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Frog fungus fights back

Posted by on Saturday, July 20, 2019 in Uncategorized.

Amphibian populations have been declining around the world for more than 40 years. One culprit is the fungus B. dendrobatidis, which causes the disease chytridiomycosis. Although amphibians have robust immune defenses, the response to this pathogen is often ineffective, suggesting that the fungus somehow counters the immune response.

Evolution@Vanderbilt member Louise Rollins-Smith, Professor of Pathology, Microbiology, and Immunology, and colleagues previously discovered that the fungus produces two small molecules (methylthioadenosine and kynurenine) that inhibit frog immune cells. They have now discovered that spermidine is another fungus-produced molecule that inhibits frog immune cell proliferation and viability. They demonstrated that spermidine is required for fungal growth, determined its effective concentration, and identified its biosynthetic pathway. They also found that a non-inhibitory concentration of methylthioadenosine enhances spermidine’s inhibitory action. The work was published in the journal Infection and Immunity.

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