A fungus devastating frogs and toads on nearly every continent may have an Achilles heel. Scientists have discovered a virus that infects the fungus, and that could be engineered to save the amphibians.

The UC Riverside researchers who found the virus are excited about the implications of their discovery. In addition to helping them learn about how fungal pathogens rise and spread, it offers the hope of ending what they call a global amphibian pandemic.

Additionally, the virus that infects Bd was hard to find because most known viruses that infect fungi, called mycoviruses, are RNA viruses. However, this virus is a single-stranded DNA virus. By studying the DNA, the researchers could see the virus stuck in the genome of the fungus.

It appears that only some strains of the fungus have the virus in their genome. But the infected ones seem to behave differently than the ones that don’t. “When these strains possess the virus they produce fewer spores, so it spreads more slowly. But they also might become more virulent, killing frogs faster,” Stajich said.

Right now, the virus is essentially trapped inside the fungal genome. The researchers would eventually like to clone the virus and see if a manually infected strain of Bd also produces fewer spores.

“Because some strains of the fungus are infected and some are not, this underscores the importance of studying multiple strains of a fungal species,” Yacoub said.

Moving forward, the researchers are looking for insights into the ways that the virus operates. “We don’t know how the virus infects the fungus, how it gets into the cells,” Yacoub said. “If we’re going to engineer the virus to help amphibians, we need answers to questions like these.”

In some places, it appears there are a few amphibian species acquiring resistance to Bd.

“Like with COVID, there is a slow buildup of immunity. We are hoping to assist nature in taking its course,” Yacoub said.