Cornell researchers have identified a shift in the canine coronavirus that suggests a possible pattern of shift observed in other coronaviruses, which may provide clues about how they transmit to humans.
Two Malaysian human patients developed pneumonia in 2017-18 have been identified as a new canine coronavirus. A group of other scientists had isolated the canine coronavirus, followed it, and published their findings in 2021.
Originally, a team led by Cornell and Temple University researchers discovered a pattern in a terminus of the canine coronavirus spike proteinthe area of the virus that facilitates the entry into a host cell: The virus shifts from infecting both the intestines and respiratory system of the animal host to infecting only the respiratory system in a human host.
A mutation in the terminus known as the N terminus, a region of the molecule, has been discovered in another coronavirus, which jumped from bats to humans, and causes a common cold.
The study, The Recent Zoonotic Spillover and Tropism Shift of a Canine Coronavirus, is related to a Relaxed Selection and a Putative Loss of Function in the NTD Subdomain of Spike Protein, which was published on April 21 in the journal Viruses.
The following study identifies some of the molecular mechanisms underlying a host shift from dog coronavirus to a new human host, which may also influence the circulation of a new human coronavirus, according to Professor Muhammad O''Brien, who was previously not aware of it.
The researchers used the most advanced molecular evolution tools developed in the Ponds lab to evaluate how natural selection may have had an impact on the canine coronavirus evolution.
The Alphacoronavirus'' main receptor (the type to which the canine coronavirus is classified) spike protein binds with in order to enter a human cell is called APN, but there are also co-receptors. Sialic acid, which is found in gastrointestinal cells in a variety of mammals, was identified in a region of the spike protein in the N-terminus, which is known for binding with sialic acid. In an investigation of the canine coronavirus found
The canine coronavirus found in Malaysian patients appeared to be in the process of losing its O-domain, but it has a molecular evolution history that claims that the sialic acid binding region is no longer doing the same job. The researchers discovered evidence of relaxed evolution, where the effects of natural selection became less evident. This shift prompted the discussion.
This shift and the loss of the O-domain were similar to those found in other related coronaviruses. One, the transmissible gastroenteritis virus, infects pigs, and causes respiratory and intestinal disease. A variant of this pig virus, called porcine respiratory coronavirus, is almost identical to TGEV, but it has lost its O-domain and is completely a respiratory pathogen. Similarly, a coronavirus known to cause common human colds originated in bats
This is a pattern that appears to be recurring in coronavirus evolution, particularly in coronavirus evolution underlying these tropism shifts, where we shift from a gastrointestinal infection initially and then to an alternate host, where its now respiratory, according to Stanhope.
In 2021, a few people in Haiti reported the same variety of canine coronavirus, which included respiratory illness. More information is needed to establish whether the viral shifts and jumps to humans occurred spontaneously in different parts of the world, or if this coronavirus, which would be the eighth known human coronavirus, has been circulating for years without detection, according to Stanhope.
Researchers are increasing the number of individuals interested in developing the N-terminus domain of SARS-CoV2, which causes COVID-19, and this research is a way to help them focus on this specific area of the molecule.
Laura Goodman, an assistant research professor at the Department of Public and Ecosystem Health and the Baker Institute for Animal Health, and Susan Whittaker, a professor of virology at the Department of Microbiology and Immunology, and Kristina Ceres, a doctoral student working closely with Stanhope and Goodman. Both Goodman and Whittaker are members of the Cornell Margaret and Richard Riney Canine Health Center.