COVID-19: THE VIRUS
What's in a name?
"COVID-19" & "coronavirus":
The term "COVID-19" stands for Corona Virus Disease. Previous terms used include "2019 novel coronavirus" and "2019-nCoV." Both "COVID-19" and "coronavirus" refer to the actual disease itself rather than the virus that causes illness.
SARS-CoV-2:
SARS-CoV-2 virus refers to the virus that causes the disease. SARS-CoV-2 stands for severe acute respiratory syndrome coronavirus 2. This name comes from the fact that the virus is genetically similar to the coronavirus that caused the 2003 SARS outbreak (SARS-CoV).
Define Coronavirus
Coronavirus is actually the name of a specific category of viruses. The name is derived from the shape of the virus, which appears with a crown (also known as "corona" in Latin) of spikes on its surface. Viruses in the coronavirus group usually cause mild to moderate illness in the respiratory tract, aside from severe exceptions such as COVID-19. Other well-known examples of viruses in the coronavirus category include the SARS virus, the MERS virus, and even the virus that causes the common cold.
Characteristics of Coronavirus
To be classified as a "coronavirus," there are specific characteristics that a virus must demonstrate:
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Large, single-stranded RNA
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Corona-shaped viral envelope​​
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"Corona-shaped" refers to the ​crown of protein spikes that cover the surface of the virus.
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Helical capsid
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This means that many rod-shaped capsomers are bound together in order to form hollow discs. These hollow discs then join together in order to form one continuous helix. Inside the hollowness, there is an interior cavity that holds the nucleic acid.
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Human Coronavirus
The category of human coronaviruses was first identified in the mid-1960s. Within this category, there are four main sub-groups of coronaviruses: alpha, beta, gamma, & delta. As of the present day, only seven coronaviruses have been identified to have the capability to infect people:
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229E (alpha coronavirus, common)
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NL63 (alpha coronavirus, common)
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OC43 (beta coronavirus, common)
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HKU1 (beta coronavirus, common)
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MERS-CoV (beta coronavirus, causes Middle East Respiratory Syndrome)
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SARS-CoV (beta coronavirus, causes severe acute respiratory syndrome)
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SARS-CoV-2 (causes COVID-19)
New human coronaviruses can evolve from ​coronaviruses that infect animals, as seen with MERS, SARS, & COVID-19.