Frog slime protein fights off the flu

The next flu drug could come from frog mucus. It’s not as crazy as it sounds: For decades, scientists have searched for new antiviral drugs by mining proteins that animals produce to protect themselves from microbes. In lab tests, proteins found in amphibian secretions can defend against HIV, herpes and now the flu.

David Holthausen of Emory University and his colleagues sampled slime from the skin of Hydrophylax bahuvistara, a recently discovered frog species from southern India. They tested the influenza-fighting ability of 32 slime proteins, and four showed promise. Of those, three proved toxic to mammals. 

But one peptide, dubbed urumin, was safe for mammals and showed a propensity for fighting off the flu. When exposed to four H3N2 and eight H1N1 strains, urumin inhibited H3N2 viruses to a degree but was particularly adept at killing H1N1 viruses, which are more common among humans. The frog slime protein even cut viral numbers in a set of seven drug-resistant strains, and protected mice from flu infection. The team found that urumin blows up flu virus particles by targeting the stalk region of the hemagglutinin protein in H1 varieties. With further development, urumin could form the basis of future influenza drugs, the researchers write April 18 in Immunity. 

Editor’s note: This article was updated on April 19, 2017, to clarify the methodology and results of the study.