Topics Covered: Issues related to health.
Types of human coronaviruses
What to study?
For Prelims: Coronaviruses- types, virus types which affect humans, symptoms and recent examples.
For Mains: Impact of certain viruses and the need for better preparedness.
What are coronaviruses?
Coronaviruses are a large family of single-stranded RNA viruses that cause diseases in animals and humans.
- Broadly, coronaviruses (CoV) are the largest group of viruses that belong to the Nidovirales order, which includes Coronaviridae among three others.
- Coronavirinae are one of the two subfamilies of Coronaviridea, with the other being Torovirinae.
- Coronavirinae can be further subdivided into alpha, beta, gamma and delta coronaviruses.
These viruses are named so because of spikes found on their surface that give them the appearance of a crown when looked through an electron microscope.
The first coronavirus was isolated in 1937 and it was the infectious bronchitis virus (IBV) that caused respiratory disease in chickens.
Coronaviruses which affect humans:
While there are hundreds of coronaviruses that cause diseases in animals such as pigs, camels, bats and cats, till date seven different types of coronaviruses have been identified that infect humans.
In the last two decades, more aggressive coronaviruses have emerged that are capable of causing serious illness and even death in humans. These include SARS-CoV, MERS and now SARS-CoV-2.
In 1965, scientists DJ Tyrrell and ML Bynoe were the first ones to identify a human coronavirus, which they isolated from the nasal washing of a male child who had symptoms of common cold. They termed the strain B814 and later in 1968 the term “coronavirus” was accepted.
Seven types that infect humans: Includes Two alpha coronaviruses (229E and NL63) and four beta coronaviruses (OC43, HKU1, MERS and SARS-CoV).
Coronaviruses from all four categories can be found in mammals. But, bat coronaviruses are the likely gene source of alpha and beta coronaviruses, while avian coronaviruses are the probable gene sources of gamma and delta coronaviruses.
When the human coronaviruses were first identified?
229E: Discovered in 1967.
NL63 and HKU1: First identified in the Netherlands in 2004.
SARS-CoV: 2003 in China.
MERS: 2012 in Saudi Arabia (transmitted by dromedary camels).
SARS-CoV-2: 2019 in Wuhan (source not yet known, possibly bats).
- Can Coronavirus infect animals?
- How are they classified?
- Types of Corona affecting humans?
- Why are they named so?
- Their discovery?
In the last two decades, more aggressive coronaviruses have emerged that are capable of causing serious illness and even death in humans. Discuss.
Sources: Indian Express.