A new clue reveals how the dog coronavirus sneaks into the human immune system

It comes with a protein shift.
Derya Ozdemir

A team of Cornell and Temple University researchers has discovered a change in canine coronavirus that may give insight into how it spreads from animals to humans.

The study goes back to 2017 and 2018 when a new canine coronavirus was first detected in two Malaysian human patients. Another team of scientists isolated and sequenced the new canine coronavirus, releasing their findings in 2021, three years later.

A team has now discovered that the virus goes through a transition when it jumps from dogs to humans. The researchers identified a pattern that occurs in the terminus of the canine coronavirus spike protein, which is the part of the virus that allows it to gain entry into cells.

According to the study published in the journal Viruses, the canine coronavirus shifts from infecting both the intestines and respiratory system of the animal to infecting only the respiratory system in a human. 

Identifying the underlying molecular mechanisms

Canine coronavirus is a highly contagious viral illness that affects dogs all over the world. It's important to highlight that it's very different from the human coronavirus that caused the COVID-19 pandemic. Canine coronavirus commonly causes mild or difficult-to-detect symptoms; however, it can be fatal in certain circumstances. 

The new canine coronavirus actually made the jump pre-COVID. In 2021, the same canine coronavirus strain discovered in Malaysia was also detected in a few cases in Haiti, who also had respiratory illness. Canine coronaviruses aren’t generally thought to infect humans, which is why it came as a surprise.  

The researchers employed cutting-edge molecular evolution methods to study how natural selection forces may have impacted the development of the canine coronavirus, and discovered signs of "relaxed evolution," in which natural selection forces were decreased, allowing the shift to occur.

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"This study identifies some of the molecular mechanisms underlying a host shift from dog coronavirus to a new human host, that may also be important in the circulation of a new human coronavirus that we previously didn’t know about," said study co-author Michael Stanhope, professor of public and ecosystem health in the College of Veterinary Medicine, in a press release

More research is needed to determine if the viral changes and leaps to humans occurred spontaneously in different regions of the world. Stanhope further indicated that additional studies might show if this coronavirus has been circulating in the human population for many decades without being detected.

This is another instance that shows that coronavirus outbreaks aren't rare, which is why humans can expect a new one to pop up and jump from animals to people from time to time. Studies also show how animals relocating due to climate change could be the trigger for the next pandemic. Consequently, Bill Gates, the Microsoft founder turned philanthropist, urged for the formation of a worldwide response team to monitor diseases that might usher in the next pandemic. 

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