New variants of SARS-CoV-2 can develop when animals contract COVID-19 from humans. To study this phenomenon, an interdisciplinary team from the College of Veterinary Medicine and Biomedical Sciences systematically analyzed variations that can be found in the virus after infection of cats, dogs ferrets, hamsters, and other animals.
Confirmed COVID-19 cases in different wild, zoo and household animals demonstrate cross-species transmission, which is a rare occurrence for most viruses.
SARS-CoV-2, which is a member of coronaviruses, has a very broad species range. Generally speaking, a variety of viruses don’t have the ability to infect other species of animal and evolved to be very specific.”
Laura Bashor, one of the first authors and a doctoral student, Department of Microbiology, Immunology and Pathology
Erick Gagne, who was the original author and is now an assistant professor of wildlife ecology at the University of Pennsylvania, said that humans have been exposed to numerous animals that this virus could spread to a variety of species.
Researchers have the unique opportunity to study the evolution of SARS CoV-2 throughout the global spread and reach of the virus. This includes in the laboratory of University Professor Distinguished Sue VandeWoude at Colorado State University.
These specialists in disease transmission in domestic and wild cats applied their experience in the field of sequence analysis, and also studying a collection of genomes to SARS-CoV-2. The study was published in PNAS, the official journal of the National Academy of Sciences.
Emerging mutations
Researchers from the VandeWoude lab collaborated with Assistant Professor Angela Bsco-Lauth in the Department of Biomedical Sciences. They utilized their experience in animal modeling to develop an instrument that can detect SARS-CoV-2 susceptibility in animal species.
The findings were also enabled by a more recent sequencer that enabled the identification of genetic variants in the human population in different stages of the study. Associate professor Mark Stenglein in the Department of Microbiology, Immunology, and Pathology provided computational skills for the analysis of biological molecule sequences. This is also called bioinformatics.
Bashor said, “We discovered there was evolution, selection, and evolution on the virus and we saw several more variants emerge in its genome sequence.”
Bosco-Lauth and Bowen created sufficient viral material to aid in the study by growing a SARS-CoV-2 virus-infected human sample in laboratory-grown cells. Bashor and Gagne determined that multiple mutations developed and became a greater percentage of the genetic population at each step of this process.
Then the virus was introduced to the four species of household and the virus samples were collected from their nasal passages following infection.
Gagne said that “in the animals, cell culture variants returned to the human form, which suggests that there could be a process of adaptation occurring in the cell culture and environment that were selected for those variants.”
These mutations are not all present in the cell culture SARS-CoV-2 variant are transferred to the new hosts. However, several mutations were discovered in the virus shed by the live animals.
In the beginning of 2020, the initial viral sample was isolated. The study revealed that mutations have been detected in the human population, which resulted in widespread SARS-CoV-2 strains.
Dr. Sue VandeWoude, senior researcher Dr. Sue VandeWoude, a senior researcher, said, “Among those were some which we’ve seen in humans, in the beta, delta, and.” “There were genetic code modifications that mirrored the findings of other researchers in humans.”
Contact exposure between two cats proved the SARS-CoV-2 variant is transmitted, possibly creating a new strain within the species.
Bosco-Lauth explained, “That’s what’s happening in people as well.” “Hosts that have been modified to help fight SARS/CoV-2 are also adept at allowing these mutations stick and to be passed on.”
The future
Bashor did not expect to study SARS-CoV-2 when she came to CSU to start her doctoral studies during the outbreak. But, it gave her an opportunity to start her career as a graduate student on a “really cool and viable project” in disease ecology and evolution.
Gagne was finishing his postdoctoral study on cross-species transmission of feline retroviruses in the VandeWoude lab when the team started the study of SARS-CoV-2. He is now an assistant professor and continues to study the SARS-CoV-2 spillover at the University of Pennsylvania.
Graduate students and early career scientists, such as Bashor and Gagne, have made meaningful contributions to SARS-CoV-2 research, said VandeWoude.
The team continued to investigate cats because they are more vulnerable to COVID-19 spillovers from human beings and could spread the virus to other cats.
Bashor began to analyze SARS-CoV-2 genome sequences derived from an array of cat species across the world, including tigers, snow leopards and lions. The publically available information of cats infected with the virus could provide additional insights on the ability to adapt and change COVID-19 in and between cat species.
There is no evidence of transmission between cats and humans. However, cats remain susceptible to all COVID-19 variants found in the human population.
The research team may be able to answer the question, “What is the future for SARS-CoV-2 in humans and animals?” by understanding viral evolution in cats.
Bashor, L., et al. (2021) SARS-CoV-2 evolution in animals suggests mechanisms for rapid selection of variants. PNAS. doi.org/10.1073/pnas.2105253118.
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