Cui, J., Li, F. & Shi, Z. Origin and evolution of pathogenic coronaviruses. Nat Rev Microbiol 17, 181–192 (2019). 
Retrieved from [doi.org/10.1038/s41579-018-0118-9](https://doi.org/10.1038/s41579-018-0118-9) 

University of Michigan - Ann Arbor

"Coronaviruses belong to the Coronaviridae family in the Nidovirales order."
Coronaviruses are named for the crown-like spikes on their surface. There are four main sub-groupings of coronaviruses, known as alpha, beta, gamma, and delta. 
Coronaviruses are ubiquitous among humans and animals. These viruses are enveloped, nonsegmented, positive-sense RNA viruses and have
the largest identified viral RNA genomes, with an approximate
length of 30 kilobases.

Coronaviruses

Coronaviruses that infect animals, such as bats, can evolve into viruses that infect humans, and these types of coronaviruses are often highly pathogenic in humans. They often result in pneumonia and fatal outcomes. Examples of evolved coronaviruses include: SARS-CoV-1, MERS-CoV, and SARS-CoV-2, all of which are beta coronaviruses.

Evolved Coronaviruses

Origin and evolution of pathogenic coronaviruses

Ogimi, C., Kim, Y. J., Martin, E. T., Huh, H. J., Chiu, C. H., & Englund, J. A. (2020). What’s New With the Old Coronaviruses?. Journal of the Pediatric Infectious Diseases Society.
https://academic.oup.com/jpids/advance-article/doi/10.1093/jpids/piaa037/5823148

What’s New With the Old Coronaviruses?

- Transmission
- Communicable Period
- Fatality
- Control Strategies
- Secondary Infections
- Patient Comorbidities
- Patient Outcomes
- Signs
- Symptomology
- Case Demographics of Patients
- Categorized by Geographic Location
- Time from Onset to Reporting
- Shedding duration
- Viral load over time
- Immunity
- Morbidity

Important clinical and laboratory details of coronaviruses

Coronaviruses were first discovered in birds in 1937.
Human coronaviruses were first identified in the evaluation of common cold in the mid-1960s.

The first discovery of Coronaviruses

The viruses were firstly divided into these genera based on serology but are now grouped by phylogenetic clustering.
1. alpha
2. beta
3. gamma
4. delta

 Main sub-groupings of coronaviruses

Common coronaviruses are viruses that cause mild to moderate respiratory illness in humans and is often responsible for upper respiratory tract disease and the common, seasonal cold. Most people are infected with a common coronavirus during their lifetime and recover on their own without treatment. They are found worldwide in temperate and tropical countries, as well as low-, middle-, and high-income countries.
HCoV infection can occur at any time of the year, with unpredictable year-to-year patterns, and outbreaks are reported in some years and in certain parts of the world. All common coronaviruses species may circulate yearly and even simultaneously, with the highest rates of HCoV infection seen in winter and spring months in temperate climates.

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