Navigation Links
Frog-killing fungus paralyzes amphibian immune response
Date:10/19/2013

A fungus that is killing frogs and other amphibians around the world releases a toxic factor that disables the amphibian immune response, Vanderbilt University investigators report Oct. 18 in the journal Science.

The findings represent "a step forward in understanding a long-standing puzzle why the amphibian immune system seems to be so inept at clearing the fungus," said Louise Rollins-Smith, Ph.D., associate professor of Pathology, Microbiology and Immunology. Although the identity of the toxic fungal factor (or factors) remains a mystery, its ability to inhibit a wide range of cell types including cancerous cells suggests that it may offer new directions for the development of immunosuppressive or anti-cancer agents.

The populations of amphibian species have been declining worldwide for more than 40 years. In the late 1990s, researchers discovered that an ancient fungus, Batrachochytrium dendrobatidis, was causing skin infections, and the fungus is now recognized as a leading contributor to global amphibian decline.

Rollins-Smith, an immunologist, and her colleagues have been studying the immune response to the fungus for more than 10 years.

"Amphibians have excellent and complex immune systems nearly as complex as humans and they should be able to recognize and clear the fungus," she said.

In early studies, the investigators demonstrated that some frogs produce anti-microbial peptides in the skin that offer a first layer of defense against the fungus. But when the fungus gets into the layers of the skin, Rollins-Smith said, the conventional lymphocyte (immune cell)-mediated immune response should be activated to clear it.

They found in the current studies that recognition of the fungus by macrophage and neutrophil cells was not impaired.

"We think it's not a block at the initial recognition stage," Rollins-Smith said. "The macrophages and neutrophils can see it as a pathogen, they can eat it up, they can do their thing."

But during the next stage of the immune response, when lymphocytes should be activated, the fungus exerts its toxic effects. The investigators demonstrated that B. dendrobatidis cells and supernatants (the incubation liquid separated from the cells) impaired lymphocyte proliferation and induced cell death of lymphocytes from frogs, mice and humans. The toxic fungal factor also inhibited the growth of cancerous mammalian cell lines.

The toxic factor was resistant to heat and proteases (enzymes that cut proteins into pieces), suggesting that it is not a protein. It appears to be a component of the cell wall, because drugs that interfere with cell wall synthesis reduce its inhibitory activity and because the zoospore an immature form of the fungus that lacks a cell wall does not produce the factor.

The new findings suggest the possibility that toxic factors in addition to acting locally to inhibit the immune response might also get into the circulation and have neurotoxic effects, Rollins-Smith said.

"Fungal infection causes rapid behavioral changes frogs become lethargic and start to crawl out of the water suggesting that even though the fungus stays in the skin, the toxic material is having effects elsewhere."

The studies, led by graduate students J. Scott Fites and Jeremy Ramsey, could also suggest new conservation measures for species that may be medically important.

"Amphibian skin has long been favored in folklore for its medicinal properties," Rollins-Smith said. "Frogs are a rich source of potentially useful molecules that might work against human pathogens."


'/>"/>

Contact: Leigh MacMillan
leigh.macmillan@vanderbilt.edu
615-322-4747
Vanderbilt University Medical Center
Source:Eurekalert  

Related biology news :

1. Buttercups alert farmers to first signs of subarctic fungus in the UK
2. Beetle-fungus disease threatens crops and landscape trees in Southern California
3. NYBG scientists identify 81 new plant and fungus species
4. How an ancestral fungus may have influenced coal formation
5. How a common fungus knows when to attack
6. Researchers launch new Rust-Tracker to monitor deadly wheat fungus in 27 nations
7. Natural fungus may provide effective bed bug control
8. University of Tennessee researchers find fungus has cancer-fighting power
9. Fungus responsible for 5 deaths in the wake of massive tornado
10. The secret sex life of the penicillin-producing fungus could make it more productive
11. More accurate, sensitive DNA test allows early identification of fungus causing WNS
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Frog-killing fungus paralyzes amphibian immune response
(Date:5/23/2017)... May 23, 2017  Hunova, the first robotic gym for the rehabilitation ... officially launched in Genoa, Italy . The first 30 ... and the USA . The technology was developed and ... by the IIT spin-off Movendo Technology thanks to a 10 million euro ... Release, please click: ...
(Date:5/6/2017)... RAM Group , Singaporean based ... in biometric authentication based on a novel  ... to perform biometric authentication. These new sensors are based on ... Ram Group and its partners. This sensor will have ... and security. Ram Group is a next generation ...
(Date:4/18/2017)... , April 18, 2017  Socionext Inc., a global expert in ... media edge server, the M820, which features the company,s hybrid codec ... provided by Tera Probe, Inc., will be showcased during the upcoming ... NAB show at the Las Vegas Convention ... Click ...
Breaking Biology News(10 mins):
(Date:10/11/2017)... and LAGUNA HILLS, Calif. , Oct. ... Cancer Research, London (ICR) and University ... SKY92, SkylineDx,s prognostic tool to risk-stratify patients with multiple myeloma ... MUK nine . The University of Leeds ... partly funded by Myeloma UK, and ICR will perform the ...
(Date:10/10/2017)... ... October 10, 2017 , ... San Diego-based team building and ... rebranding initiative announced today. The bold new look is part of a transformation ... moves into a significant growth period. , It will also expand its service offering ...
(Date:10/10/2017)... DALLAS , Oct. 10, 2017 International research firm ... IoT Strategy, will speak at the TMA 2017 Annual Meeting , ... key trends in the residential home security market and how smart safety ... ... "The ...
(Date:10/9/2017)...  BioTech Holdings announced today identification and patenting ... stem cell therapy prevents limb loss in animal ... that treatment with ProCell resulted in more than ... to standard bone marrow stem cell administration.  Interestingly, ... of therapeutic effect.  ...
Breaking Biology Technology: