The history of coronaviruses is an account of the discovery of the diseases caused by coronaviruses and the diseases they cause. It starts with the first report of a new type of upper-respiratory tract disease among chickens in the U.S. state of North Dakota, in 1931. The causative agent was identified as a virus in 1933. By 1936, the disease and the virus were recognised as unique from other viral disease. They became known as infectious bronchitis virus (IBV), but later officially renamed as Avian coronavirus. A new brain disease of mice (murine encephalomyelitis) was discovered in 1947 at Harvard Medical School in Boston. The virus causing the disease was called JHM (after Harvard pathologist John Howard Mueller). Three years later a new mouse hepatitis was reported from the National Institute for Medical Research in London. The causative virus was identified as mouse hepatitis virus (MHV), later renamed Murine coronavirus. In 1961, a virus was obtained from a school boy in Epsom, England, who was suffering from common cold. The sample designated B814 was confirmed as novel virus in 1965. New common cold viruses (assigned 229E) collected from medical students at the University of Chicago were also reported in 1966. Structural analyses of IBV, MHV, B814 and 229E using transmission electron microscopy revealed that they all belong to the same group of viruses. Making a crucial comparison in 1967, June Almeida and David Tyrrell invented the collective name coronavirus, as all those viruses were characterised by solar corona-like projections (called spikes) on their surfaces. Other coronaviruses have been discovered from pigs, dogs, cats, rodents, cows, horses, camels, Beluga whales, birds and bats. As of 2022, 52 species are described. Bats are found to be the richest source of different species of coronaviruses. All coronaviruses originated from a common ancestor about 293 million years ago. Zoonotic species such as Severe acute respiratory syndrome-related coronavirus (SARS-CoV), Middle East respiratory syndrome-related coronavirus (MERS-CoV) and Severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2), a variant of SARS-CoV, emerged during the past two decades and caused the first pandemics of the 21st century.
Discovery of chicken coronavirus
Arthur Frederick Schalk and Merle C. Fawn at the North Dakota Agricultural College were the first to report what was later identified as coronavirus disease in chickens. Their publication in the Journal of the American Veterinary Medical Association in 1931 indicates that there was a new respiratory disease that mostly affected 2-day-old to 3-week-old chickens. They referred to the disease as "an apparently new respiratory disease of baby chicks." The symptoms included severe shortness of breath and physical weakness. The infection was contagious and virulent, easily transmitted through direct contact between chickens or experimental transfer of the bronchial exudates from infected to healthy chickens. The maximum mortality recorded was 90%. The causative pathogen could not be identified. Charles D. Hudson and Fred Robert Beaudette at the New Jersey Agricultural Experiment Station in New Brunswick, New Jersey, put forth a hypothesis in 1932 that virus could be the cause and introduced the name as "virus of the infectious bronchitis." But this was a misattribution because at the time another related disease, known as infectious laryngotracheitis, was reported that exhibited almost similar symptoms but mostly affected adult chickens. As Beaudette later recalled in 1937, the disease he described was infectious layngotracheitis, saying: "Infectious laryngotracheitis is said to be the correct name for this disease rather than infectious bronchitis… Moreover, the gasping symptom ordinarily accepted as typical of the disease is also a prominent symptom in infectious bronchitis (gasping disease, chick bronchitis)." The names infectious bronchitis and infectious laryngotracheitis were till then used synonymously and interchangeably. Unaware of the developments, Leland David Bushnell and Carl Alfred Brandly at the Kansas Agricultural Experiment Station studied a similar case which they called "gasping disease" due to the apparent symptom. They had known the disease since 1928. Their report in 1933 titled "Laryngotracheitis in chicks" published in the Poultry Science indicated a clear distinction of infectious bronchitis from infectious laryngotracheitis (cause by a herpes virus) as the main organ affected was the bronchi. The bronchi infection resulted in severe gasping and swift death due to inability to eat food. It was also found that the pathogens could not be bacteria or protozoans as they passed through membranes (Berkefield filter) that would block those pathogens. The isolation and identification of the pathogen as a virus was reported as:
In several experiments we have reproduced the disease in chicks by the intratracheal, subcutaneous and intraperitoneal injection of Berkefeld filtered material. The chicks developed typical gasping symptoms after various periods of incubation, different groups of chicks first showing symptoms in six, seventeen, nineteen, etc., days after receiving the filtrate... The disease may also be transferred by means of filtrates of spleen, liver, and kidney tissues and by the transfer of bacteriologically sterile blood. This was the discovery of infectious bronchitis virus (IBV), the first coronavirus. But Bushnell and Brandy made an erroneous remark by saying, "The symptoms and lesions in the chicks [caused by IBV] are similar to those seen in so-called laryngotracheitis of adult birds and are probably due to the same agent." In 1936, Jerry Raymond Beach and Oscar William Schalm at the University of California, Berkeley, reexamined Bushnell and Brady's experiment with a conclusion that infectious laryngotracheitis and infectious bronchitis with their causative viruses were different. (In 1931, Beach had discovered the virus of infectious laryngotracheitis, now called Gallid alphaherpesvirus 1.) They concluded that:
… excerpt ends here. Continue reading the full article.
