title: More than skin deep: functional genomic basis for resistance to amphibian chytridiomycosis.
abstract: The amphibian-killing chytrid fungus Batrachochytrium dendrobatidis (Bd) is one of the most generalist pathogens known, capable of infecting hundreds of species globally and causing widespread population declines and extinctions. However, some host species are seemingly unaffected by Bd, tolerating or clearing infections without clinical signs of disease. Variation in host immune responses is commonly evoked for these resistant or tolerant species, yet to date, we have no direct comparison of amphibian species responses to infection at the level of gene expression. In this study, we challenged four Central American frog species that vary in Bd susceptibility, with a sympatric virulent strain of the pathogen. We compared skin and spleen orthologous gene expression using differential expression tests and coexpression gene network analyses. We found that resistant species have reduced skin inflammatory responses and increased expression of genes involved in skin integrity. In contrast, only highly susceptible species exhibited suppression of splenic T-cell genes. We conclude that resistance to chytridiomycosis may be related to a species' ability to escape the immunosuppressive activity of the fungus. Moreover, our results indicate that within-species differences in splenic proteolytic enzyme gene expression may contribute to intraspecific variation in survival. This first comparison of amphibian functional immunogenomic architecture in response to Bd provides insights into key genetic mechanisms underlying variation in disease outcomes among amphibian species.
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University are35@cornell.edu.
authors.forename: Amy R
authors.initials: AR
authors.lastname: Ellison
authors.affiliation: Department of Biology, University of Maryland, College Park.
authors.forename: Tate
authors.initials: T
authors.lastname: Tunstall
authors.affiliation: Department of Biology, University of Maryland, College Park.
authors.forename: Graziella V
authors.initials: GV
authors.lastname: DiRenzo
authors.affiliation: Department of Biological Sciences, Virginia Tech.
authors.forename: Myra C
authors.initials: MC
authors.lastname: Hughey
authors.affiliation: Department of Biology, James Madison University.
authors.forename: Eria A
authors.initials: EA
authors.lastname: Rebollar
authors.affiliation: Department of Biological Sciences, Virginia Tech.
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Belden
authors.affiliation: Department of Biology, James Madison University.
authors.forename: Reid N
authors.initials: RN
authors.lastname: Harris
authors.affiliation: Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panamá
authors.forename: Roberto
authors.initials: R
authors.lastname: Ibáñez
authors.affiliation: Department of Biology, University of Maryland, College Park.
authors.forename: Karen R
authors.initials: KR
authors.lastname: Lips
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University.
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Zamudio
mesh_terms: D000818:Animals; D001001:Anura / Q000235:genetics* / Q000382:microbiology; D008411:Chytridiomycota / Q000472:pathogenicity*; D060467:Disease Resistance / Q000235:genetics*; D005786:Gene Expression Regulation; D053263:Gene Regulatory Networks; D023281:Genomics; D010447:Peptide Hydrolases / Q000096:biosynthesis / Q000235:genetics; D012867:Skin / Q000201:enzymology / Q000382:microbiology; D013154:Spleen / Q000201:enzymology
chemical_list: D010447:Peptide Hydrolases
keywords: Batrachochytrium dendrobatidis; amphibian immunity; comparative transcriptomics; immunogenomics; immunosuppression