Coronaviruses are a large group of RNA viruses that cause respiratory and gastrointestinal illnesses in both mammals and birds. Although the term gained widespread attention recently, this family of pathogens has been known to science for decades. The name is not based on the illness or discovery location, but rather a direct description of its physical structure. Understanding the origin of the name is rooted in the early days of electron microscopy and virology.
The Visual Origin of the Name
The name “coronavirus” is derived from the Latin word corona, which translates to “crown” or “halo.” This name was chosen because of the virus’s distinctive appearance when viewed under a transmission electron microscope. The outer surface of the viral particle, known as the virion, is adorned with numerous projections.
These projections are made of glycoprotein spikes embedded in the viral envelope. The spikes project outward from the surface, creating a fringe or aura around the virus’s core. This visual effect strongly resembles the solar corona, the glowing plasma atmosphere of the sun, or the points of a royal crown. This specific structure, including the viral envelope and the spike proteins, universally defines this entire group of viruses.
Historical Naming and Discovery
The study of coronaviruses began with the identification of animal and human pathogens in the mid-20th century. One of the earliest known coronaviruses was the infectious bronchitis virus (IBV) found in chickens, discovered in the 1930s. Human coronaviruses were first isolated in the 1960s, including strain B814 from a common cold patient in England and strain 229E in the United States.
In the late 1960s, virologists June Almeida and David Tyrrell first proposed the collective name “coronavirus.” They observed the unique crown-like morphology shared by human cold viruses and previously known animal viruses, such as the mouse hepatitis virus. An informal group of virologists published the name in the journal Nature in 1968, officially establishing the nomenclature. The name was formally accepted as a genus name by the International Committee for the Nomenclature of Viruses in 1971.
The Classification of Coronaviruses
“Coronavirus” is an umbrella term for the entire family Coronaviridae, not a single pathogen. This family is part of a larger taxonomic order known as Nidovirales. All members share the signature crown-like morphology, which is the basis for the group’s name.
The family Coronaviridae is subdivided into four main genera: Alpha, Beta, Gamma, and Delta coronaviruses. The Alpha and Beta genera primarily contain viruses that infect mammals, including humans. Examples of human coronaviruses (HCoVs) that cause mild common colds are HCoV-229E (an Alphacoronavirus) and HCoV-OC43 (a Betacoronavirus). The Gamma and Delta genera include viruses that infect birds and fish.
Distinguishing the Virus Name from the Disease Name
A common point of confusion is the difference between the name of the virus and the name of the disease it causes. In virology, these two entities are named by different international bodies and follow different conventions. The virus is the biological agent, while the disease is the set of symptoms and pathology resulting from the infection.
For the recent global outbreak, the specific virus is named Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). This name was assigned by the International Committee on Taxonomy of Viruses (ICTV) based on its genetic structure and relation to the original SARS virus. The illness caused by this pathogen is named COVID-19, a designation given by the World Health Organization (WHO). This naming pattern holds for earlier outbreaks, such as the virus SARS-CoV causing the disease SARS, and MERS-CoV causing MERS.