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What is Coronavirus? Definition, History, Origin and Classification

What is Coronavirus?

Coronavirus is a name given the group of related RNA viruses that cause disease in birds and mammals, including humans (Human beings also fall in mammal category). Coronavirus mainly cause respiratory infection. It is not a name of a single virus but its a family of viruses.

Do you know that common cold is also a type of coronavirus disease but it caused by another types of coronaviruses that we will study later in this topic.

The scientific name of Coronavirus is Coronavirinae.


Most Recent Common Ancestor (MRCA) of Coronavirus have existence in 8000 BCE. The Most Recent Common Ancestor of Alpha Coronavirus existed at above 2400 BCE. Beta Coronavirus at 3300 BCE, Gama Coronavirus at 2800 BCE and Delta Coronavirus at 3000BCE. The bats & the avian species are the main reason of hosting Coronavirus for a long time.

Coronavirus first discovered in 1930s in chickens with respiratory infection caused by IBV (Infectious Bronchitis Virus, a species of Coronavirus).

After few years later, In 1940s two more species of Coronavirus discovered MHV (Mouse Hepatitis Virus) in mice and TGEV (Transmissible Gastroenteritis Virus) in pigs.

Human Coronavirus were discovered in 1960s in nose of a boy with common cold.

HCoV-229E (Human Coronavirus 229E) ( H for Human, Co for Corona and V for Virus) and HCoV-OC43 (Human Coronavirus OC43) were discovered.

Other human Coronaviruses have since been identified, including SARS-CoV in 2003, HCoV-NL63 in 2004, HCoV-HKU1 in 2005, MERS-CoV in 2012, and SARS-CoV-2 in 2019( Cause COVID-19 ).

Don’t confuse we will study all types of Coronaviruses in this section later.


The Coronavirus get its name from Latin word “Corona” which means “Crown” because of crown like projection on their surface. It is first found in Wuhan a city of China on 31st Dec. 2019.

  • Many Human Coronaviruses have their origin in bats.
  • MERS-CoV emerged in human from bats through intermediate host of camel as shown in picture.

Classification of Coronavirus:

Coronavirus is divided into 4 categories:

  1.  Alphacoronavirus
  2.  Betacoronavirus
  3.  Gamacoronavirus
  4.  Deltacoronavirus

  1. Alphacoronavirus – it has 8 species.
  • AlphaCoronaVirus 1 also called Transmissible Gastroenteritis CoronaVirus (TGCV) – It infects Pigs.
  • Human CoronaVirus 229E (HCoV-229E) – It infects Human.
  • Human CoronaVirus NL63 (HCoV-NL63) – It also infects Human.
  • Miniopterus Bat CoronaVirus 1 – This virus infects bats
  • Miniopterus Bat CoronaVirus HKU8 – This virus also infects bats.
  • Porcine Epidemic Diarrhea Virus – This virus infects pigs.
  • Rhinolopus Bat CoronaVirus HKU2 – This virus infects bats.
  • Scotophilus Bat CoronaVirus 512 – This virus also infects bats.

2. Betacoronavirus – Betacoronavirus have 9 species.

  • Human coronavirus OC43 – This species of Coronavirus infects human.
  • Hedgehog Coronavirus1 – This Coronavirus infect Bats.
  • Human Coronavirus HKU1 – It infects Human
  • Middle East Respiratory Syndrome Coronavirus (MERS-CoV) – it infect Human, bats and camel.
  • Murine Coronavirus – This also called (MCoV) and it mostly infect Mice.
  • Pipistrellus Bat Coronavirus HKU5 – It infect Bats
  • Rousettus Bat Coronavirus HKU9 – It infect Bats
  • Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) – This virus cause SARS disease and infects bats but in 2019 its 2nd species found SARS-2 which infects Human.
  • Severe Acute Respiratory Syndrome Coronavirus 2(SARS-CoV-2) – It is a type of SARS Coronavirus found in Wuhan in 2019 and it infects Human.
  • Tylonycteris bat Coronavirus HKU4 – infect Bats.

3. Gamacoronavirus – It has 2 species.

  • Avian Coronavirus also called Infectious Bronchitis Virus (IBV) – It infect Chickens.
  • Beluga Whale Coronavirus SW1 – This virus found in Beluga Whale.

4. Deltacoronavirus – It also has 2 species.

  • Bulbul Coronavirus HKU11 – This virus found in Chinese bulbuls.
  • Porcine Coronavirus HKU15 – This virus infects pigs.

Alphacoronavirus and Betacoronavirus species mostly infect mammals and Gamacoronavirus and Deltacoronavirus species mostly infect Birds.

Human Coronavirus

Doctors currently recognise 7 types of Coronavirus that can infect human.

These four types produce mild symptoms and can be cured at home.

  1. HCoV-229E
  2. HcOV-NL63
  3. HCoV-OC43
  4. HCoV-HKU1

And another three that produce serious symptoms.

  1. MERS-CoV – This virus cause MERS disease.
  2. SARS-Cov – This virus cause SARS disease
  3. SARS-Cov-2 – It is the new version of SARS that take birth in 2019 in Wuhan city of China. It cause COVID-19 disease.

In the below picture you can see that first four coronavirus that cause only common cold and can be cured at home. If you suffered from common cold that doesn’t means that you suffered from COVID-19 disease. If you have symptoms of SARS-CoV-2 than you should call the emergency services and seek medical treatment as soon as possible.

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