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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.
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Lymphocyte Inhibition by the Salamander-Killing Chytrid Fungus, Batrachochytrium salamandrivorans
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.
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- PAR ID:
- 10344654
- Editor(s):
- Noverr, Mairi C.
- Date Published:
- Journal Name:
- Infection and Immunity
- Volume:
- 90
- Issue:
- 3
- ISSN:
- 0019-9567
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1128/iai.00020-22
