Researchers have identified the key factor allowing certain amphibian populations to recover from a global fungal disease that has devastated frogs and toads worldwide. The timing of immune system development during the tadpole stage determines survival rates after metamorphosis. The findings were published in Nature Chemical Biology.
A team from University College London, ZSL and Imperial College London examined common midwife toads around four lakes in the Pyrenees. Populations at three lakes rebounded despite ongoing exposure to the chytrid fungus Batrachochytrium dendrobatidis, while one lake's population continued to decline.
The study found that recovering populations produce antimicrobial peptides earlier, while still tadpoles. This gives adults established defenses before their skin becomes vulnerable to the fungus, which feeds on keratin.
Lead author Dr Phillip Jervis said the disease kills amphibians during the transition from tadpole to adult. He noted that mature immunity at the tadpole stage helps populations persist.
Analysis using mass spectrometry identified 1,152 peptides from toad skin, of which only seven were previously known. Populations with greater peptide diversity in the tadpole phase showed higher survival rates.
Senior author Professor Alethea Tabor said the peptides could provide new leads for treating human infections amid rising antimicrobial resistance.