SANIL GEORGE & JESSICA SHARTOUNY
Ewwww. Frog slime just could be the source of the next flu drug. It’s really not a crazy idea, though. Scientists have spent decades searching for new drugs to combat viruses by mining proteins that animals make to fight off germs. And lately, proteins found in amphibian mucus have shown promise against HIV and herpes. Now it’s influenza.
David Holthausen is a graduate student in immunology at Emory University in Atlanta, Ga. He and his colleagues sampled slime from the skin of a frog. Called Hydrophylax bahuvistara, this frog species was discovered in southern India. Its mucus contains a host of proteins. The researchers tested 32 of them against a flu virus. Four showed promise. All but one, however, proved toxic to mammals. So the scientists focused on the last. They’re calling it urumin for a type of sword used in the region of India where this frog was found.
Urumin didn’t harm mammals. It did, however, seem to give several flu viruses a hard time.
Influenza viruses mutate frequently, forming new types, known as strains. The family of each strain is known by a series of letters and numbers. Holthausen and his group chose common disease-causing strains. Four belonged to the H3N2 family and eight to the H1N1 family. Urumin slowed somewhat the ability of H3N2 viruses to reproduce. It was particularly good, however, at killing H1N1 viruses. And that’s fortunate, because these are a more common family of strains that sicken people.
Mice treated with the frog-slime protein, also had a better chance of survival when exposed to a killer strain of flu. The slime protein even cut the reproduction of viruses in seven strains that had all become resistant to the effects of anti-viral drugs.
The new research shows that urumin works by blowing up flu virus particles. It targets a so-called stalk region of a protein in the H1 strains.
It will take more work to turn urumin into a true drug. But in time, it could serve as the basis for a new family of flu vaccines. Holthausen’s group described its new findings April 18 in Immunity.
colleague Someone who works with another; a co-worker or team member.
germ Any one-celled microorganism, such as a bacterium, fungal species or virus particle. Some germs cause disease. Others can promote the health of more complex organisms, including birds and mammals. The health effects of most germs, however, remain unknown.
graduate student Someone working toward an advanced degree by taking classes and performing research. This work is done after the student has already graduated from college (usually with a four-year degree).
H1N1 A type of influenza virus that infects mainly swine. A few of the strains have developed the ability to spread in people as well.
HIV (short for Human Immunodeficiency Virus) A potentially deadly virus that attacks cells in the body’s immune system and causes acquired immune deficiency syndrome, or AIDS.
immunity The ability of an organism to resist a particular infection or poison by providing cells to remove, kill or disarm the dangerous substance or infectious germ.
immunology The field of biomedicine that deals with the immune system. A doctor or scientist who works in that field is known as an immunologist.
influenza (also known as flu) A highly contagious viral infection of the respiratory passages causing fever and severe aching. It often occurs as an epidemic.
mammal A warm-blooded animal distinguished by the possession of hair or fur, the secretion of milk by females for feeding their young, and (typically) the bearing of live young.
mucus A slimy substance produced in the lungs, nose, digestive system and other parts of the body to protect against infection. Mucus is made mainly of water but also includes salt and proteins such as mucins. Some animals use mucus for other purposes, such as to move across the ground or to defend themselves against predators.
mutation (v. mutate) Some change that occurs to a gene in an organism’s DNA. Some mutations occur naturally. Others can be triggered by outside factors, such as pollution, radiation, medicines or something in the diet. A gene with this change is referred to as a mutant.
particle A minute amount of something.
protein Compounds made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Among the better-known, stand-alone proteins are the hemoglobin (in blood) and the antibodies (also in blood) that attempt to fight infections. Medicines frequently work by latching onto proteins.
resistance (as in drug resistance) The reduction in the effectiveness of a drug to cure a disease, usually a microbial infection. (as in disease resistance) The ability of an organism to fight off disease. (n. resistant)
species A group of similar organisms capable of producing offspring that can survive and reproduce.
strain (in biology) Organisms that belong to the same species that share some small but definable characteristics. For example, biologists breed certain strains of mice that may have a particular susceptibility to disease. Certain bacteria or viruses may develop one or more mutations that turn them into a strain that is immune to the ordinarily lethal effect of one or more drugs.
toxic Poisonous or able to harm or kill cells, tissues or whole organisms. The measure of risk posed by such a poison is its toxicity.
vaccine A biological mixture that resembles a disease-causing agent. It is given to help the body create immunity to a particular disease. The injections used to administer most vaccines are known as vaccinations.
virus Tiny infectious particles consisting of RNA or DNA surrounded by protein. Viruses can reproduce only by injecting their genetic material into the cells of living creatures. Although scientists frequently refer to viruses as live or dead, in fact no virus is truly alive. It doesn’t eat like animals do, or make its own food the way plants do. It must hijack the cellular machinery of a living cell in order to survive.
Journal: D.J. Holthausen et al. An amphibian host defense peptide Is virucidal for human H1 hemagglutinin-bearing influenza viruses. Immunity. Vol. 46, April 18, 2017, p. 587. doi: 10.1016/j.immuni.2017.03.018.