Home Biomedical research Researchers say viral evolution in animals could reveal future of COVID-19

Researchers say viral evolution in animals could reveal future of COVID-19



The results of a new study suggest that when animals catch COVID-19 from humans, new variants of SARS-CoV-2 may appear. To assess this phenomenon, an interdisciplinary team from the College of Veterinary Medicine and Biomedical Sciences systematically analyzed the types of mutations occurring in the virus after infection of 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 demonstrate interspecific transmission, which is rare for most viruses. “SARS-CoV-2, in the area of ​​coronaviruses, has a very wide range of species,” said Laura Bashor, one of the first authors and a doctoral candidate in the Department of Microbiology, Immunology and Pathology. “Generally speaking, many types of viruses cannot infect other species of animals, they have evolved to be very specific.”

“Humans have so much exposure to many different animals that has made it possible for this virus to have the ability to expose a variety of different species,” said Erick Gagne, lead author and now assistant professor of ecology. wildlife diseases at the University of Pennsylvania. The global reach and spillover of the virus has given researchers a unique opportunity to study the viral evolution of SARS-CoV-2, including in the lab of distinguished professor Sue VandeWoude at Colorado State University.

These specialists in disease transmission in wild and domestic cats have applied their experience in sequence analysis and the study of a collection of genomes to SARS-CoV-2. Researchers from the VandeWoude lab worked with Assistant Professor Angela Bosco-Lauth and Professor Dick Bowen from the Department of Biomedical Sciences, who used their expertise in animal modeling to develop a SARS-CoV-2 susceptibility test in animal species. In addition, the key to the results was a new technique for sequencing the virus at different stages of the study, now common for detecting variants in the human population. Mark Stenglein, associate professor in the Department of Microbiology, Immunology and Pathology, provided computational skills in the analysis of the sequences of biological molecules, known as bioinformatics, under study.

“We found that there was evolution, we saw the selection on the virus and we saw a lot of variants emerging in the virus genome sequence,” Bashor said. To provide enough viral material for the study, Bosco-Lauth and Bowen grew a human sample of SARS-CoV-2 in cells grown in the laboratory. Bashor and Gagné determined that multiple mutations developed and became a greater percentage of the genetic population, at each stage of this process.

Then the virus was introduced into the four domestic species and samples of the virus were taken from their nasal passages after infection. “In animals, the cell culture variants have reverted to the original human type, indicating that there is likely adaptation occurring in this cell culture and the environment that was selected for these variants,” said Won.

Not all of these mutations within the SARS-CoV-2 variant in cell culture are transferred to the new hosts. Instead, different mutations emerged within the virus shed by living animals. The initial viral sample for the study was isolated in early 2020. The team observed mutations that have since formed widespread strains of SARS-CoV-2 in the human population at an accelerated rate throughout the study period. ‘study.

“Of these, there were a number that we have since seen in humans in alpha, beta and delta variants,” said lead author Dr Sue VandeWoude. “There have been specific changes in the genetic code that mimic what other scientists have reported in humans.” Contact exposure between two cats has demonstrated that the SARS-CoV-2 variant can be transmitted with the possibility of producing a new strain within the species.

“This is what we see in people too,” said Bosco-Lauth. “Hosts that are really well suited to endure SARS-CoV-2 infection are also very good at allowing these mutations to hook up and be passed on.” Bashor had not planned to study SARS-CoV-2 when she came to CSU to begin her doctoral studies during the pandemic. However, it provided a unique opportunity to embark as a graduate student on a “really cool and viable project” in the ecology and evolution of disease.

Gagné was completing his postdoctoral research on the interspecific transmission of feline retroviruses in the VandeWoude laboratory when the team launched the SARS-CoV-2 study. Now an assistant professor, he continued to investigate the fallout from SARS-CoV-2 with the Wildlife Futures Program at the University of Pennsylvania. Graduate students and early-career scientists like Bashor and Gagné have made significant contributions to SARS-CoV-2 research, said Vande Woude.

The team continued their investigations to focus on cats, as they have shown greater sensitivity to COVID-19 fallout from humans and can produce variants of the virus and spread to other cats. Bashor has started analyzing the SARS-CoV-2 genome sequences of a large number of cat species around the world, including tigers, lions and snow leopards. Publicly available data on infected cats could provide additional information on the adaptability and mutability of COVID-19 within and between species of cats.

There is no evidence of cat-to-human transmission. But cats remain susceptible to all variants of COVID-19 in the human population. By understanding viral evolution in cats, the research team can find answers to the question: what is the future of SARS-CoV-2 for humans and animals. (ANI)

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