‘Common thread’ may save rare frogs

Researchers have discovered that rare golden frogs that have survived exposure to a deadly fungal disease have a skin microbe in common. Photo courtesy of Brian Gratwicke/Smithsonian Conservation Biology Institute, Front Royal.

A rare breed of golden Panamanian frog has survived exposure to a deadly fungal disease known as chytridiomycosis, according to research from the Smithsonian Conservation Biology Institute in Front Royal.

The findings of this research study were published last week in “Proceedings of the Royal Society,” an internationally renowned, peer-reviewed science journal based in the United Kingdom.

Smithsonian researcher and Panama Amphibian Rescue and Conservation Project Director Brian Gratwicke said the result represents an “intriguing observation and an incremental step” for amphibian-chytrid research.

“It’s the first time we’ve ever had golden frogs survive chytrid exposure,” he said, “We thought they were a species that was 100 percent susceptible.”

According to the online amphibian database “http://www.AmphibiaWeb.com” target=”_blank”>AmphibiaWeb.com, the chytrid fungus is “an emerging infectious disease of amphibians caused by an aquatic fungal pathogen.”

Of the frogs tested, 25 percent survived the exposure and, according to Gratwicke, the frogs that survived all “shared a common thread.”

More specifically, the frogs shared a “community of microbes” that differed from the frogs that died from the exposure.

The discovery was made by Virginia Tech graduate student Matthew Becker, who is a fellow at the Front Royal facility as well as on the study’s 10 co-authors.

Gratwicke said researchers are unsure at the moment if the microbes are what helped the 25 percent survive. “All we can say is that there was an association between these of kinds bacteria and their survival.”

This  common thread  was an unintended observation of the experiment Gratwicke and researchers were conducting.

Researchers were testing an antifungal probiotic treatment — also called beneficial bacteria — technique on the frogs to see if it could help prevent chytrid infection.

The treatments Gratwicke and his team were using, however, did not help the frogs survive.

Gratwicke explained that frogs in the control group (no probiotics) died “at the same rate” as the frogs receiving the probiotic treatments in the experimental groups.

“Initially, it was like ‘Oh my goodness, our experiment failed,” Gratwicke said, noting that they were “very puzzled” regarding the fact that some of the frogs survived across all of the groups.

The frogs that survived, Gratwicke said, “Had gotten chytrid, had become infected and cleared infection. That’s what we want to happen in the wild.”

At the moment, Gratwicke said researchers are unsure what the correlation or the finding means for golden frogs — or even if the survivor frogs are immune to chytrid.

Gratwicke said they considered re-exposing these frogs to chytrid to test them for an immune response.

“We didn’t have enough frogs remaining on that experiment to really be able to test whether we had managed to get an immunized-type response,” Gratwicke said.

Gratwicke added, “What is more important to me than the mechanism of what’s causing the survival is can it be used as a tool to predict survival in the future?”

This is one of the questions Gratwicke and other researchers will be looking to answer in a new follow-up experiment. With this study, researchers will “screen more than 200 captive golden frogs … and see if they have these beneficial skin microbes.”

“That, for me, would be fantastic because it would give us a tool to screen golden frogs in captivity and get an idea of which ones might have a chance of surviving,” Gratwicke said. “Science is more often about incremental learning and we learned a lot from this experiment.”

Contact staff writer Kevin Green at 540-465-5137 ext. 155, or kgreen@nvdaily.com