An official website of the United States government
Abstract Batrachochytrium salamandrivorans ( Bsal ) is a fungal pathogen of amphibians that is emerging in Europe and could be introduced to North America through international trade or other pathways. To evaluate the risk of Bsal invasion to amphibian biodiversity, we performed dose-response experiments on 35 North American species from 10 families, including larvae from five species. We discovered that Bsal caused infection in 74% and mortality in 35% of species tested. Both salamanders and frogs became infected and developed Bsal chytridiomycosis. Based on our host susceptibility results, environmental suitability conditions for Bsal , and geographic ranges of salamanders in the United States, predicted biodiversity loss is expected to be greatest in the Appalachian Region and along the West Coast. Indices of infection and disease susceptibility suggest that North American amphibian species span a spectrum of vulnerability to Bsal chytridiomycosis and most amphibian communities will include an assemblage of resistant, carrier, and amplification species. Predicted salamander losses could exceed 80 species in the United States and 140 species in North America.
more »
« less
Batrachochytrium salamandrivorans Can Devour More than Salamanders
Batrachochytrium salamandrivorans is an emerging fungus that is causing salamander declines in Europe. We evaluated whether an invasive frog species (Cuban treefrog, Osteopilus septentrionalis) that is found in international trade could be an asymptomatic carrier when exposed to zoospore doses known to infect salamanders. We discovered that Cuban treefrogs could be infected with B. salamandrivorans and, surprisingly, that chytridiomycosis developed in animals at the two highest zoospore doses. To fulfill Koch’s postulates, we isolated B. salamandrivorans from infected frogs, exposed eastern newts (Notophthalmus viridescens) to the isolate, and verified infection and disease by histopathology. This experiment represents the first documentation of B. salamandrivorans chytridiomycosis in a frog species and substantially expands the conservation threat and possible mobilization of this pathogen in trade.
more »
« less
- Award ID(s):
- 1814520
- PAR ID:
- 10295478
- Date Published:
- Journal Name:
- Journal of wildlife diseases
- Volume:
- 57
- Issue:
- 4
- ISSN:
- 0090-3558
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Introduction One of the most important emerging infectious diseases of amphibians is caused by the fungal pathogen Batrachochytrium salamandrivorans (Bsal) . Bsal was recently discovered and is of global concern due to its potential to cause high mortality in amphibians, especially salamander species. To date, little has been reported on the pathophysiological effects of Bsal ; however, studies of a similar fungus, B. dendrobatidis (Bd) , have shown that electrolyte losses and immunosuppression likely play a key role in morbidity and mortality associated with this disease. The goal of this study was to investigate pathophysiological effects and immune responses associated with Bsal chytridiomycosis using 49 rough-skinned newts ( Taricha granulosa ) as the model species. Methods Taricha granulosa were exposed to a 1 × 10 7 per 10 mL dose of Bsal zoospores and allowed to reach various stages of disease progression before being humanely euthanized. At the time of euthanasia, blood was collected for biochemical and hematological analyses as well as protein electrophoresis. Ten standardized body sections were histologically examined, and Bsal -induced skin lesions were counted and graded on a scale of 1–5 based on severity. Results Results indicated that electrolyte imbalances and dehydration induced by damage to the epidermis likely play a major role in the pathogenesis of Bsal chytridiomycosis in this species. Additionally, Bsal -infected, clinically diseased T. granulosa exhibited a systemic inflammatory response identified through alterations in complete blood counts and protein electrophoretograms. Discussion Overall, these results provide foundational information on the pathogenesis of this disease and highlight the differences and similarities between Bsal and Bd chytridiomycosis.more » « less
-
null (Ed.)Abstract Two species of parasitic fungi from the phylum Chytridiomycota (chytrids)are annihilating global amphibian populations. These chytrid species— Batrachochytrium dendrobatidis and B. salamandrivorans —have high rates of mortality and transmission. Uponestablishing infection in amphibians, chytrids rapidly multiply within the skin anddisrupt their hosts’ vital homeostasis mechanisms. Current disease models suggest thatchytrid fungi locate and infect their hosts during a motile, unicellular ‘zoospore’ lifestage. Moreover, other chytrid species parasitize organisms from across the tree oflife, making future epidemics in new hosts a likely possibility. Efforts to mitigate thedamage and spread of chytrid disease have been stymied by the lack of knowledge aboutbasic chytrid biology and tools with which to test molecular hypotheses about diseasemechanisms. To overcome this bottleneck, we have developed high-efficiency delivery ofmolecular payloads into chytrid zoospores using electroporation. Our electroporationprotocols result in payload delivery to between 75 and 97% of living cells of threespecies: B. dendrobatidis, B. salamandrivorans, and anon-pathogenic relative, Spizellomyces punctatus .This method lays the foundation for molecular genetic tools needed to establishecological mitigation strategies and answer broader questions in evolutionary and cellbiology.more » « less
-
Noverr, Mairi C. (Ed.)ABSTRACT Amphibian populations have been declining around the world for more than five decades, and the losses continue. Although causes are complex, major contributors to these declines are two chytrid fungi, Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans , which both cause the disease termed chytridiomycosis. Previously, we showed that B. dendrobatidis impedes amphibian defenses by directly inhibiting lymphocytes in vitro and in vivo by release of soluble metabolites, including kynurenine (KYN), methylthioadenosine (MTA), and spermidine (SPD). Here, we show that B. salamandrivorans cells and cell-free supernatants also inhibit amphibian lymphocytes as well as a human T cell line. As we have shown for B. dendrobatidis , high-performance liquid chromatography (HPLC) and mass spectrometry revealed that KYN, MTA, and SPD are key metabolites found in the B. salamandrivorans supernatants. Production of inhibitory factors by B. salamandrivorans is limited to mature zoosporangia and can occur over a range of temperatures between 16°C and 26°C. Taken together, these results suggest that both pathogenic Batrachochytrium fungi have evolved similar mechanisms to inhibit lymphocytes in order to evade clearance by the amphibian immune system.more » « less
-
Amphibian populations have been declining around the world for more than five decades, and the losses continue. Although causes are complex, major contributors to these declines are two chytrid fungi, Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans, which both cause the disease termed chytridiomycosis. Previously we showed that B. dendrobatidis impedes amphibian defenses by directly inhibiting lymphocytes in vitro and in vivo by release of soluble metabolites including kynurenine (KYN), methylthioadenosine (MTA), and spermidine (SPD). Here we show that B. salamandrivorans cells and cell-free supernatants also inhibit amphibian lymphocytes as well as a human T cell line. As we have shown for B. dendrobatidis, HPLC and mass spectrometry revealed that KYN, MTA, and SPD are key metabolites found in the B. salamandrivorans supernatants. Production of inhibitory factors by B. salamandrivorans is limited to mature zoosporangia and can occur over a range of temperatures between 16°C and 26C. Taken together, these results suggest that both pathogenic Batrachochytrium fungi have evolved similar mechanisms to inhibit lymphocytes in order to evade clearance by the amphibian immune system.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- The DOI is not currently available.
