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.[citation needed] 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. It was easily transmitted through direct contact between chickens or experimental transfer of the bronchial exudates from infected to healthy chickens. Maximum mortality recorded was 90%.

The causative pathogen was not known. 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 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). 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. (Beach had discovered infectious laryngotracheitis virus in 1931. They concluded that:

It was found that chickens that recovered from an infection with one of the two strains of virus were refractory to further infection with either strain. It was also found that the sera from chickens that have recovered from an infection with one strain of the virus would neutralize virus of either strain. These results show the identity of the two strains of virus.

Chickens refractory to infection with this virus were shown to be susceptible to the virus of laryngotracheitis. Likewise, chickens refractory to the latter virus were susceptible to the former. These results demonstrate that the two viruses are distinct from one another.

Hudson and Beaudette later in 1937 were able to culture IBV for the first time using chicken embryos. This specimen, known as the Beaudette strain, became the first coronavirus to have its genome completely sequenced in 1987.

Regards,
Ann Jose

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