Coronaviruses were first discovered in the 60s of the 20th century from the nasal cavity of patients with the common cold. It is a genus of viruses in the subfamily Coronaviaceae of the family Coronaviaceae. Coronavirus is an enveloped virus with a positive-sense single-stranded RNA genome and a helix-symmetric nucleocapsid. Coronaviruses have genome sizes ranging from about 26 to 32 thousand bases, with RNA viruses being the largest.

The word "coronavirus" derives from the Latin corona, meaning crown or halo, and refers to the characteristic appearance of virions (the infectious form of the virus) under an electron microscope, edged by huge spherical surface protrusions that form an image reminiscent of a crown or corona. This morphology is formed by viral spike proteins, which form on the surface of the virus and determine host predisposition.

Diseases caused by coronavirus

Coronaviruses mainly infect the upper respiratory tract and gastrointestinal tract of mammals and birds. Seven coronaviruses are known to infect humans. A large percentage of all common colds in adults and children are caused by coronaviruses. Coronaviruses cause colds, the main symptoms are fever, swollen throat, adenoids, mainly in winter and early spring. Coronaviruses can cause pneumonia, or direct viral pneumonia, or secondary bacterial pneumonia, as well as bronchitis, direct viral bronchitis, or secondary bacterial bronchitis. The SARS coronavirus, discovered in 2003, causes severe acute respiratory syndrome. Coronaviruses cause infections of the upper and lower respiratory tracts. Unlike rhinovirus, another common cold virus, human coronaviruses are difficult to grow in a laboratory.

Coronaviruses also cause a range of illnesses in farm animals and domestic pets, some of which can be severe and pose a threat to agriculture. Infectious bronchitis virus (IBV) in chickens is a coronavirus that targets not only the respiratory tract but also the genitourinary tract. Livestock coronaviruses include swine coronaviruses (infectious gastroenteritis coronavirus, TGE) and bovine coronaviruses, both of which cause diarrhea in young animals. Feline intestinal coronaviruses can cause infectious peritonitis in felines. There are two types of coronaviruses that infect ferrets: ferret enteric coronaviruses, which cause mild gastrointestinal illness, and ferret systemic coronaviruses (FSCs), which cause more lethal respiratory diseases. Mouse hepatitis virus (MHV) is also a coronavirus that causes an epidemic mouse disease with a high mortality rate.

The infection cycle of the coronavirus

Coronaviruses contain a strand of RNA inside their envelope that cannot multiply without entering a living cell and with the help of a replication machine inside the cell. The spikes on the outer shell of the virus provide an entry point for them to invade the cells and help them bind to the cells. Once inside the cell, they turn the cell into a virus factory, using their molecular conveyor belts to produce more virus for release. The new virus infects another cell, and the cycle begins again.

Types of human coronaviruses

Pick up the eighteen generations of the ancestors of the new coronavirus, and reveal its true source and whereabouts

For years, scientists knew only two human coronaviruses (HCoV-229E and HCoV-OC43). With the high-profile publicity of the SARS epidemic, virologists have renewed interest in coronaviruses.

By the end of 2004, three independent research laboratories had reported the discovery of a fourth human coronavirus. Different research groups have named it NL63, NL and the New Haven coronavirus.

In early 2005, a team of researchers at ** University reported the discovery of a fifth person coronavirus among two patients with pneumonia. They named it the human coronavirus HKU1.

The source of the 2019-20 Chinese pneumonia outbreak in Wuhan was a novel coronavirus, which the WHO labeled as 2019

CoV。

So to sum up, there are currently seven known human coronaviruses: human coronavirus 229E, human coronavirus OC43, SARS coronavirus, human coronavirus NL63 (HCoV-NL63, New Haven coronavirus), human coronavirus HKU1, Middle East respiratory syndrome coronavirus (MERS-CoV), and Wuhan coronavirus (2019).

CoV), also known as the novel coronavirus.

Types of animal coronaviruses

Pick up the eighteen generations of the ancestors of the new coronavirus, and reveal its true source and whereabouts

Coronaviruses have been recognized as the main causative agent causing veterinary diseases since the early 70s of the 20th century, and with the exception of avian infectious bronchitis, the main diseases associated with coronaviruses occur mainly in the intestines. Major animal coronaviruses include:

Infectious bronchitis virus (IBV) causes infectious bronchitis in chickens.

Porcine coronavirus (porcine infectious gastroenteritis coronavirus, TGEV).

Bovine coronavirus (BCV) causes severe polyenteritis in young calves.

Feline coronaviruses (FCoV) cause mild enteritis in cats and severe infectious peritonitis in cats.

Two canine coronaviruses (one causes enteritis and the other is seen in respiratory diseases).

Turkey coronavirus (TCV) causes turkey enteritis.

Ferret intestinal coronaviruses cause ferret epidemic catarrhal enteritis.

Ferret systemic coronaviruses cause ferret FIP syndrome

Pantropical canine coronavirus.

Porcine epidemic diarrhea virus (PED or PEDV) causes a high level of piglet death.

Evolution of coronavirus

Pick up the eighteen generations of the ancestors of the new coronavirus, and reveal its true source and whereabouts

The latest common ancestor of the coronavirus is thought to be around 8000 BC. Bats and birds are warm-blooded flying vertebrates that are ideal hosts for coronavirus gene sources, bats are gene sources for α coronaviruses and β coronaviruses, and birds are gene sources for gamma coronaviruses and triangular coronaviruses that power the evolution and spread of coronaviruses.

Bovine coronaviruses and canine respiratory coronaviruses were isolated from the same ancestor in 1951. The bovine coronavirus and the human coronavirus OC43 were separated in 1899. Bovine coronaviruses were isolated from equine coronaviruses at the end of the 18th century.

The MRCA of the human coronavirus OC43 dates back to the 50s of the 20th century.

MERS-CoV, although related to several species of bats, differentiated from these viruses centuries ago.

The most closely related bat coronaviruses and SARS coronaviruses were isolated in 1986.

The alpaca coronavirus and the human coronavirus 229E mutated before 1960.

The human coronaviruses NL63 and bat coronaviruses shared an MRCA between 563 and 822 years ago.