Understanding the Range of Reactions to SARS-CoV-2

What you need to know

Two years into the COVID-19 pandemic, it is still challenging to predict how a person will respond to SARS-CoV-2, the virus that causes COVID-19. Outcomes can range from a person who is asymptomatic, or who shows no signs of infection, to someone developing symptoms so severe they lead to death. In a study funded by the National Institute of Allergy and Infectious Diseases, researchers are using mice to create models that mimic the range of reactions to SARS-CoV-2 infection seen in people.

What did the researchers do?

Geneticist Mark Heise, Ph.D., and his colleagues at the University of North Carolina, Chapel Hill, are using different types, or strains, of genetically diverse mice and studying their response to SARS-CoV-2 infection.

“We measure whether the virus can infect each mouse strain, whether it causes disease, and what the disease course looks like,” Heise said. Some strains get infected but do not develop any signs of COVID-19 at all. “Those strains might be analogous to the asymptomatic infections that we see in humans,” Heise explained.

The group’s next goal is to identify the mouse genes that account for these differences in symptoms. Once the genes are identified, researchers can determine whether the same genes are responsible for symptom differences in humans such as the loss of the sense of smell — a symptom that is less common with the Delta and Omicron variants. “Do some strains of mice lose their sense of smell — and if so, is this under genetic control? We want to know if we can use the mouse strains to really understand what’s happening in people.”

Why is this research important?

According to Heise, the emergence of the Omicron variant in late 2021 illustrated the pressing need to develop new therapies for COVID-19 and to understand genetic resistance and susceptibility to the virus. “[Understanding the range of outcomes] will help us identify who is at the highest risk of poor outcomes so we can treat those people more quickly.”

Where can I go to learn more?

Decoding the Genetics Behind COVID-19 Infection

• NIH-supported researchers are also looking at the range of COVID-19 outcomes in people, hoping to find clues to the underlying genetics that can be more closely studied.

Understanding Long-Term Outcomes

• NIH has put together a cohort made up of thousands of people to study the long-term impact of COVID-19 on people.

Sources

Sarkar, S., & Heise, M. T. (2019). Mouse models as resources for studying infectious diseases. Clinical Therapeutics, 41(10), 1912–1922. https://doi.org/10.1016/j.clinthera.2019.08.010