101
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Casais R, Larrinaga AR, Dalton KP, Domínguez Lapido P, Márquez I, Bécares E, Carter ED, Gray MJ, Miller DL, Balseiro A. Water sports could contribute to the translocation of ranaviruses. Sci Rep 2019; 9:2340. [PMID: 30787411 PMCID: PMC6382805 DOI: 10.1038/s41598-019-39674-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 01/28/2019] [Indexed: 02/05/2023] Open
Abstract
Ranaviruses have been identified as the cause of explosive disease outbreaks in amphibians worldwide and can be transmitted between hosts both via direct and indirect contact, in which humans might contribute to the translocation of contaminated material. The aim of this study was to evaluate the possible role of water sports in the human translocation of ranavirus, Batrachochytrium dendrobatidis (Bd), and B. salamandrivorans (Bsal). A total of 234 boats were sampled during the spring Spanish Canoe Championship which took place in Pontillón de Castro, a reservoir with a history of ranavirosis, in May 2017. Boats were tested for the presence of ranavirus and Batrachochytrium spp. DNA, using quantitative real-time polymerase chain reaction techniques (qPCR). A total of 22 swabs (22/234, 9.40%) yielded qPCR-positive results for Ranavirus DNA while Bd or Bsal were not detected in any of the samples. We provide the first evidence that human-related water sports could be a source of ranavirus contamination, providing justification for public disinfecting stations in key areas where human traffic from water sports is high.
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Affiliation(s)
- Rosa Casais
- SERIDA, Servicio Regional de Investigación y Desarrollo Agroalimentario, Gijón, Asturias, Spain
| | | | - Kevin P Dalton
- Departamento de Bioquímica, Universidad de Oviedo, Oviedo, Spain
| | | | - Isabel Márquez
- SERIDA, Servicio Regional de Investigación y Desarrollo Agroalimentario, Gijón, Asturias, Spain
| | - Eloy Bécares
- Facultad de Biología, Universidad de León, Campus de Vegazana, León, Spain
| | - E Davis Carter
- Center for Wildlife Health, University of Tennessee Institute of Agriculture, Knoxville, Tennessee, United States of America
| | - Matthew J Gray
- Center for Wildlife Health, University of Tennessee Institute of Agriculture, Knoxville, Tennessee, United States of America
| | - Debra L Miller
- Center for Wildlife Health, University of Tennessee Institute of Agriculture, Knoxville, Tennessee, United States of America
| | - Ana Balseiro
- SERIDA, Servicio Regional de Investigación y Desarrollo Agroalimentario, Gijón, Asturias, Spain.
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102
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Helbing CC, Hammond SA, Jackman SH, Houston S, Warren RL, Cameron CE, Birol I. Antimicrobial peptides from Rana [Lithobates] catesbeiana: Gene structure and bioinformatic identification of novel forms from tadpoles. Sci Rep 2019; 9:1529. [PMID: 30728430 PMCID: PMC6365531 DOI: 10.1038/s41598-018-38442-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 12/28/2018] [Indexed: 01/21/2023] Open
Abstract
Antimicrobial peptides (AMPs) exhibit broad-spectrum antimicrobial activity, and have promise as new therapeutic agents. While the adult North American bullfrog (Rana [Lithobates] catesbeiana) is a prolific source of high-potency AMPs, the aquatic tadpole represents a relatively untapped source for new AMP discovery. The recent publication of the bullfrog genome and transcriptomic resources provides an opportune bridge between known AMPs and bioinformatics-based AMP discovery. The objective of the present study was to identify novel AMPs with therapeutic potential using a combined bioinformatics and wet lab-based approach. In the present study, we identified seven novel AMP precursor-encoding transcripts expressed in the tadpole. Comparison of their amino acid sequences with known AMPs revealed evidence of mature peptide sequence conservation with variation in the prepro sequence. Two mature peptide sequences were unique and demonstrated bacteriostatic and bactericidal activity against Mycobacteria but not Gram-negative or Gram-positive bacteria. Nine known and seven novel AMP-encoding transcripts were detected in premetamorphic tadpole back skin, olfactory epithelium, liver, and/or tail fin. Treatment of tadpoles with 10 nM 3,5,3'-triiodothyronine for 48 h did not affect transcript abundance in the back skin, and had limited impact on these transcripts in the other three tissues. Gene mapping revealed considerable diversity in size (1.6-15 kbp) and exon number (one to four) of AMP-encoding genes with clear evidence of alternative splicing leading to both prepro and mature amino acid sequence diversity. These findings verify the accuracy and utility of the bullfrog genome assembly, and set a firm foundation for bioinformatics-based AMP discovery.
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Affiliation(s)
- Caren C Helbing
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, V8P 5C2, Canada.
| | - S Austin Hammond
- Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, V5Z 4S6, Canada
| | - Shireen H Jackman
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, V8P 5C2, Canada
| | - Simon Houston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, V8P 5C2, Canada
| | - René L Warren
- Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, V5Z 4S6, Canada
| | - Caroline E Cameron
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, V8P 5C2, Canada
| | - Inanç Birol
- Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, V5Z 4S6, Canada
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103
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Robak MJ, Reinert LK, Rollins-Smith LA, Richards-Zawacki CL. Out in the cold and sick: Low temperatures and fungal infections impair a frog's skin defenses. J Exp Biol 2019; 222:jeb.209445. [DOI: 10.1242/jeb.209445] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 09/02/2019] [Indexed: 12/29/2022]
Abstract
Amphibians worldwide continue to battle an emerging infectious disease, chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd). Southern leopard frogs, Rana sphenocephala, are known to become infected with this pathogen, yet they are considered ‘of least concern’ for declines due to chytridiomycosis. Previous studies have shown that R. sphenocephala secretes four antimicrobial peptides (AMPs) onto their skin which may play an important role in limiting susceptibility to chytridiomycosis. Here we examined the (1) effects of temperature and AMP depletion on infections with Bd and (2) effects of temperature and Bd infection on the capacity to secrete AMPs in juvenile leopard frogs. Pathogen burden and mortality were greater in frogs exposed to Bd at low temperature but did not increase following monthly AMP depletion. Both low temperature and Bd exposure reduced the capacity of juvenile frogs to restore peptides after monthly depletions. Frogs held at 14°C were poorly able to restore peptides in comparison with those at 26 °C. Frogs held at 26 °C were better able to restore their peptides, but when exposed to Bd, this capacity was significantly reduced. These results strongly support the hypothesis that both colder temperatures and Bd infections impair the capacity of juvenile frogs to produce and secrete AMPs, an important component of their innate defense against chytrid fungi and other pathogens. Thus, in the face of unpredictable climate changes and enzootic pathogens, assessments of disease risk should consider the potential for effects of environmental variation and pathogen exposure on the quality of host defenses.
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Affiliation(s)
- Matthew J. Robak
- Department of Ecology & Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA
| | - Laura K. Reinert
- Department of Pathology, Microbiology and Immunology Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Louise A. Rollins-Smith
- Department of Pathology, Microbiology and Immunology Vanderbilt University School of Medicine, Nashville, TN 37232, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Corinne L. Richards-Zawacki
- Department of Ecology & Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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104
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Lei XP, Yi G, Wang KY, OuYang P, Chen DF, Huang XL, Huang C, Lai WM, Zhong ZJ, Huo CL, Yang ZX. Elizabethkingia miricolainfection in Chinese spiny frog (Quasipaa spinosa). Transbound Emerg Dis 2018; 66:1049-1053. [DOI: 10.1111/tbed.13101] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 11/24/2018] [Accepted: 12/07/2018] [Indexed: 01/18/2023]
Affiliation(s)
- Xue Ping Lei
- College of Veterinary Medicine Sichuan Agricultural University Wenjiang Sichuan China
| | - Geng Yi
- College of Veterinary Medicine Sichuan Agricultural University Wenjiang Sichuan China
| | - Kai Yu Wang
- College of Veterinary Medicine Sichuan Agricultural University Wenjiang Sichuan China
| | - Ping OuYang
- College of Veterinary Medicine Sichuan Agricultural University Wenjiang Sichuan China
| | - De Fang Chen
- Department of Aquaculture Sichuan Agricultural University Wenjiang Sichuan China
| | - Xiao Li Huang
- Department of Aquaculture Sichuan Agricultural University Wenjiang Sichuan China
| | - Chao Huang
- College of Veterinary Medicine Sichuan Agricultural University Wenjiang Sichuan China
| | - Wei Min Lai
- College of Veterinary Medicine Sichuan Agricultural University Wenjiang Sichuan China
| | - Zi Jun Zhong
- College of Veterinary Medicine Sichuan Agricultural University Wenjiang Sichuan China
| | - Chang Liang Huo
- College of Veterinary Medicine Sichuan Agricultural University Wenjiang Sichuan China
| | - Ze Xiao Yang
- College of Veterinary Medicine Sichuan Agricultural University Wenjiang Sichuan China
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105
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Barsotti AMG, Titon Junior B, Titon SCM, Gomes FR. Dehydration as a stressor in toads (Rhinella ornata
). JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2018; 331:168-174. [DOI: 10.1002/jez.2250] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 11/30/2018] [Accepted: 11/30/2018] [Indexed: 01/02/2023]
Affiliation(s)
| | - Braz Titon Junior
- Departamento de Fisiologia; Instituto de Biociências, Universidade de São Paulo; São Paulo Brazil
| | | | - Fernando Ribeiro Gomes
- Departamento de Fisiologia; Instituto de Biociências, Universidade de São Paulo; São Paulo Brazil
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106
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Liu J, Chen Z, Chen G, Wang B, Jiang J. Skin innate immunity of diskless-fingered odorous frogs (Odorrana grahami) with spatial-temporal variations. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 89:23-30. [PMID: 30092315 DOI: 10.1016/j.dci.2018.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 08/05/2018] [Accepted: 08/05/2018] [Indexed: 06/08/2023]
Abstract
The skin innate immunities of diskless-fingered odorous frogs (Odorrana grahami) from three populations were investigated. The antimicrobial capacities of skin secretions against the 60 representative environmental bacterial strains were evaluated using the values of the minimum inhibitory concentration (MIC) equivalents, which were defined as the volumes of antimicrobial solution just inhibiting the tested bacteria per 1 cm2 of surface area, from 0.06 to 9.10 mL/cm2. Our results revealed significantly different skin antimicrobial capacities among the three populations: Mianning < Huili < Kunming. Within the frog population, the skin antimicrobial capacities are highly variable depending on the season: in Mianning frogs, summer < autumn and spring; in Huili frogs, spring < autumn < summer; in Kunming frogs, autumn < spring < summer. The animal density and body mass significantly impacted the skin antimicrobial capacity, while the sex ratio and soil or water bacterial counts did not.
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Affiliation(s)
- Jiongyu Liu
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, China.
| | - Zhenyong Chen
- College of Life Science, China West Normal University, Nanchong 637009, China
| | - Guiying Chen
- Department of Biology, Sichuan Normal University, Chengdu 610101, China
| | - Bin Wang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, China
| | - Jianping Jiang
- CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, China.
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107
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Watters JL, Davis DR, Yuri T, Siler CD. Concurrent Infection of Batrachochytrium dendrobatidis and Ranavirus among Native Amphibians from Northeastern Oklahoma, USA. JOURNAL OF AQUATIC ANIMAL HEALTH 2018; 30:291-301. [PMID: 30290015 DOI: 10.1002/aah.10041] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 07/22/2018] [Indexed: 06/08/2023]
Abstract
Global amphibian decline continues to be a great concern despite our increased understanding of the causes behind the observed patterns of the decline, such as habitat modification and infectious diseases. Although there is a large body of literature on the topic of amphibian infectious diseases, pathogen prevalence and distribution among entire communities of species in many regions remain poorly understood. In addition to these geographic gaps in our understanding, past work has focused largely on individual pathogens, either Batrachochytrium dendrobatidis (Bd) or ranavirus (RV), rather than dual infection rates among host species. We sampled for prevalence and infection load of both pathogens in 514 amphibians across 16 total sites in northeastern Oklahoma. Amphibians were caught by hand, net, or seine; they were swabbed to screen for Bd; and liver tissue samples were collected to screen for RV. Overall results of quantitative PCR assays showed that 7% of screened individuals were infected with RV only, 37% were infected with Bd only, and 9% were infected with both pathogens simultaneously. We also documented disease presence in several rare amphibian species that are currently being monitored as species of concern due to their small population sizes in Oklahoma. This study synthesizes a growing body of research regarding infectious diseases among amphibian communities in the central United States.
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Affiliation(s)
- Jessa L Watters
- Sam Noble Oklahoma Museum of Natural History, University of Oklahoma, 2401 Chautauqua Avenue, Norman, Oklahoma, 73072-7029, USA
| | - Drew R Davis
- Department of Biology, University of South Dakota, 414 East Clark Street, Vermillion, South Dakota, 57069, USA
| | - Tamaki Yuri
- Sam Noble Oklahoma Museum of Natural History, University of Oklahoma, 2401 Chautauqua Avenue, Norman, Oklahoma, 73072-7029, USA
| | - Cameron D Siler
- Sam Noble Oklahoma Museum of Natural History, University of Oklahoma, 2401 Chautauqua Avenue, Norman, Oklahoma, 73072-7029, USA
- Department of Biology, University of Oklahoma, 730 Van Vleet Oval, Norman, Oklahoma, 73019, USA
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108
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Endocrine and immune responses of larval amphibians to trematode exposure. Parasitol Res 2018; 118:275-288. [DOI: 10.1007/s00436-018-6154-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Accepted: 11/12/2018] [Indexed: 11/26/2022]
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109
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Grogan LF, Robert J, Berger L, Skerratt LF, Scheele BC, Castley JG, Newell DA, McCallum HI. Review of the Amphibian Immune Response to Chytridiomycosis, and Future Directions. Front Immunol 2018; 9:2536. [PMID: 30473694 PMCID: PMC6237969 DOI: 10.3389/fimmu.2018.02536] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 10/15/2018] [Indexed: 12/27/2022] Open
Abstract
The fungal skin disease, chytridiomycosis (caused by Batrachochytrium dendrobatidis and B. salamandrivorans), has caused amphibian declines and extinctions globally since its emergence. Characterizing the host immune response to chytridiomycosis has been a focus of study with the aim of disease mitigation. However, many aspects of the innate and adaptive arms of this response are still poorly understood, likely due to the wide range of species' responses to infection. In this paper we provide an overview of expected immunological responses (with inference based on amphibian and mammalian immunology), together with a synthesis of current knowledge about these responses for the amphibian-chytridiomycosis system. We structure our review around four key immune stages: (1) the naïve immunocompetent state, (2) immune defenses that are always present (constitutive defenses), (3) mechanisms for recognition of a pathogen threat and innate immune defenses, and (4) adaptive immune responses. We also evaluate the current hot topics of immunosuppression and immunopathology in chytridiomycosis, and discuss their respective roles in pathogenesis. Our synthesis reveals that susceptibility to chytridiomycosis is likely to be multifactorial. Susceptible amphibians appear to have ineffective constitutive and innate defenses, and a late-stage response characterized by immunopathology and Bd-induced suppression of lymphocyte responses. Overall, we identify substantial gaps in current knowledge, particularly concerning the entire innate immune response (mechanisms of initial pathogen detection and possible immunoevasion by Bd, degree of activation and efficacy of the innate immune response, the unexpected absence of innate leukocyte infiltration, and the cause and role of late-stage immunopathology in pathogenesis). There are also gaps concerning most of the adaptive immune system (the relative importance of B and T cell responses for pathogen clearance, the capacity and extent of immunological memory, and specific mechanisms of pathogen-induced immunosuppression). Improving our capacity for amphibian immunological research will require selection of an appropriate Bd-susceptible model species, the development of taxon-specific affinity reagents and cell lines for functional assays, and the application of a suite of conventional and emerging immunological methods. Despite current knowledge gaps, immunological research remains a promising avenue for amphibian conservation management.
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Affiliation(s)
- Laura F Grogan
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, QLD, Australia
| | - Jacques Robert
- University of Rochester Medical Center, Rochester, NY, United States
| | - Lee Berger
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia.,Faculty of Veterinary and Agricultural Sciences, Melbourne Veterinary School, University of Melbourne, Werribee, VIC, Australia
| | - Lee F Skerratt
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, QLD, Australia.,Faculty of Veterinary and Agricultural Sciences, Melbourne Veterinary School, University of Melbourne, Werribee, VIC, Australia
| | - Benjamin C Scheele
- Fenner School of Environment and Society, The Australian National University, Canberra, ACT, Australia.,Threatened Species Recovery Hub, National Environmental Science Program, Fenner School of Environment and Society, The Australian National University, Canberra, ACT, Australia
| | - J Guy Castley
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, QLD, Australia
| | - David A Newell
- Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW, Australia
| | - Hamish I McCallum
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Nathan, QLD, Australia
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110
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Gardner S, Assis VR, Zhao H, Gomes FR, Peatman E, Mendonça MT. Differential gene expression to an LPS challenge in relation to exogenous corticosterone in the invasive cane toad (Rhinella marina). DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 88:114-123. [PMID: 30030104 DOI: 10.1016/j.dci.2018.07.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 07/16/2018] [Accepted: 07/16/2018] [Indexed: 06/08/2023]
Abstract
The cane toad (Rhinella marina) is an invasive amphibian in several parts of the world. Much of the research performed on assessing the dispersal potential of invasive species has focused immunity. Invaders are predicted to rely less on pro-inflammatory immunity, allowing them to allocate energy to dispersal. Elevated stress may play a role in regulation of immune responses used by invasive species. RNA sequencing of spleen tissue from cane toads subjected to an acute LPS challenge revealed genes coding for cytokines involved in typical innate responses such as phagocytic cell recruitment, extravasation, inflammation, and lymphocyte differentiation were significantly upregulated, while toads receiving transdermal application of corticosterone in addition to an LPS injection showed downregulation of genes involved with cell mediated immunity. These results indicate hormonal changes associated with acute stress may alter investment into mounting cell-mediated or humoral responses while allowing for prolonged phagocytic innate responses in this invasive species.
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Affiliation(s)
- Steven Gardner
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, 350 South College St, Auburn, AL 36849, USA.
| | - Vania Regina Assis
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, 05508-900, São Paulo, SP, Brazil.
| | - Honggang Zhao
- School of Fisheries, Aquaculture, and Aquatic Sciences, 377 CASIC Bldg, Auburn University, Auburn, AL 36849, USA.
| | - Fernando Ribeiro Gomes
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, 05508-900, São Paulo, SP, Brazil.
| | - Eric Peatman
- School of Fisheries, Aquaculture, and Aquatic Sciences, 377 CASIC Bldg, Auburn University, Auburn, AL 36849, USA.
| | - Mary T Mendonça
- Department of Biological Sciences, Auburn University, 331 Funchess Hall, 350 South College St, Auburn, AL 36849, USA.
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111
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Kärvemo S, Meurling S, Berger D, Höglund J, Laurila A. Effects of host species and environmental factors on the prevalence of Batrachochytrium dendrobatidis in northern Europe. PLoS One 2018; 13:e0199852. [PMID: 30359384 PMCID: PMC6201871 DOI: 10.1371/journal.pone.0199852] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/09/2018] [Indexed: 11/18/2022] Open
Abstract
The fungal pathogen Batrachochytrium dendrobatidis (Bd) poses a major threat to amphibian populations. To assist efforts to address such threats, we examined differences in Bd host infection prevalence among amphibian species and its relations to both local environmental factors in breeding habitats and landscape variables measured at three scales (500, 2000 and 5000 m radii) around breeding sites in southernmost Sweden. We sampled 947 anurans of six species in 31 ponds and assessed their infection status. We then examined correlations of infection prevalence with canopy cover, pond perimeter and pH (treated as local-scale pond characteristics), and the number of ponds, area of arable land, area of mature forest, number of resident people and presence of sea within the three radii (treated as landscape variables). The Bd infection prevalence was very low, 0.5–1.0%, in two of the six anuran species (Bufo bufo and Rana temporaria), and substantially higher (13–64%) in the other four (Bombina bombina, Bufotes variabilis, Epidalea calamita, Rana arvalis). In the latter four species Bd infection prevalence was positively associated with ponds’ pH (site range: 5.3–8.1), and negatively associated with areas of mature forest and/or wetlands in the surroundings. Our results show that the infection dynamics of Bd are complex and associated with host species, local pond characteristics and several landscape variables at larger spatial scales. Knowledge of environmental factors associated with Bd infections and differences in species’ susceptibility may help to counter further spread of the disease and guide conservation action plans, especially for the most threatened species.
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Affiliation(s)
- Simon Kärvemo
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
- * E-mail:
| | - Sara Meurling
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
| | - David Berger
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
| | - Jacob Höglund
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
| | - Anssi Laurila
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
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112
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Abstract
Human-mediated disease outbreaks due to poor biosecurity practices when processing animals in wild populations have been suspected. We tested whether not changing nitrile gloves between processing wood frog (Lithobates sylvaticus) tadpoles and co-housing individuals increased pathogen transmission and subsequent diseased-induced mortality caused by the emerging pathogen, ranavirus. We found that not changing gloves between processing infected and uninfected tadpoles resulted in transmission of ranavirus and increased the risk of mortality of uninfected tadpoles by 30X. Co-housing tadpoles for only 15 minutes with 10% of individuals infected resulted in ranavirus transmission and 50% mortality of uninfected tadpoles. More extreme mortality was observed when the co-housing infection prevalence was >10%. Our results illustrate that human-induced disease outbreaks due to poor biosecurity practices are possible in wild animal populations.
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113
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UV-B affects the immune system and promotes nuclear abnormalities in pigmented and non-pigmented bullfrog tadpoles. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2018; 180:109-117. [DOI: 10.1016/j.jphotobiol.2018.01.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 01/12/2018] [Accepted: 01/17/2018] [Indexed: 01/12/2023]
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114
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Wu NC, Cramp RL, Franklin CE. Body size influences energetic and osmoregulatory costs in frogs infected with Batrachochytrium dendrobatidis. Sci Rep 2018; 8:3739. [PMID: 29487313 PMCID: PMC5829222 DOI: 10.1038/s41598-018-22002-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 02/06/2018] [Indexed: 12/18/2022] Open
Abstract
Sloughing maintains the skins integrity and critical functionality in amphibians. Given the behavioural, morphological and osmoregulatory changes that accompany sloughing, this process is likely to be physiologically costly. Chytridiomycosis, a cutaneous disease of amphibians caused by the fungus Batrachochytrium dendrobatidis (Bd), disrupts skin function and increases sloughing rates. Moreover, mortality rates from chytridiomycosis are significantly higher in juveniles and so we hypothesised that smaller individuals maybe more susceptible to chytridiomycosis because of allometric scaling effects on the energetic and osmoregulatory costs of sloughing. We measured in-vivo cutaneous ion loss rates and whole animal metabolic rate (MR) of Green tree frogs, Litoria caerulea, over a range of body sizes both infected and uninfected frogs during sloughing. Infected animals had a greater rate of ion loss and mass-specific MR during non-sloughing periods but there were no additional effects of sloughing on either of these parameters. There were also significant interactions with body size and Bd load indicating that smaller animals with higher Bd loads have greater rates of ion loss and higher energetic demands. Our results shed light on why smaller Bd-infected anurans often exhibit greater physiological disruption than larger individuals.
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Affiliation(s)
- Nicholas C Wu
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Rebecca L Cramp
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Craig E Franklin
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, 4072, Australia.
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115
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Santymire RM, Manjerovic MB, Sacerdote-Velat A. A novel method for the measurement of glucocorticoids in dermal secretions of amphibians. CONSERVATION PHYSIOLOGY 2018; 6:coy008. [PMID: 29479435 PMCID: PMC5814794 DOI: 10.1093/conphys/coy008] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 01/19/2018] [Accepted: 02/05/2018] [Indexed: 05/23/2023]
Abstract
Amphibians have been declining in both diversity and abundance due in large part to habitat degradation and the prevalence of emerging diseases. Although stressors can suppress the immune system, affecting an individual's health and susceptibility to pathogens, established methods for directly collecting stress hormones are not suitable for rapid field use or for use on threatened and endangered species. To overcome these challenges, we are developing an innovative method to collect and measure amphibian glucocorticoid secretions using non-invasive dermal swabs. We tested this methodology using multiple terrestrial, semi-aquatic and fully aquatic species. We swabbed the dorsal side of each animal six times and then induced a stressor of either hand-restraint, ACTH injection, or saline as a control. We then repeated swab collection immediately after the stressor and at 15, 30, 45, 60, 90 and 120 min intervals. Cortisol enzyme immunoassay detected changes in cortisol post-stressor. We also tested this methodology in the field and were successfully able to detect glucocorticoids from multiple species at varying life stages. When using in the field, capture technique should be considered since it may impact stress levels in certain species. Upon further testing, this novel method may be used to greatly increase our understanding of amphibian health especially as disease and environmental changes continue to impact fragile populations.
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Affiliation(s)
- R M Santymire
- Lincoln Park Zoo, Conservation & Science Department, 2001 N. Clark St., Chicago, IL 60614, USA
| | - M B Manjerovic
- Lincoln Park Zoo, Conservation & Science Department, 2001 N. Clark St., Chicago, IL 60614, USA
- Department of Biology, Virginia Military Institute, 301C Maury-Brooke Hall, Lexington, VA 24450, USA
| | - A Sacerdote-Velat
- The Chicago Academy of Sciences, Peggy Notebaert Nature Museum, 2430 North Cannon Drive, Chicago, IL 60614, USA
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116
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Eskew EA, Shock BC, LaDouceur EEB, Keel K, Miller MR, Foley JE, Todd BD. Gene expression differs in susceptible and resistant amphibians exposed to Batrachochytrium dendrobatidis. ROYAL SOCIETY OPEN SCIENCE 2018; 5:170910. [PMID: 29515828 PMCID: PMC5830717 DOI: 10.1098/rsos.170910] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Chytridiomycosis, the disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), has devastated global amphibian biodiversity. Nevertheless, some hosts avoid disease after Bd exposure even as others experience near-complete extirpation. It remains unclear whether the amphibian adaptive immune system plays a role in Bd defence. Here, we describe gene expression in two host species-one susceptible to chytridiomycosis and one resistant-following exposure to two Bd isolates that differ in virulence. Susceptible wood frogs (Rana sylvatica) had high infection loads and mortality when exposed to the more virulent Bd isolate but lower infection loads and no fatal disease when exposed to the less virulent isolate. Resistant American bullfrogs (R. catesbeiana) had high survival across treatments and rapidly cleared Bd infection or avoided infection entirely. We found widespread upregulation of adaptive immune genes and downregulation of important metabolic and cellular maintenance components in wood frogs after Bd exposure, whereas American bullfrogs showed little gene expression change and no evidence of an adaptive immune response. Wood frog responses suggest that adaptive immune defences may be ineffective against virulent Bd isolates that can cause rapid physiological dysfunction. By contrast, American bullfrogs exhibited robust resistance to Bd that is likely attributable, at least in part, to their continued upkeep of metabolic and skin integrity pathways as well as greater antimicrobial peptide expression compared to wood frogs, regardless of exposure. Greater understanding of these defences will ultimately help conservationists manage chytridiomycosis.
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Affiliation(s)
- Evan A. Eskew
- Graduate Group in Ecology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
- EcoHealth Alliance, 460 West 34th Street – 17th Floor, New York, NY 10001, USA
- Author for correspondence: Evan A. Eskew e-mail:
| | - Barbara C. Shock
- Department of Biology, Lincoln Memorial University, 6965 Cumberland Gap Parkway, Harrogate, TN 37752, USA
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | | | - Kevin Keel
- Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Michael R. Miller
- Department of Animal Science, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Janet E. Foley
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Brian D. Todd
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
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117
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Cramp RL, Franklin CE. Exploring the link between ultraviolet B radiation and immune function in amphibians: implications for emerging infectious diseases. CONSERVATION PHYSIOLOGY 2018; 6:coy035. [PMID: 29992023 PMCID: PMC6022628 DOI: 10.1093/conphys/coy035] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 05/27/2018] [Accepted: 06/07/2018] [Indexed: 05/07/2023]
Abstract
Amphibian populations the world over are under threat of extinction, with as many as 40% of assessed species listed as threatened under IUCN Red List criteria (a significantly higher proportion than other vertebrate group). Amongst the key threats to amphibian species is the emergence of novel infectious diseases, which have been implicated in the catastrophic amphibian population declines and extinctions seen in many parts of the world. The recent emergence of these diseases coincides with increased ambient levels of ultraviolet B radiation (UVBR) due to anthropogenic thinning of the Earth's protective ozone layer, raising questions about potential interactions between UVBR exposure and disease in amphibians. While reasonably well documented in other vertebrate groups (particularly mammals), the immunosuppressive capacity of UVBR and the potential for it to influence disease outcomes has been largely overlooked in amphibians. Herein, we review the evidence for UVBR-associated immune system disruption in amphibians and identify a number of direct and indirect pathways through which UVBR may influence immune function and disease susceptibility in amphibians. By exploring the physiological mechanisms through which UVBR may affect host immune function, we demonstrate how ambient UVBR could increase amphibian susceptibility to disease. We conclude by discussing the potential implications of elevated UVBR for inter and intraspecific differences in disease dynamics and discuss how future research in this field may be directed to improve our understanding of the role that UVBR plays in amphibian immune function.
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Affiliation(s)
- Rebecca L Cramp
- School of Biological Sciences, The University of Queensland, Goddard Building (8), St Lucia, Queensland, Australia
- Corresponding author: School of Biological Sciences, The University of Queensland, Goddard Building (8), St Lucia, Queensland 4072, Australia.
| | - Craig E Franklin
- School of Biological Sciences, The University of Queensland, Goddard Building (8), St Lucia, Queensland, Australia
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118
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Gauberg J, Wu N, Cramp RL, Kelly SP, Franklin CE. A lethal fungal pathogen directly alters tight junction proteins in the skin of a susceptible amphibian. J Exp Biol 2018; 222:jeb.192245. [DOI: 10.1242/jeb.192245] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 12/05/2018] [Indexed: 01/01/2023]
Abstract
Bacterial and viral pathogens can weaken epithelial barriers by targeting and disrupting tight junction (TJ) proteins. Comparatively, however, little is known about the direct effects of fungal pathogens on TJ proteins and their expression. The disease, chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is threatening amphibian populations worldwide. Bd is known to infect amphibian skin and disrupt cutaneous osmoregulation. However, exactly how this occurs is poorly understood. This study considered the impact of Bd infection on the barrier properties of the Australian green tree frog (Litoria caerulea) epidermis by examining how inoculation of animals with Bd influenced the paracellular movement of FITC-dextran (4 kDa, FD-4) across the skin in association with alterations in the mRNA and protein abundance of select TJ proteins of the epidermal TJ complex. It was observed that Bd infection increased paracellular movement of FD-4 across the skin linearly with fungal infection load. In addition, Bd infection increased transcript abundance of the tricellular TJ (tTJ) protein tricellulin (tric) as well as the bicellular TJ (bTJ) proteins occludin (ocln), claudin (cldn) -1, -4 and the scaffolding TJ protein zonula occludens-1 (zo-1). However, while Tric protein abundance increased in accord with changes in transcript abundance, protein abundance of Cldn-1 was significantly reduced and Ocln protein abundance was unchanged. Data indicate that disruption of cutaneous osmoregulation in L. caerulea following Bd infection occurs, at least in part, by an increase in epidermal paracellular permeability in association with compromised integrity of the epidermal TJ complex.
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Affiliation(s)
- J. Gauberg
- School of Biological Sciences, The University of Queensland, Brisbane, QLD, Australia
- Department of Biology, York University, Toronto, ON, Canada
| | - N. Wu
- School of Biological Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - R. L. Cramp
- School of Biological Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - S. P. Kelly
- Department of Biology, York University, Toronto, ON, Canada
| | - C. E. Franklin
- School of Biological Sciences, The University of Queensland, Brisbane, QLD, Australia
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119
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Kirschman LJ, Crespi EJ, Warne RW. Critical disease windows shaped by stress exposure alter allocation trade‐offs between development and immunity. J Anim Ecol 2017; 87:235-246. [DOI: 10.1111/1365-2656.12778] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 10/20/2017] [Indexed: 02/06/2023]
Affiliation(s)
| | - Erica J. Crespi
- School of Biological SciencesWashington State University Pullman WA USA
| | - Robin W. Warne
- Department of ZoologySouthern Illinois University Carbondale IL USA
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120
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Mulder KP, Cortazar-Chinarro M, Harris DJ, Crottini A, Campbell Grant EH, Fleischer RC, Savage AE. Evolutionary dynamics of an expressed MHC class IIβ locus in the Ranidae (Anura) uncovered by genome walking and high-throughput amplicon sequencing. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 76:177-188. [PMID: 28587861 DOI: 10.1016/j.dci.2017.05.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 05/30/2017] [Accepted: 05/30/2017] [Indexed: 06/07/2023]
Abstract
The Major Histocompatibility Complex (MHC) is a genomic region encoding immune loci that are important and frequently used markers in studies of adaptive genetic variation and disease resistance. Given the primary role of infectious diseases in contributing to global amphibian declines, we characterized the hypervariable exon 2 and flanking introns of the MHC Class IIβ chain for 17 species of frogs in the Ranidae, a speciose and cosmopolitan family facing widespread pathogen infections and declines. We find high levels of genetic variation concentrated in the Peptide Binding Region (PBR) of the exon. Ten codons are under positive selection, nine of which are located in the mammal-defined PBR. We hypothesize that the tenth codon (residue 21) is an amphibian-specific PBR site that may be important in disease resistance. Trans-species and trans-generic polymorphisms are evident from exon-based genealogies, and co-phylogenetic analyses between intron, exon and mitochondrial based reconstructions reveal incongruent topologies, likely due to different locus histories. We developed two sets of barcoded adapters that reliably amplify a single and likely functional locus in all screened species using both 454 and Illumina based sequencing methods. These primers provide a resource for multiplexing and directly sequencing hundreds of samples in a single sequencing run, avoiding the labour and chimeric sequences associated with cloning, and enabling MHC population genetic analyses. Although the primers are currently limited to the 17 species we tested, these sequences and protocols provide a useful genetic resource and can serve as a starting point for future disease, adaptation and conservation studies across a range of anuran taxa.
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Affiliation(s)
- Kevin P Mulder
- Center for Conservation Genomics, Smithsonian Conservation Biology Institute, National Zoological Park, 3001 Connecticut Avenue NW, Washington, DC 20008, USA; CIBIO/InBIO, Research Centre in Biodiversity and Genetic Resources, Rua Padre Armando Quintas 7, Campus Agrário de Vairão, 4485-661 Vairão, Portugal
| | - Maria Cortazar-Chinarro
- Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, SE-75236, Uppsala, Sweden
| | - D James Harris
- CIBIO/InBIO, Research Centre in Biodiversity and Genetic Resources, Rua Padre Armando Quintas 7, Campus Agrário de Vairão, 4485-661 Vairão, Portugal
| | - Angelica Crottini
- CIBIO/InBIO, Research Centre in Biodiversity and Genetic Resources, Rua Padre Armando Quintas 7, Campus Agrário de Vairão, 4485-661 Vairão, Portugal
| | - Evan H Campbell Grant
- United States Geological Survey, Patuxent Wildlife Research Center, SO Conte Anadromous Fish Research Lab, 1 Migratory Way, Turner Falls, MA 01376, USA
| | - Robert C Fleischer
- Center for Conservation Genomics, Smithsonian Conservation Biology Institute, National Zoological Park, 3001 Connecticut Avenue NW, Washington, DC 20008, USA
| | - Anna E Savage
- Center for Conservation Genomics, Smithsonian Conservation Biology Institute, National Zoological Park, 3001 Connecticut Avenue NW, Washington, DC 20008, USA; Department of Biology, University of Central Florida, 4110 Libra Drive, Orlando, FL 32816, USA.
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121
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Chinchar V, Waltzek TB, Subramaniam K. Ranaviruses and other members of the family Iridoviridae: Their place in the virosphere. Virology 2017. [DOI: 10.1016/j.virol.2017.06.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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122
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Assis VR, Monteiro Titon SC, Teixeira Queiroz-Hazarbassanov NG, de Oliveira Massoco C, Ribeiro Gomes F. Corticosterone transdermal application in toads (Rhinella icterica): Effects on cellular and humoral immunity and steroid plasma levels. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2017; 327:200-213. [DOI: 10.1002/jez.2093] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 08/02/2017] [Accepted: 08/03/2017] [Indexed: 11/05/2022]
Affiliation(s)
- Vania Regina Assis
- Departamento de Fisiologia; Instituto de Biociências; Universidade de São Paulo; Rua do Matão; São Paulo Brazil
| | | | | | - Cristina de Oliveira Massoco
- Departamento de Patologia; Faculdade de Medicina Veterinária e Zootecnia; Universidade de São Paulo; São Paulo Brazil
| | - Fernando Ribeiro Gomes
- Departamento de Fisiologia; Instituto de Biociências; Universidade de São Paulo; Rua do Matão; São Paulo Brazil
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123
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Major histocompatibility complex variation and the evolution of resistance to amphibian chytridiomycosis. Immunogenetics 2017; 69:529-536. [PMID: 28695290 DOI: 10.1007/s00251-017-1008-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Accepted: 05/29/2017] [Indexed: 01/06/2023]
Abstract
Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), has been implicated in population declines and species extinctions of amphibians around the world. Susceptibility to the disease varies both within and among species, most likely attributable to heritable immunogenetic variation. Analyses of transcriptional expression in hosts following their infection by Bd reveal complex responses. Species resistant to Bd generally show evidence of stronger innate and adaptive immune system responses. Major histocompatibility complex (MHC) class I and class II genes of some susceptible species are up-regulated following host infection by Bd, but resistant species show no comparable changes in transcriptional expression. Bd-resistant species share similar pocket conformations within the MHC-II antigen-binding groove. Among susceptible species, survivors of epizootics bear alleles encoding these conformations. Individuals with homozygous resistance alleles appear to benefit by enhanced resistance, especially in environmental conditions that promote pathogen virulence. Subjects that are repeatedly infected and subsequently cleared of Bd can develop an acquired immune response to the pathogen. Strong directional selection for MHC alleles that encode resistance to Bd may deplete genetic variation necessary to respond to other pathogens. Resistance to chytridiomycosis incurs life-history costs that require further study.
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124
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Li WT, Chang HW, Pang VF, Wang FI, Liu CH, Chen TY, Guo JC, Wada T, Jeng CR. Mycolactone-producing Mycobacterium marinum infection in captive Hong Kong warty newts and pathological evidence of impaired host immune function. DISEASES OF AQUATIC ORGANISMS 2017; 123:239-249. [PMID: 28322210 DOI: 10.3354/dao03092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A mass mortality event of captive Hong Kong warty newts Paramesotriton hongkongensis with non-granulomatous necrotic lesions occurred in Taipei Zoo, Taiwan, in 2014. Clinically, the sick newts were lethargic and often covered with water mold Saprolegnia sp. on the skin of the body trunk or extremities. Predominant pathological findings were multifocal non-granulomatous necrotic lesions in the liver, spleen, and kidneys and severe skin infection with Saprolegnia sp., with deep invasion and involvement of underlying muscles. The possibility of ranavirus infection was ruled out by negative PCR results. Unexpectedly, abundant intralesional acid-fast positive bacilli were found in the necrotic lesions of the liver, spleen, and kidney in all 14 sick newts. PCR targeting the hsp65, ITS region, and partial 16S rRNA genes was performed, and the sequence identity from amplified amplicons of hsp65 and partial 16S rRNA genes was 100% identical to that of the corresponding gene fragment of Mycobacterium marinum. Further molecular investigations demonstrated that the current M. marinum was a mycolactone-producing mycobacterium with the presence of esxA/esxB genes. Mycolactone is a plasmid-encoded, immunosuppressive, and cytotoxic toxin. The possible immunosuppression phenomenon characterized by systemic non-granulomatous necrotic lesions caused by M. marinum and the unusual deep invasive infection caused by water mold might be associated with the immunosuppressive effect of mycolactone. Therefore, it should be noted that non-granulomatous necrotic lesions in amphibians can be caused not only by ranavirus infection but also by mycobacteriosis.
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Affiliation(s)
- Wen-Ta Li
- Graduate Institute of Molecular and Comparative Pathobiology, School of Veterinary Medicine, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd, Taipei 10617, Taiwan
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Balàž V, Gortázar Schmidt C, Murray K, Carnesecchi E, Garcia A, Gervelmeyer A, Martino L, Munoz Guajardo I, Verdonck F, Zancanaro G, Fabris C. Scientific and technical assistance concerning the survival, establishment and spread of Batrachochytrium salamandrivorans (Bsal) in the EU. EFSA J 2017; 15:e04739. [PMID: 32625419 PMCID: PMC7010177 DOI: 10.2903/j.efsa.2017.4739] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A new fungus, Batrachochytrium salamandrivorans (Bsal), was identified in wild populations of salamanders in the Netherlands and Belgium, and in kept salamander populations in Germany and the United Kingdom. EFSA assessed the potential of Bsal to affect the health of wild and kept salamanders in the EU, the effectiveness and feasibility of a movement ban of traded salamanders, the validity, reliability and robustness of available diagnostic methods for Bsal detection, and possible alternative methods and feasible risk mitigation measures to ensure safe international and EU trade of salamanders and their products. Bsal was isolated and characterised in 2013 from a declining fire salamander (Salamandra salamandra) population in the Netherlands. Based on the available evidence, it is likely that Bsal is a sufficient cause for the death of S. salamandra both in the laboratory and in the wild. Despite small sample sizes, the available experimental evidence indicates that Bsal is associated with disease and death in individuals of 12 European and 3 Asian salamander species, and with high mortality rate outbreaks in kept salamanders. Bsal experimental infection was detected in individuals of at least one species pertaining to the families Salamandridae, Plethodontidae, Hynobiidae and Sirenidae. Movement bans constitute key risk mitigation measures to prevent pathogen spread into naïve areas and populations. The effectiveness of a movement ban is mainly dependent on the import volumes, possibility of Bsal to remain viable outside susceptible/tolerant species, and the capacity to limit illegal movements. Duplex real-time PCR can be used to detect Bsal DNA, but has not been fully validated. Quarantining salamanders, enacting legislation that requires testing of animals to demonstrate freedom from Bsal, before movement can take place, restricting salamander movements, tracking all traded species, hygienic procedures/biosecurity measures before and during movements, and increasing public awareness are relevant measures for ensuring safe intra-EU and international trade of salamanders.
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