Deadly trick of amphibian-killing fungus focus of intense research

NASHVILLE, Oct. 18 (UPI) -- A killer fungus decimating amphibians globally works its deadly effect with a chemical causing its hosts' white blood cells to self-destruct, scientists say.

Since the 1980s, many species of frogs and salamanders have been driven to extinction by the chytrid fungus, Batrachochytrium dendrobatidis, which attacks the amphibians' skin cells and, in severe infections, causes death by heart failure.

Researchers say this is puzzling as amphibians are thought to have robust immune systems to deal with microorganisms common in their watery habitats.

"Amphibians have really capable immune systems, yet here they are stumbling against this skin pathogen," Vanderbilt University immunologist Louise Rollins-Smith told NewScientist.com. "Why does this pathogen seem to fail to activate that robust response?"

The reason, they said, is because chytrids secrete a chemical molecule that inhibits the production of lymphocytes that normally power the immune system and makes them more likely to self-destruct in a process called apoptosis -- the way old or damaged cells are naturally cleared from the body.

The loss of lymphocytes leaves the animals without the ability to eradicate the chytrid infection before it does further damage to their skin cells, the researchers said.

While the researchers have not yet been able to identify the molecule responsible, if it can be discovered it may be possible to combat the disease by bolstering species' immune systems, they said.