University of California, Davis: Understanding the Evolution of SARS and Coronavirus Viruses

As COVID-19 dominates the world, related viruses circulate quietly among wildlife. New studies show how SARS-CoV-2, the virus that causes COVID-19, and SARS-CoV-1, which caused the outbreak of SARS in 2003, are interrelated. This study, recently published in the journal Virus Evolution, better describes the evolution of these viruses, how they have acquired the ability to infect humans, and which other viruses are ready for human spillover. It will help you to understand it well.

“How did these viruses become today? Why do some of them have the ability to infect humans, but others do not?” California Simon Anthony, an associate professor of pathology, microbiology and immunology at the University of California, Davis, and lead author of the paper, said.

According to Anthony, both SARS-CoV-1 and SARS-CoV-2 belong to a group called the salbecovirus, but they are actually quite different. Scientists have divided the salbecovirus into five strains, SARS-CoV-1 belongs to strain 1, and SARS-CoV-2 belongs to strain 5.

Although these two viruses belong to different strains, they both use the ACE2 receptor to invade human cells.

“That’s amazing, because there are other viruses that are more closely related to SARS-CoV-1 that do not use ACE2, so how SARS-CoV-1 is similar to the more distantly related virus. Did you come to do it ?? “

Family tree of the virus

Columbia University graduate students Anthony and Heather Wells have created a family tree of all SARS-like viruses. They found that strain 5, including SARS-CoV-2, was an ancestral strain. They concluded that most of the strain 1 viruses associated with SARS-CoV-1 lost their ability to use the human ACE2 receptor long ago due to genomic deletions. However, SARS-CoV-1 and several other viruses have regained the ability to use human ACE2 at some point.

It probably happened through a process called recombination, Wells said. To do this, two different viruses need to infect the same animal at the same time, producing a hybrid virus that has the ability to infect humans via ACE2.

Family trees also provide insight into the geographic origin of these viruses, Wells said. So far, all viruses that use ACE2 have been detected in Yunnan, indicating that SARS-CoV-2 occurred elsewhere in China rather than in Wuhan, where the first case of COVID-19 was reported. Means

One of the unanswered questions is why SARS-CoV-2 is now emerging. If this virus had always targeted ACE2, it could have long been capable of infecting humans. So why did it appear at this time?

“Other factors need to be involved,” Anthony said. “Having the genetic ability to infect humans is only part of the story.”

The study provides an evolutionary background on why these viruses behave that way, Anthony said. This allows researchers to place newly discovered viruses in their family tree and estimate whether they can infect humans.

“We know that the genetic potential for spillover does not mean that it will happen. However, it is important to identify high-risk viruses. Use epidemiological or ecological studies. You can then investigate how and how people come into contact with bats and other animals that carry these viruses. “

“It also reminds us that there are many viruses that need to be better understood, not just SARS-CoV-1 and 2,” he said.

Additional co-authors for this study are: TracyGoldstein, Christine Kreuder Johnson, Jonna Mazet, Michael Cranfield, Kirsten Gilardi, One Health Institute, Karen C. Drayer Wildlife Health Center, UC Davis School of Veterinary Medicine; Benard Ssebide and Julius Nziza, Gorilla Doctors and Mountain Gorilla Veterinary Project; Washington State University, Pullman, Washington; Michael Letko, and Maria Diuk-Wasser, National Institute of Allergy and Infectious Diseases, NIH, Hamilton, Montana Virology Institute. Gorcarasso, Albert Einstein Medical College, New York; Denis Byarugaba, Makerere University, Kampala, Uganda; Isamara Navarrete-Macias and Eliza Liang, Columbia University; Barbara Han, Cary Ecosystem Institute, Milbrook, New York; University of California, Los Angeles Morgan Tingley.

This work was supported by a grant from NIH and USAID through the PREDICT project.

This press release was created by University of California, Davis.. The views expressed here are those of the author himself.