A frog found in India secretes a substance that has been shown to be highly effective at killing influenza viruses.
Researchers at Emory University in Atlanta say the secreted peptide — a subunit of a protein chain — kills dozens of flu strains that plague humans. It is effective against H1 viruses, including ones that could cause pandemics.
Unlike humans, frogs don't have an immune system that is capable of protecting them against pathogens like viruses and bacteria. But they do produce a slimy mucus that does the job for them.
Researchers at Emory screened 32 peptides derived from the mucus of the frog, called Bahuvistara, and found one that was effective against all H1 viruses. The frog is found in the southern Indian province of Kerala.
Joshy Jacob, a professor of microbiology and immunology at Emory's vaccine center and senior author of the study, describing the peptide in the journal Immunity. He and his colleagues administered the peptide to mice and then exposed them to H1 viruses. He said it protected the animals from infection.
"The beauty of this peptide is that it directly kills the virus. It's virucidal. So if you put the peptide and the virus together, it actually destroys the virus," Jacob said.
The researchers named the peptide urumin, after a sword blade that snaps and bends like a whip.
Jacob said the mucus is collected from the frog after exposing it to a mild electric current, which makes the amphibians secrete the antiviral agent.
Three dozen peptides
After identifying the more than three dozen immune peptides in the mucus, the protein building blocks were made synthetically in the lab.
Four emerged as antiviral candidates. But one, urumin, killed all H1 viruses.
Jacob said an flu-fighting peptide could be especially useful when vaccines are not available or when circulating viral strains become resistant to current drugs.
He said one of the next challenges would be turning the effective peptide into a pill or injection to protect humans from viruses.
"It's like when you get a headache, you take a Motrin [a painkiller]. [The peptide] doesn't keep you from getting [the flu] again, but it kills the virus. It's like taking an antibiotic for bacterial infection. You take this for a flu infection," Jacob said.
Jacob said the peptide was not effective against seasonal flu viruses that mutate rapidly. But researchers plan on testing more of the frog-derived peptides to try to find others that work against other types of influenza virus.