Researchers say viral evolution among animals might reveal COVID-19’s future

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The results of a new study suggest that when animals catch COVID-19 from humans, new variants of SARS-CoV-2 can emerge. To assess this phenomenon, an interdisciplinary team in the College of Veterinary Medicine and Biomedical Sciences systematically analyzed the types of mutations that occur in the virus after infecting cats, dogs, ferrets, and hamsters. The study was recently published in “PNAS,” the official journal of the National Academy of Sciences.

Confirmed cases of COVID-19 in a variety of wild, zoo and domestic animals show cross-species transmission, which is rare for most viruses. “SARS-CoV-2, in the coronavirus world, has a very wide range of species,” said Laura Bashore, one of the first authors and a doctoral student in the Department of Microbiology, Immunology and Pathology. “In general, many types of viruses cannot infect other types of animals, they have evolved to be very specific.”

“Humans are frequently exposed to many different animals which has afforded this virus the opportunity to expose a variety of different species,” said Eric Jani, first author and associate professor of wildlife disease ecology at the University of Pennsylvania. The global spread and spread of the virus has provided researchers with a unique opportunity to investigate the viral evolution of SARS-CoV-2, including in the laboratory of Distinguished University Professor Sue Fandyod at Colorado State University.

These disease transmission specialists in wild and domestic cats have applied their expertise in sequence analysis and genome assembly study to SARS-CoV-2. Researchers in VandeWoude’s lab worked with Associate Professor Angela Bosco-Lauth and Professor Dick Bowen in the Department of Biomedical Sciences, who used their expertise in animal modeling to develop a SARS-CoV-2 susceptibility test for animal species. Also, key to the results was a newer sequencing technology for the virus at various stages of the study, which is now popular for detecting variants in humans. Mark Stenglin, associate professor in the Department of Microbiology, Immunology and Pathology, provided computational skills in analyzing the sequences of biological molecules, known as bioinformatics, for the study.

“We found that there was an evolution, we saw selection on the virus, and we saw a lot of variants appearing in the genome sequence of the virus,” Bashur said. To provide ample viral material for the study, Bosco-Luth and Bowen transplanted a human sample of SARS-CoV-2 into cells grown in the laboratory. Bashor and Gagne determined that multiple mutations evolved, becoming a larger percentage of the genetic population, at each step of the process.

The virus was then introduced to the four domestic species, and virus samples were collected from their nasal passages after infection. “In animals, the cell culture variants reverted back to the initial human type, suggesting that adaptation may have occurred in that cell culture and the environment in which those variants were chosen,” Jani said.

Not all of these mutations were transferred within the SARS-CoV-2 cell culture variant in the new hosts. Instead, various mutations appeared within the virus shed by live animals. The study’s initial viral sample was isolated in early 2020. The team observed mutations that have since formed the SARS-CoV-2 strains that are widespread in humans at an accelerating rate throughout the study period.

“Among these are a number we’ve since seen in humans in alpha, beta and delta variants,” said lead author Dr. Sue Vande Wood. “There were specific changes in the genetic code that mimic what other scientists have reported in humans.” Contact exposure between two cats showed that the SARS-CoV-2 variant can be transmitted with the potential to produce a new strain within the species.

“That’s what we see in people, too,” said Bosco Louth. “Hosts that are well-adapted to support SARS-CoV-2 infection are also very good at allowing these mutants to survive and transmit.” Bashur did not expect to study SARS-CoV-2 when she came to CSU to begin her doctoral studies during the pandemic. However, it did provide a unique opportunity to begin work as a graduate student on a “really great and viable project” in the setting and progression of disease.

Jani was completing his postdoctoral research on cross-species transmission of retroviruses in VandeWoude’s lab when the team launched the SARS-CoV-2 study. Now an assistant professor, he has continued to investigate the spread of SARS-CoV-2 with the Wildlife Futures Program at the University of Pennsylvania. Vande Woude said graduate students and early-career scientists such as Bashor and Gagne, have made useful contributions to SARS-CoV-2 research.

The team continued their investigations to focus on cats, as they have shown a higher susceptibility to spread of COVID-19 than humans and can produce different types of the virus and spread to other cats. Bashur began analyzing the SARS-CoV-2 genome sequence from a large group of cat species around the world, including tigers, lions and snow leopards. Publicly available data for infected cats could provide additional insights into the adaptability and transformation of COVID-19 within and between cat species.

There is no evidence of transmission from cats to humans. But cats are still susceptible to all types of COVID-19 in humans. By understanding viral evolution within cats, the research team may find answers to the question: What is the future of SARS-CoV-2 for humans and animals. (Ani)

(This story has not been edited by the Devdiscourse staff and is automatically generated from a shared feed.)

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