Have you ever thought, that frog mucus can kill flu virus..? A research shows that a component of the skin mucus secreted by the South Indian frogs has the ability to kill H1 variety of influenza viruses, researchers from the Emory Vaccine Center and also the Rajiv Gandhi Center for Biotechnology in India have discovered.
Frogs skins were known to secrete peptides which defend them against bacteria. The research, published on Tuesday in Immunity, suggests that peptides represent a resource for the antiviral drug discovery as well.
Anti-flu peptides could become handy when the vaccines for flu are unavailable, in the case of a new pandemic strain or when the circulating strains become resistant to current drugs, said the senior author Joshy Jacob, PhD, an associate professor of microbiology and immunology at the Emory Vaccine Center and Emory University School of Medicine.
The first author of the paper is a graduate student David Holthausen, and the research grew up with the collaboration of M.R. Pillai, PhD and also Sanil George, PhD from the Rajiv Gandhi Center for Biotechnology.
Jacob and also his colleagues named one of the antiviral peptides they identified as urumin, after a whip-like sword called "urumi" which was used in southern India centuries ago. Urumin was found in the skin secretions of the Indian frog Hydrophylax bahuvistara, which were collected after the mild electrical stimulation.
Peptides are the short chains of amino acids, which are the building blocks of proteins. Some anti-bacterial peptides work by punching holes in the cell membranes, and are thus toxic to the mammalian cells. Some of the antiviral peptides from frogs were toxic in this way, but urumin was not. Instead, urumin appears to only disrupt the integrity of flu virus, as seen through the electron microscopy.
"I was almost knocked off my chair. 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 1 or 2 hits. And here we did 32 peptides, and we had 4 hits," Jacob said.
It turns out that urumin binds stalk of the hemagglutinin, a less variable region of the flu virus which is also the target of proposed universal vaccines. This specificity could be more worthy because current anti-influenza drugs target other parts of the virus, Jacob said. Because the flu viruses from humans cannot infect frogs, producing urumin probably confers an advantage on the frogs in fighting some other pathogens, said Jacob.
When delivered intranasally, urumin protected the unvaccinated mice against a lethal dose of some flu viruses. Urumin was specific for the H1 strains of flu, such as the 2009 pandemic strain, and was not effective against some other current strains such as H3N2.
Developing antimicrobial peptides into the effective drugs has been a challenge in the past, partly because of the enzymes in body can break them down. Jacob's lab is now exploring the ways to stabilize antiviral peptides such as urumin, as well as looking for the frog-derived peptides which are active against other viruses like dengue and Zika. Jacob's lab is based at the Yerkes National Primate Research Center.
The research was supported by Emory University and also by the Office of Research Infrastructure Programs (Primate centers: P51OD11132).