Genome-wide transcriptional response of Silurana (Xenopus) tropicalis to infection with the deadly chytrid fungus.
Emerging infectious diseases are of great concern for both wildlife and humans. Several highly virulent fungal pathogens have recently been discovered in natural populations, highlighting the need for a better understanding of fungal-vertebrate host-pathogen interactions. Because most fungal pathogens are not fatal in the absence of other predisposing conditions, host-pathogen dynamics for deadly fungal pathogens are of particular interest. The chytrid fungus Batrachochytrium dendrobatidis (hereafter Bd) infects hundreds of species of frogs in the wild. It is found worldwide and is a significant contributor to the current global amphibian decline. However, the mechanism by which Bd causes death in amphibians, and the response of the host to Bd infection, remain largely unknown. Here we use whole-genome microarrays to monitor the transcriptional responses to Bd infection in the model frog species, Silurana (Xenopus) tropicalis, which is susceptible to chytridiomycosis. To elucidate the immune response to Bd and evaluate the physiological effects of chytridiomycosis, we measured gene expression changes in several tissues (liver, skin, spleen) following exposure to Bd. We detected a strong transcriptional response for genes involved in physiological processes that can help explain some clinical symptoms of chytridiomycosis at the organismal level. However, we detected surprisingly little evidence of an immune response to Bd exposure, suggesting that this susceptible species may not be mounting efficient innate and adaptive immune responses against Bd. The weak immune response may be partially explained by the thermal conditions of the experiment, which were optimal for Bd growth. However, many immune genes exhibited decreased expression in Bd-exposed frogs compared to control frogs, suggesting a more complex effect of Bd on the immune system than simple temperature-mediated immune suppression. This study generates important baseline data for ongoing efforts to understand differences in response to Bd between susceptible and resistant frog species and the effects of chytridiomycosis in natural populations.
Rosenblum
Erica Bree
EB
Department of Biological Sciences, University of Idaho, Moscow, Idaho, United States of America. rosenblum@uidaho.edu
Poorten
Thomas J
TJ
Settles
Matthew
M
Murdoch
Gordon K
GK
Robert
Jacques
J
Maddox
Nicole
N
Eisen
Michael B
MB
D000818:Animals; D015870:Gene Expression; D020022:Genetic Predisposition to Disease; D016678:Genome; D054884:Host-Pathogen Interactions; D008099:Liver / Q000378:metabolism; D009181:Mycoses / Q000235:genetics* / Q000382:microbiology; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012867:Skin / Q000378:metabolism; D013154:Spleen / Q000378:metabolism; D014158:Transcription, Genetic; D014981:Xenopus
Curr Opin Microbiol. 2003 Aug;6(4):327-31
12941399
Mol Immunol. 2008 Mar;45(5):1485-93
17915330
J Comp Physiol B. 1997 May;167(4):256-63
9203367
Transplantation. 2007 Jan 27;83(2):159-66
17264812
Am J Clin Dermatol. 2003;4(5):347-64
12688839
Nat Rev Microbiol. 2005 Apr;3(4):281-94
15806094
Proc Natl Acad Sci U S A. 2006 Feb 28;103(9):3165-70
16481617
Genetics. 2007 Jun;176(2):1119-30
17435227
Chem Res Toxicol. 2008 Jan;21(1):70-83
18052394
Oecologia. 2006 Jan;146(4):531-40
16205955
Philos Trans R Soc Lond B Biol Sci. 2009 Jan 12;364(1513):85-98
18930879
Biostatistics. 2003 Apr;4(2):249-64
12925520
Aust Vet J. 2004 Jul;82(7):434-9
15354853
Dev Dyn. 2009 Jun;238(6):1249-70
19253402
Dis Aquat Organ. 2007 Aug 13;77(1):1-9
17933392
Science. 2009 Jan 9;323(5911):227
18974316
Mycologia. 2004 Jan-Feb;96(1):9-15
21148822
Mol Immunol. 2009 Jul;46(11-12):2317-32
19409617
Dis Aquat Organ. 2005 Dec 30;68(1):47-50
16465833
Dis Aquat Organ. 2004 Aug 9;60(2):141-8
15460858
Br J Haematol. 1975 Mar;29(3):385-95
1201157
Dev Comp Immunol. 2007;31(4):383-93
16926047
Vet Immunol Immunopathol. 2008 Sep 15;125(1-2):47-70
18565595
Drug Metab Dispos. 2004 Apr;32(4):437-41
15039297
Infect Immun. 2005 Oct;73(10):6689-703
16177346
Annu Rev Immunol. 1989;7:251-75
2653371
Ecology. 2006 Jul;87(7):1671-83
16922318
Proc Natl Acad Sci U S A. 1998 Jul 21;95(15):9031-6
9671799
Comp Med. 2002 Jun;52(3):265-8
12102573
Nature. 1976 Dec 16;264(5587):642-4
1004605
Infect Immun. 2001 Aug;69(8):5115-20
11447193
Hepatology. 1989 May;9(5):710-4
2651269
Proc Natl Acad Sci U S A. 2008 Nov 4;105(44):17034-9
18852473
Bioinformatics. 2003 Jan 22;19(2):185-93
12538238
Nat Rev Immunol. 2004 Jan;4(1):1-23
14661066
Int J Biochem Cell Biol. 2005 Mar;37(3):535-40
15618010
Dis Aquat Organ. 2007 Sep 14;77(2):113-8
17972752