US researchers are hopeful that research on Covid-19 can be greatly improved, using an existing strain of lab mouse that is highly susceptible to the disease.

Laboratory mice used in Covid-19 studies must often be genetically modified so that they better reflect what happens in human infection, but a strain called CAST/EiJ, derived from wild mice, which are already bred at EARA member, The Jackson Laboratory (JAX), have now been identified that do not need to be further genetically modified to study the disease.

CAST mice are genetically ‘clean’, making them as close to the natural mouse genome as possible. This makes them suitable for studying Covid-19 in a way that is more relevant to the human condition as the mice have more genetic diversity that better reflects real life.

Researchers at JAX, in Bar Harbor, Maine, and the Trudeau Institute, in Saranac Lake, New York, found that CAST mice developed severe (or acute) Covid-19 after infection, such as more severe lung damage, compared to the other strains that only had mild symptoms.

It is hoped that this strain will now be an important tool in developing Covid-19 vaccines as new coronavirus variants emerge.

Nadia Rosenthal, at JAX, said: “CAST mice stand poised to transform Covid-19 research and prepare us for future challenges. Equally important, the work reinforces the critical role of genetic diversity in science.”