envelope, which is
so characteristically seen,
by electron microscopy.
The lipid membrane is next
in the structure of the virus
and then the “N-Protein,” is
the nuclear capsid protein,
this encloses and provides
attachment or complexing points,
with the RNA strand the RNA genome,
it also helps regulate the RNA synthesis.
The S-protein or spike protein,
is perhaps the most infamous or perhaps famous,
in terms of the science and discovery
involving the SARS-Coronavirus II virus.
It is an appearance club
shaped or even crown like,
when seen from the surface on
scanning electron microscopy.
It is, of course, responsible
for the binding of the virus,
to its target cells via the
acetylcholinesterase II receptor,
on epithelial cells and
including some endothelial cells,
in the host cell membrane.
It is also the target of most current
vaccines against the SARS-Coronavirus II.
The E-protein or envelope protein,
is responsible of course for viral assembly
and the M-protein for membrane
also for viral assembly,
as well as participating in release
of newly formed virions or viruses,
from their target cells.
As you can imagine, there is an
incredible amount of discovery ongoing,
for this particular virus as it
is causing the global pandemic,
we know as COVID-19.
Yet, more remains to be described
as we go further into understanding,
the impact and structure of
this very important virus.