Researchers at Washington University School of Medicine in St. Louis, Missouri, have reported the development of a mouse model of COVID-19 that replicates the illness in people. The model can be easily adopted by other scientists to dramatically accelerate the testing of experimental COVID-19 treatments and preventives.
“There’s been a huge push to develop vaccines and therapeutics as quickly as possible, and since animal models have been limited, these investigational drugs and vaccines have been put directly into humans, and many of them haven’t panned out,” said Principal Investigator Michael S. Diamond, MD, PhD, the Herbert S. Gasser Professor of Medicine and an expert on viral infections. “Mice are useful because you can study a large number of them and observe the course of the disease and the immune response in a way that is hard to do in people. It would be more cost-effective and efficient and safer for people if we could get more information about how these potential drugs and vaccines work and how effective they are before we move to more challenging non-human primate and ultimately human studies.”
In addition to drug and vaccine testing, scientists can use the model with mice bred to develop health conditions such as obesity, diabetes or chronic lung disease to investigate why some people develop life-threatening cases of COVID-19 while others recover on their own.
“The mice develop a similar lung disease to what we see in humans,” said Diamond, who is also a professor of molecular microbiology, and of pathology and immunology. “They get quite sick for a while but eventually recover, like the vast majority of people who get COVID-19. You can use this technique with almost any strain of laboratory mouse to make them susceptible to SARS-CoV-2 and then do whatever kind of study you want: test vaccines or drugs, study the immune response, and many other things related to how the virus causes disease.”
The model also can be used to better understand the factors that put some people at risk of severe COVID-19 disease. Advanced age, male sex, and conditions such as obesity, diabetes, and heart, kidney or lung disease all increase risk of severe COVID-19 for reasons that are not fully understood.
“It would be easy to study, for example, older mice or obese mice and see how they respond to infection,” said Diamond. “I’d expect that they would do substantially worse, but the real question is why. Do they have more virus in the early stages? Is their condition weakening the immune response, or perhaps exacerbating a detrimental inflammatory response? With this model, we can begin to look at some of those factors that are very hard to study in people.”