Researchers from the Rajiv Gandhi Center for Biotechnology in Kerala, India, had been isolating peptides from the slime of local frogs. Researchers suspected it had evolved some form of anti-viral compound, so they took some of the frog's slime and found a peptide they're calling urumin.
In the study, now published in the journal Immunity, scientists investigated molecules known as "host defence peptides" produced in the mucus on the skin of the South Indian frog, showing that they could kill influenza A.
In the tests, urumin delivered through the nose protected unvaccinated mice from lethal doses of flu viruses.
Hydrophylax bahuvistaraa frog superimposed on a green background with the shapes of flu viruses in lighter green. A team, led by Joshy Jacob from Emory University, made a decision to screen 32 of these peptides against an influenza A strain. In the beginning, I thought that when you do drug discovery, you have to go through thousands of drug candidates, even a million, before you get one or two hits.
It specifically targeted the H1 strain family which includes the swine flu sub-type that led to a major pandemic in 2009 and is now just another form of seasonal flu. In today's study, first scientists screened 32 frog peptides against various flu strains, and found that four of them could fight off the virus.
Instead, urumin appears to only disrupt the integrity of flu virus, as seen through electron microscopy.
Developing antimicrobial peptides into effective drugs has been a challenge in the past, partly because enzymes in the body can break them down. This specificity could be valuable because current anti-influenza drugs target other parts of the virus, Jacob says.
More research is needed to understand the way urumin works, but so far, the researchers have established that it targets a viral surface protein called hemagluttinin. "What this peptide does is it binds to the hemagglutinin and destabilizes the virus". In the lab, researchers isolated molecules from the secretion and tested them on human blood cells infected with various flu virus strains. "And then it kills the virus".