Definition
What is a coronavirus?
A coronavirus is a member of the Coronaviridae, a large family of enveloped viruses that infect mammals and birds. Under the electron microscope, club-shaped spike proteins on the surface give the particle a halo like the sun's corona, which inspired the name. Inside the envelope lies a single strand of positive-sense RNA about 30,000 bases long, among the largest genomes of any RNA virus; positive-sense means the host's ribosomes can read it directly as messenger RNA. The particle has four main structural proteins: spike, membrane, envelope and nucleocapsid.
The spike protein grips a receptor on the host cell and fuses the viral envelope with the cell's membrane; SARS-CoV and SARS-CoV-2 both use a receptor called ACE2. Seven coronaviruses are known to infect people. Four of them, 229E, NL63, OC43 and HKU1, circulate every year and cause common colds, occasionally pneumonia. Three that crossed over from animals, with bats the likely original hosts, cause severe disease: SARS-CoV in 2002 and 2003, MERS-CoV from 2012, and SARS-CoV-2, the cause of COVID-19, from late 2019.
Coronaviruses spread mainly in droplets and aerosols from the airways. Because the spike is the main target of protective antibodies, it was the antigen chosen for the COVID-19 vaccines, including the first mRNA vaccines.
Word parts
Where does the word “coronavirus” come from?
- corona
- crown, garlandLatin corona
- virus
- poison, slimy liquidLatin virus
Practice it
Where you'll meet it
Quizzes that use it
Related
Terms that go with it
- VirusA virus is a tiny infectious particle of DNA or RNA inside a protein coat that can multiply only by taking over the machinery of a living host cell.
- Viral envelopeA viral envelope is the outer lipid membrane, taken from a host cell and studded with viral proteins, that surrounds the capsid of some viruses.
- PandemicA pandemic is an epidemic that crosses international borders and spreads over several continents, typically infecting very many people.
- ZoonosisA zoonosis is an infectious disease that passes between animals and people, caused by a virus, bacterium, parasite or fungus carried by animals.
- mRNA vaccineAn mRNA vaccine delivers messenger RNA coding for a pathogen's protein, so the body's own cells make that antigen and train the immune system.
- RNARNA is a usually single-stranded nucleic acid, built with the sugar ribose and the base uracil, that carries and uses genetic information to make proteins.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- Fehr and Perlman, Coronaviruses: An Overview of Their Replication and Pathogenesis (Methods Mol Biol, 2015)
- CDC (archived): Common Human Coronaviruses
- WHO: Coronavirus disease (COVID-19)
- NCBI MeSH: Coronavirus
Last updated
Spotted a mistake? Tell us and we'll correct it.
Practice Virology
Free virology quizzes, with an explanation for every answer.
See the Quizzes