Frog Slime May Protect Against Deadly Flu Strains


Turned into a mist and squirted into the noses of mice, an ingredient from the slime of a frog’s skin protected the rodents against flu strains deadly to humans.

The research was published this week in the journal Immunity. Scientists from Emory University led by senior author Joshy Jacob, associate professor of Microbiology and Immunology at Emory Vaccine Center and Emory School of Medicine, tested 32 peptides found on a south Indian frog for their flu-fighting effectiveness.

The Hydrophylax malabaricus (seen here) is a close species of the Hydrophylax bahuvistara which overlaps partly in range. Credit: Boldsystems.orgCC BY-NC-SA 3.0

“I was almost knocked out of my chair,” Jacob said in an Emory news release. “In the beginning, I thought that when you do the drug discovery, you have to go through thousands of drug candidates, even a million, before you get one or two hits. And here we did 32 peptides and we had four hits.”

Frogs secrete the peptide-packed slime to defend it against bacteria. This unusual immune system has garnered the interest of scientists.

Frogs cannot contract the human flu, so the peptides Jacob discovered must exist to protect the frog against something else.

Jacob and his colleagues named one particularly potent peptide “urumin” after a sword called “urumi” used in southern India hundreds of years ago.

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Peptides are amino acid chains that make up proteins. “Some antibacterial peptides work by punching holes in cell membranes, and are thus toxic to mammalian cells,” according to the Emory news release. “Some antiviral peptides from the frogs are toxic in this way, but urumin was not. Instead, it appears only to disrupt the integrity of flu virus, as seen through electron microscopy.”

What else made urumin different from the other peptides? “This peptide specifically targeted the conserved stalk region of H1 hemagglutinin and was effective against drug-resistant H1 influenza viruses,” according to the research paper abstract.

The discovery of this peptide is a potentially important one to global public health.  According to Jacob, hemagglutinin is also considered an important target in proposed universal flu vaccines. “This specificity could be valuable, because current anti-influenza drugs target other parts of the virus,” the Emory news release explains.

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According to World Health Organization (WHO), influenza is unpredictable and potentially catastrophic. In 1918, as many as 50 million people died during a global influenza pandemic called Spanish flu. The flu is very contagious, with one sneeze sending out thousands of highly infectious droplets that land on surfaces.

“The threat of the next pandemic looms large,” according to WHO.

The H1N1 virus spread worldwide in 2009 and killed 200,000 people, many of them young people not previously thought to be at risk. This sounded an alarm about the extent of the flu’s might.

“They constantly evolve and mutate,” according to WHO. “It is still unknown where the next pandemic will strike.”