MHC genotypes associate with resistance to a frog-killing fungus

Edited by Max D. Cooper, Emory University, Atlanta, GA, and approved August 22, 2011 (received for review April 29, 2011)
September 26, 2011
108 (40) 16705-16710

Abstract

The emerging amphibian disease chytridiomycosis is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). Amphibian populations and species differ in susceptibility to Bd, yet we know surprisingly little about the genetic basis of this natural variation. MHC loci encode peptides that initiate acquired immunity in vertebrates, making them likely candidates for determining disease susceptibility. However, MHC genes have never been characterized in the context of chytridiomycosis. Here, we performed experimental Bd infections in laboratory-reared frogs collected from five populations that show natural variation in Bd susceptibility. We found that alleles of an expressed MHC class IIB locus associate with survival following Bd infection. Across populations, MHC heterozygosity was a significant predictor of survival. Within populations, MHC heterozygotes and individuals bearing MHC allele Q had a significantly reduced risk of death, and we detected a significant signal of positive selection along the evolutionary lineage leading to allele Q. Our findings demonstrate that immunogenetic variation affects chytridiomycosis survival under controlled experimental conditions, confirming that host genetic polymorphisms contribute to chytridiomycosis resistance.

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Data Availability

Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos. JN638850–JN638882).

Acknowledgments

We thank S. Bogdanowicz, M. Lenker, K. Kiemnec, J. Q. Richmond, M. Schlaepfer, E. Davidson, V. Miera, R. Retallick, and E. Retallick for laboratory and field support, and A. Longo, G. Becker, and J. Cavatorta for constructive comments on the manuscript. This work was funded by Cornell University, Population and Evolutionary Process National Science Foundation (NSF) Grant DEB-0815315 (to K.R.Z.), and NSF Doctoral Dissertation Improvement Grant DEB-0909013 (to A.E.S.).

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Published in

Go to Proceedings of the National Academy of Sciences
Proceedings of the National Academy of Sciences
Vol. 108 | No. 40
October 4, 2011
PubMed: 21949385

Classifications

Data Availability

Data deposition: The sequences reported in this paper have been deposited in the GenBank database (accession nos. JN638850–JN638882).

Submission history

Published online: September 26, 2011
Published in issue: October 4, 2011

Keywords

  1. emerging infectious disease
  2. experimental infection
  3. major histocompatibility complex
  4. molecular evolution
  5. Ranidae

Acknowledgments

We thank S. Bogdanowicz, M. Lenker, K. Kiemnec, J. Q. Richmond, M. Schlaepfer, E. Davidson, V. Miera, R. Retallick, and E. Retallick for laboratory and field support, and A. Longo, G. Becker, and J. Cavatorta for constructive comments on the manuscript. This work was funded by Cornell University, Population and Evolutionary Process National Science Foundation (NSF) Grant DEB-0815315 (to K.R.Z.), and NSF Doctoral Dissertation Improvement Grant DEB-0909013 (to A.E.S.).

Notes

This article is a PNAS Direct Submission.

Authors

Affiliations

Anna E. Savage1 [email protected]
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853
Kelly R. Zamudio
Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853

Notes

1
To whom correspondence should be addressed. E-mail: [email protected].
Author contributions: A.E.S. designed research; A.E.S. performed research; A.E.S. analyzed data; and A.E.S. and K.R.Z. wrote the paper.

Competing Interests

The authors declare no conflict of interest.

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    MHC genotypes associate with resistance to a frog-killing fungus
    Proceedings of the National Academy of Sciences
    • Vol. 108
    • No. 40
    • pp. 16483-16857

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