'Russian nesting doll' virus hides inside a deadly fungus, making it even more dangerous to people

Photograph taken of Aspergillus fumigatus under a microscope. The cultures shown on the right are infected with virus, while those on the left are uninfected.

A fungus flagged as a "critical" concern by the World Health Organization may have a secret weapon: a virus hidden inside it.

Now, a new study suggests that targeting this virus may offer a new strategy for treating these dangerous fungal infections in people.