Advertisement

Functional variation at an expressed MHC class IIβ locus associates with Ranavirus infection intensity in larval anuran populations

  • Anna E. SavageEmail author
  • Carly R. Muletz-Wolz
  • Evan H. Campbell Grant
  • Robert C. Fleischer
  • Kevin P. Mulder
Original Article

Abstract

Infectious diseases are causing catastrophic losses to global biodiversity. Iridoviruses in the genus Ranavirus are among the leading causes of amphibian disease-related mortality. Polymorphisms in major histocompatibility complex (MHC) genes are significantly associated with variation in amphibian pathogen susceptibility. MHC genes encode two classes of polymorphic cell-surface molecules that can recognize and bind to diverse pathogen peptides. While MHC class I genes are the classic mediators of viral-acquired immunity, larval amphibians do not express them. Consequently, MHC class II gene diversity may be an important predictor of Ranavirus susceptibility in larval amphibians, the life stage most susceptible to Ranavirus. We surveyed natural populations of larval wood frogs (Rana sylvatica), which are highly susceptible to Ranavirus, across 17 ponds and 2 years in Maryland, USA. We sequenced the peptide-binding region of an expressed MHC class IIβ locus and assessed allelic and genetic diversity. We converted alleles to functional supertypes and determined if supertypes or alleles influenced host responses to Ranavirus. Among 381 sampled individuals, 26% were infected with Ranavirus. We recovered 20 unique MHC class IIβ alleles that fell into two deeply diverged clades and seven supertypes. MHC genotypes were associated with Ranavirus infection intensity, but not prevalence. Specifically, MHC heterozygotes and supertype ST1/ST7 had significantly lower Ranavirus infection intensity compared to homozygotes and other supertypes. We conclude that MHC class IIβ functional genetic variation is an important component of Ranavirus susceptibility. Identifying immunogenetic signatures linked to variation in disease susceptibility can inform mitigation strategies for combatting global amphibian declines.

Keywords

Major histocompatibility complex Ranidae Amplicon primers Roche 454 Rana sylvatica Lithobates sylvaticus 

Notes

Acknowledgements

Thank you to Nancy McInerney for assistance with lab work, Brian Gratwicke for conceptual feedback, NEARMI field crews for field work, and members of the Savage lab for helpful comments and edits on this manuscript. We thank Jesse Brunner for providing Ranavirus qPCR standards and Jonathon Volante for help with the hurdle model. We thank the US Food and Drug Administration and Marc Allard for providing a GS FLX+ to CCG. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U. S. Government. This is contribution number 683 of the U.S. Geological Survey Amphibian Research and Monitoring Initiative (ARMI).

Author contributions

AES and KPM conceived the study design. EHCG and RCF provided samples. AES, EHCG, and RCF provided funds and laboratory space. KPM and CRMW performed all the lab works. AES, KPM, CRMW, and EHGC analyzed the data. AES wrote the manuscript with input from all other authors.

Funding

This study was funded by an Association of Zoos and Aquariums Conservation Grant Fund award (12-1111) to AES and the USGS Amphibian Research and Monitoring Initiative (ARMI). KPM was supported by a doctoral student grant (PD/BD/52604/2014) from the Portuguese “Fundaçao para a Ciencia e a Tecnologia.”

Compliance with ethical standards

Competing interests

The authors have no conflicts of interest or competing interests to disclose.

Supplementary material

251_2019_1104_MOESM1_ESM.docx (413 kb)
ESM 1 (DOCX 412 kb)
251_2019_1104_MOESM2_ESM.csv (27 kb)
ESM 2 (CSV 27 kb)
251_2019_1104_MOESM3_ESM.xlsx (53 kb)
ESM 3 (XLSX 53 kb)
251_2019_1104_MOESM4_ESM.Rmd
ESM 4 (RMD 12 kb)

References

  1. Acevedo-Whitehouse K, Cunningham AA (2006) Is MHC enough for understanding wildlife immunogenetics? Trends Ecol Evol 21(8):433–438Google Scholar
  2. Aguilar A, Roemer G, Debenham S, Binns M, Garcelon D, Wayne RK (2004) High MHC diversity maintained by balancing selection in an otherwise genetically monomorphic mammal. Proc Natl Acad Sci U S A 101(10):3490–3494Google Scholar
  3. Allendorf FW, Hohenlohe PA, Luikart G (2010) Genomics and the future of conservation genetics. Nat Rev Genet 11(1):697–709Google Scholar
  4. Alroy J (2015) Current extinction rates of reptiles and amphibians. Proc Natl Acad Sci U S A 112(42):13003–13008Google Scholar
  5. Andino F, Chen G, Li Z, Grayfer L, Robert J (2012) Susceptibility of Xenopus laevis tadpoles to infection by the Ranavirus frog virus 3 correlates with a reduced and delayed innate immune response in comparison with adult frogs. Virology 432(2):435–443Google Scholar
  6. Ariel E, Nicolajsen N, Christophersen MB, Holopainen R, Tapiovaara H, Jensen BB (2009) Propagation and isolation of ranaviruses in cell culture. Aquaculture 294(3–4):159–164Google Scholar
  7. Babik W (2010) Methods for MHC genotyping in non-model vertebrates. Mol Ecol Resour 10(2):237–251Google Scholar
  8. Bataille A, Cashins SD, Grogan L, Skerratt LF, Hunter D, McFadden M, Scheele B, Brannelly LA, Macris A, Harlow PS, Bell S (2015) Susceptibility of amphibians to chytridiomycosis is associated with MHC class II conformation. Proc R Soc Lond B 282(1805):20143127Google Scholar
  9. Bernatchez L, Landry C (2003) MHC studies in nonmodel vertebrates: what have we learned about natural selection in 15 years? J Evol Biol 16(3):363–377Google Scholar
  10. Boyle DG, Boyle DB, Olsen V, Morgan JAT, Hyatt AD (2004) Rapid quantitative detection of chytridiomycosis (Batrachochytrium dendrobatidis) in amphibian samples using real-time Taqman PCR assay. Dis Aquat Org 60(2):141–148Google Scholar
  11. Brand MD, Hill RD, Brenes R, Chaney JC, Wilkes RP, Grayfer L, Miller DL, Gray MJ (2016) Water temperature affects susceptibility to Ranavirus. EcoHealth 13(2):350–359Google Scholar
  12. Brown JH, Jardetzky TS, Gorga JC, Stern LJ, Urban RG, Strominger JL, Wiley DC (1993) Three-dimensional structure of the human class II histocompatibility antigen HLA-DR1. Nature 364(6432):33–39Google Scholar
  13. Brunner JL, Collins JP (2009) Testing assumptions of the trade-off theory of the evolution of parasite virulence. Evol Ecol Res 11(8):1169–1188Google Scholar
  14. Brunner JL, Beaty L, Guitard A, Russell D (2017) Heterogeneities in the infection process drive ranavirus transmission. Ecology 98(2):576–582Google Scholar
  15. Campbell LJ, Hammond SA, Price SJ, Sharma MD, Garner TWJ, Birol I, Helbing CC, Wilfert L, Griffiths AGF (2018) A novel approach to wildlife transcriptomics provides evidence of disease-mediated differential expression and changes to the microbiome of amphibian populations. Molec Ecol 27(6):1413–1427Google Scholar
  16. Chambouvet A, Gower DJ, Jirků M, Yabsley MJ, Davis AK, Leonard G, Maguire F, Doherty-Bone TM, Bittencourt-Silva GB, Wilkinson M, Richards TA (2015) Cryptic infection of a broad taxonomic and geographic diversity of tadpoles by Perkinsea protists. Proc Natl Acad Sci U S A 112(34):E4743–E4751Google Scholar
  17. Chen G, Robert J (2011) Antiviral immunity in amphibians. Viruses 3(11):2065–2086Google Scholar
  18. Chinchar VG (2002) Ranaviruses (family Iridoviridae): emerging cold-blooded killers. Arch Virol 147(3):447–470Google Scholar
  19. Chinchar VG, Waltzek TB (2014) Ranaviruses: not just for frogs. PLoS Path 10(1):e1003850Google Scholar
  20. Chinchar VG, Yu KH, Jancovich JK (2011) The molecular biology of frog virus 3 and other iridoviruses infecting cold-blooded vertebrates. Viruses 3(10):1959–1985Google Scholar
  21. Cooke GS, Hill AV (2001) Genetics of susceptibility to human infectious disease. Nat Rev Genet 2:967–977Google Scholar
  22. Cresswell P (1994) Assembly, transport, and function of MHC class II molecules. Ann Rev Immunol 12(1):259–291Google Scholar
  23. Cresswell P, Ackerman AL, Giodini A, Peaper DR, Wearsch PA (2005) Mechanisms on MHC class I-restricted antigen processing and cross-presentation. Immunol Rev 207(1):145–157Google Scholar
  24. Delport W, Poon AFY, Frost SDW, Kosakovsky Pond SL (2010) Datamonkey 2010: a suite of phylogenetic analysis tools for evolutionary biology. Bioinformatics 26(1):2455–2457Google Scholar
  25. Dengjel J, Schoor O, Fischer R, Reich M, Kraus M, Müller M, Kreymborg K, Altenberend F, Brandenburg J, Kalbacher H, Brock R (2005) Autophagy promotes MHC class II presentation of peptides from intracellular source proteins. Proc Natl Acad Sci U S A 102(22):7922–7927Google Scholar
  26. Echaubard P, Leduc J, Pauli B, Chinchar VG, Robert J, Lesbarreres D (2014) Environmental dependency of amphibian–ranavirus genotypic interactions: evolutionary perspectives on infectious diseases. Evol Appl 7(7):723–733Google Scholar
  27. Edholm ES, Saez LMA, Gill AL, Gill SR, Grayfer L, Haynes N, Myers JR, Robert J (2013) Nonclassical MHC class I-dependent invariant T cells are evolutionarily conserved and prominent from early development in amphibians. Proc Nat Acad Sci U S A 110(35):14342–14347Google Scholar
  28. Flajnik MF, Kasahara M (2001) Comparative genomics of the MHC: glimpses into the evolution of the adaptive immune system. Immunity 15(3):351–362Google Scholar
  29. Flajnik MF, Hsu E, Kaufman JF, Du Pasquier L (1987) Changes in the immune system during metomorphosis of Xenopus. Immunol Today 8(2):58–64Google Scholar
  30. Forzán MJ, Jones KM, Vanderstichel RV, Wood J, Kibenge FS, Kuiken T, Wirth W, Ariel E, Daoust PY (2015) Clinical signs, pathology and dose-dependent survival of adult wood frogs, Rana sylvatica, inoculated orally with frog virus 3 Ranavirus sp., Iridoviridae. J Gen Virol 96(5):1138–1149Google Scholar
  31. Fox J, Weisberg S (2011) An {R} companion to applied regression, 2nd edn. Sage, Thousand Oaks. URL: http://socserv.socsci.mcmaster.ca/jfox/Books/Companion. Accessed 1 Sept 2018
  32. Fu M, Waldman B (2017) Major histocompatibility complex variation and the evolution of resistance to amphibian chytridiomycosis. Immunogenetics 69(8–9):529–536Google Scholar
  33. Gantress J, Maniero GD, Cohen N, Robert J (2003) Development and characterization of a model system to study amphibian immune responses to iridoviruses. Virology 311(2):254–262Google Scholar
  34. Garland S, Baker A, Phillott AD, Skerratt LF (2010) BSA reduces inhibition in a TaqMan® assay for the detection of Batrachochytrium dendrobatidis. Dis Aquat Org 92(2–3):113–116Google Scholar
  35. Garner TW, Perkins MW, Govindarajulu P, Seglie D, Walker S, Cunningham AA, Fisher MC (2006) The emerging amphibian pathogen Batrachochytrium dendrobatidis globally infects introduced populations of the North American bullfrog, Rana catesbeiana. Biol Lett 2(3):455–459Google Scholar
  36. Gray MJ, Miller DL, Hoverman JT (2009) Ecology and pathology of amphibian ranaviruses. Dis Aquat Org 87(3):243–266Google Scholar
  37. Hedrick PW (1998) Balancing selection and MHC. Genetica 104(3):207–214Google Scholar
  38. Horner AA, Hoffman E, Hether T, Tye M, Savage AE (2017) Cryptic chytridiomycosis linked to climate and genetic variation in amphibian populations of the southeastern United States. PLoS One 12(4):e0175843Google Scholar
  39. Houlahan JE, Findlay CS, Schmidt BR, Meyer AH, Kuzmin SL (2000) Quantitative evidence for global amphibian population declines. Nature 404(6779):752–755Google Scholar
  40. Hoverman JT, Gray MJ, Haislip NA, Miller DL (2011) Phylogeny, life history, and ecology contribute to differences in amphibian susceptibility to ranaviruses. EcoHealth 8(3):301–319Google Scholar
  41. Hu W, Dong B, Kong S, Mao Y, Zheng R (2017) Pathogen resistance and gene frequency stability of major histocompatibility complex class IIB alleles in the giant spiny frog Quasipaa spinosa. Aquaculture 468(1):410–416Google Scholar
  42. Hughes AL, Nei M (1989) Nucleotide substitution at major histocompatibility complex class II loci: evidence for overdominant selection. Proc Natl Acad Sci U S A 86(3):958–962Google Scholar
  43. Isidoro-Ayza M, Lorch JM, Grear DA, Winzeler M, Calhoun DL, Barichivich WJ (2017) Pathogenic lineage of Perkinsea associated with mass mortality of frogs across the United States. Sci Rep 7(1):10288Google Scholar
  44. Jackman S (2017) pscl: classes and methods for R developed in the political science computational laboratory. United States Studies Centre, University of Sydney. Sydney, New South Wales, Australia. R package version 1.5.2. URL https://github.com/atahk/pscl/. Accessed 20 Aug 2018
  45. Jombart T, Devillard S, Balloux F (2010) Discriminant analysis of principal components: a new method for the analysis of genetically structured populations. BMC Genet 11(1):94Google Scholar
  46. Jones EY, Fugger L, Strominger JL, Siebold C (2006) MHC class II proteins and disease: a structural perspective. Nat Rev Immunol 6(4):271–282Google Scholar
  47. Karwacki EE, Atkinson MS, Ossiboff RJ, Savage AE (2018) Novel quantitative PCR assay specific for the emerging Perkinsea amphibian pathogen reveals seasonal infection dynamics. Dis Aquat Org 129(2):85–98Google Scholar
  48. Kaufman J, Salomonsen J, Flajnik M (1994) Evolutionary conservation of MHC class I and class II molecules - different yet the same. Semin Immunol 6(6):411–424Google Scholar
  49. Kearse M, Moir R, Wilson A, Stones-Havas S, Cheung M, Sturrock S, Buxton S, Cooper A, Markowitz S, Duran C, Thierer T (2012) Geneious basic: an integrated and extendable desktop software platform for the organization and analysis of sequence data. Bioinformatics 28(12):1647–1649Google Scholar
  50. Kiemnec-Tyburczy KM, Richmond JQ, Savage AE, Zamudio KR (2010) Selection, trans-species polymorphism, and locus identification of major histocompatibility complex class IIβ alleles of New World ranid frogs. Immunogenetics 62(11–12):741–751Google Scholar
  51. Klein J, Sato A, Nagl S, O'hUigín C (1998) Molecular trans-species polymorphism. Annu Rev Ecol Syst 29(1):1–21Google Scholar
  52. Kosakovsky Pond SL, Frost SD (2005) Not so different after all: a comparison of methods for detecting amino acid sites under selection. Mol Biol Evol 22(5):1208–1222Google Scholar
  53. Kosakovsky Pond SL, Frost SD, Muse SV (2005) HyPhy: hypothesis testing using phylogenies. Bioinformatics 21(1):676–679Google Scholar
  54. Kosakovsky Pond SL, Posada D, Gravenor MB, Woelk CH, Frost SDW (2006) GARD: a genetic algorithm for recombination detection. Bioinformatics 22(24):3096–3098Google Scholar
  55. Kosch TA, Bataille A, Didinger C, Eimes JA, Rodríguez-Brenes S, Ryan MJ, Waldman B (2016) Major histocompatibility complex selection dynamics in pathogen-infected túngara frog (Physalaemus pustulosus) populations. Biol Lett 12(8):20160345Google Scholar
  56. Kumar S, Stecher G, Tamura K (2016) MEGA7: molecular evolutionary genetics analysis version 7.0 for bigger datasets. Mol Biol Evol 33(7):1870–1874Google Scholar
  57. Lanfear R, Frandsen PB, Wright AM, Senfeld T, Calcott B (2016) PartitionFinder 2: new methods for selecting partitioned models of evolution for molecular and morphological phylogenetic analyses. Mol Biol Evol 34(3):772–773Google Scholar
  58. Lee-Yaw JA, Irwin JT, Green DM (2008) Postglacial range expansion from northern refugia by the wood frog, Rana sylvatica. Mol Ecol 17(3):867–884Google Scholar
  59. Lesbarrères D, Balseiro A, Brunner J, Chinchar VG, Duffus A, Kerby J, Miller DL, Robert J, Schock DM, Waltzek T, Gray MJ (2012) Ranavirus: past, present and future. Biol Lett 8(4):481–483Google Scholar
  60. Lillie M, Grueber CE, Sutton JT, Howitt R, Bishop PJ, Gleeson D, Belov K (2015) Selection on MHC class II supertypes in the New Zealand endemic Hochstetter’s frog. BMC Evol Biol 15(1):63Google Scholar
  61. Marsh IB, Whittington RJ, O’Rourke B, Hyatt AD, Chisholm O (2002) Rapid differentiation of Australian, European and American ranaviruses based on variation in major capsid protein gene sequence. Mol Cell Probes 16(2):137–151Google Scholar
  62. Matsumura M, Fremont DH, Peterson PA, Wilson IA (1992) Emerging principles for the recognition of peptide antigens by MHC class I molecules. Science 257(5072):927–934Google Scholar
  63. Miller D, Gray M, Storfer A (2011) Ecopathology of ranaviruses infecting amphibians. Viruses 3(11):2351–2373Google Scholar
  64. Morales HD, Abramowitz L, Gertz J, Sowa J, Vogel A, Robert J (2010) Innate immune responses and permissiveness to ranavirus infection of peritoneal leukocytes in the frog Xenopus laevis. J Virol 84(10):4912–4922Google Scholar
  65. Mosher BM, Grant EHC, Wiewel AW, Miller DAW, Gray MJ, Miller D (in press) Estimation of disease presence and prevalence of amphibian ranavirus. J Wild DisGoogle Scholar
  66. Mulder KP, Cortazar-Chinarro M, Harris DJ, Crottini A, Grant EHC, Fleischer RC, Savage AE (2017) Evolutionary dynamics of an expressed MHC class IIβ locus in the Ranidae (Anura) uncovered by genome walking and high-throughput amplicon sequencing. Dev Comp Immunol 76(11):177–188Google Scholar
  67. Murrell B, Moola S, Mabona A, Weighill T, Sheward D, Kosakovsky Pond SL, Scheffler K (2013) FUBAR: a fast, unconstrained Bayesian approximation for inferring selection. Mol Biol Evol 30(5):1196–1205Google Scholar
  68. Nielsen R (2005) Molecular signatures of natural selection. Ann Rev Genet 39(1):197–218Google Scholar
  69. Price SJ, Ariel E, Maclaine A, Rosa GM, Gray MJ, Brunner JL, Garner TW (2017) From fish to frogs and beyond: impact and host range of emergent ranaviruses. Virology 511(11):272–279Google Scholar
  70. Price SJ, Leung WT, Owen C, Sergeant C, Cunningham AA, Balloux F, Garner TW, Nichols RA (2018) Temperature is a key driver of a wildlife epidemic and future warming will increase impacts. bioRxiv:272369Google Scholar
  71. Raffel TR, Halstead NT, McMahon TA, Davis AK, Rohr JR (2015) Temperature variability and moisture synergistically interact to exacerbate an epizootic disease. Proc R Soc B Biol Sci 282(1801):20142039Google Scholar
  72. Robert J, George E, Andino FDJ, Chen G (2011) Waterborne infectivity of the Ranavirus frog virus 3 in Xenopus laevis. Virol 417(2):410–417Google Scholar
  73. Rojas S, Richards K, Jancovich JK, Davidson EW (2005) Influence of temperature on Ranavirus infection in larval salamanders Ambystoma tigrinum. Dis Aquat Org 63(2–3):95–100Google Scholar
  74. Rollins-Smith LA (1998) Metamorphosis and the amphibian immune system. Immunol Rev 166(1):221–230Google Scholar
  75. Rollins-Smith LA (2001) Neuroendocrine-immune system interactions in amphibians: implications for understanding global amphibian declines. Immunol Res 23(2–3):273–280Google Scholar
  76. Rollins-Smith LA, Reinert LK, Burrowes PA (2015) Coqui frogs persist with the deadly chytrid fungus despite a lack of defensive antimicrobial peptides. Dis Aquat Org 113(1):81–83Google Scholar
  77. Ronquist F, Teslenko M, Van Der Mark P, Ayres DL, Darling A, Höhna S, Larget B, Liu L, Suchard MA, Huelsenbeck JP (2012) MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space. Syst Biol 61(3):539–542Google Scholar
  78. Rousset F (2008) genepop’007: a complete re‐implementation of the genepop software for Windows and Linux. Molec Ecol Resour 8(1):103–106Google Scholar
  79. Sandberg M, Eriksson L, Jonsson J, Sjöström M, Wold S (1998) New chemical descriptors relevant for the design of biologically active peptides. A multivariate characterization of 87 amino acids. J Med Chem 41(14):2481–2491Google Scholar
  80. Savage AE, Zamudio KR (2011) MHC genotypes associate with resistance to a frog-killing fungus. Proc Natl Acad Sci U S A 108(40):16705–16710Google Scholar
  81. Savage AE, Zamudio KR (2016) Adaptive tolerance to a pathogenic fungus drives major histocompatibility complex evolution in natural amphibian populations. Proc R Soc Lond B 283(1827):20153115Google Scholar
  82. Savage AE, Becker CG, Zamudio KR (2015) Linking genetic and environmental factors in amphibian disease risk. Evol Appl 8(6):560–572Google Scholar
  83. Savage AE, Mulder KP, Torres T, Wells S (2017) Lost but not forgotten: MHC genotypes predict overwinter survival despite depauperate MHC diversity in a declining frog. Con Gen 19(2):309–322Google Scholar
  84. Schaschl H, Aitman TJ, Vyse TJ (2009) Copy number variation in the human genome and its implication in autoimmunity. Clin Exp Immunol 156(1):12–16Google Scholar
  85. Scholthof KBG (2007) The disease triangle: pathogens, the environment and society. Nat Rev Microbiol 5(2):152–156Google Scholar
  86. Shum BP, Avila D, Du Pasquier L, Kasahara M, Flajnik MF (1993) Isolation of a classical MHC class I cDNA from an amphibian : evidence for only one class I locus in the Xenopus MHC. J Immunol 151(1):5376–5386Google Scholar
  87. Siddle HV, Marzec J, Cheng Y, Jones M, Belov K (2010) MHC gene copy number variation in Tasmanian devils: implications for the spread of a contagious cancer. Proc R Soc Lond B 277(1690):2001–2006Google Scholar
  88. Smith KF, Acevedo-Whitehouse K, Pedersen AB (2009) The role of infectious diseases in biological conservation. Anim Cons 12(1):1–12Google Scholar
  89. Smith MD, Wertheim JO, Weaver S, Murrell B, Scheffler K, Kosakovsky Pond SL (2015) Less is more: an adaptive branch-site random effects model for efficient detection of episodic diversifying selection. Mol Biol Evol 32(5):1342–1353Google Scholar
  90. Sommer S (2005) The importance of immune gene variability (MHC) in evolutionary ecology and conservation. Front Zool 2(1):16Google Scholar
  91. Spielman D, Brook BW, Briscoe DA, Frankham R (2004) Does inbreeding and loss of genetic diversity decrease disease resistance? Con Gen 5(4):439–448Google Scholar
  92. Stuart SN, Chanson JS, Cox NA, Young BE, Rodrigues AS, Fischman DL, Waller RW (2004) Status and trends of amphibian declines and extinctions worldwide. Science 306(5702):1783–1786Google Scholar
  93. Stuglik MT, Radwan J, Babik W (2011) jMHC: software assistant for multilocus genotyping of gene families using next-generation amplicon sequencing. Mol Ecol Res 11(4):739–742Google Scholar
  94. Takahata N (1990) A simple genealogical structure of strongly balanced allelic lines and trans-species evolution of polymorphism. Proc Natl Acad Sci U S A 87(7):2419–2423Google Scholar
  95. Teacher AG, Garner TW, Nichols RA (2009) Evidence for directional selection at a novel major histocompatibility class I marker in wild common frogs (Rana temporaria) exposed to a viral pathogen (Ranavirus). PLoS One 4(2):e4616Google Scholar
  96. Trowsdale J (2011) The MHC, disease and selection. Immunol Lett 137(1–2):1–8Google Scholar
  97. Wake DB, Vredenburg VT (2008) Are we in the midst of the sixth mass extinction? A view from the world of amphibians. Proc Natl Acad Sci U S A 105(Suppl 1):1466–11473Google Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of BiologyUniversity of Central FloridaOrlandoUSA
  2. 2.Center for Conservation Genomics, Smithsonian Conservation Biology InstituteNational Zoological ParkWashingtonUSA
  3. 3.United States Geological Survey, Patuxent Wildlife Research Center, SO Conte Anadromous Fish Research LabTurner FallsUSA
  4. 4.CIBIO/InBIO, Research Center in Biodiversity and Genetic ResourcesVairãoPortugal
  5. 5.Departamento de Biologia da Faculdade de Ciencias da Universidade do PortoPortoPortugal

Personalised recommendations