451
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Blaustein AR, Romansic JM, Kiesecker JM, Hatch AC. Ultraviolet radiation, toxic chemicals and amphibian population declines. DIVERS DISTRIB 2003. [DOI: 10.1046/j.1472-4642.2003.00015.x] [Citation(s) in RCA: 256] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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452
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453
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Davidson EW, Jancovich JK, Borland S, Newberry M, Gresens J. Diagnosis: Ranavirus Infection. Lab Anim (NY) 2003. [DOI: 10.1038/laban0303-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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454
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455
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Swine Flu or 1918 Pandemic? Upper Respiratory Tract Disease and the Sudden Mortality of Gopher Tortoises (Gopherus polyphemus) on a Protected Habitat in Florida. J HERPETOL 2003. [DOI: 10.1670/0022-1511(2003)037[0137:sfopur]2.0.co;2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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456
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457
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Rollins-Smith LA, Carey C, Conlon JM, Reinert LK, Doersam JK, Bergman T, Silberring J, Lankinen H, Wade D. Activities of temporin family peptides against the chytrid fungus (Batrachochytrium dendrobatidis) associated with global amphibian declines. Antimicrob Agents Chemother 2003; 47:1157-60. [PMID: 12604562 PMCID: PMC149293 DOI: 10.1128/aac.47.3.1157-1160.2003] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2002] [Revised: 10/21/2002] [Accepted: 12/16/2002] [Indexed: 11/20/2022] Open
Abstract
Temporin A and structurally related peptides produced in amphibian dermal granular glands and in wasp venom were tested for growth inhibition of Batrachochytrium dendrobatidis, a pathogen associated with global amphibian declines. Two natural amphibian temporins, a wasp temporin, and six synthetic analogs effectively inhibited growth. Differences in potency due to amino acid substitution suggest that ability to penetrate membranes and form an alpha-helical structure is important for their effectiveness against this pathogen.
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Affiliation(s)
- Louise A Rollins-Smith
- Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
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458
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459
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Kouba AJ, Vance CK, Frommeyer MA, Roth TL. Structural and functional aspects of Bufo americanus spermatozoa: effects of inactivation and reactivation. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, COMPARATIVE EXPERIMENTAL BIOLOGY 2003; 295:172-82. [PMID: 12541301 DOI: 10.1002/jez.a.10192] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Very little is known about the effects of manipulating toad sperm activity in vitro, and such information is important in the development of a genetic resource bank for bufonid species. The specific objectives of this study were to: 1). identify the optimal inactivation and reactivation solutions for toad spermatozoa collected in urine; 2). establish the length of time toad spermatozoa can be exposed to an inactivation buffer and still resume motility upon reactivation; 3). evaluate the consequence of inactivation on specific sperm characteristics; and 4). characterize the sperm mitochondria vesicle (MV) and its relationship to motility. Reactivated sperm motility was similar after inactivation in either Simplified Amphibian Ringers (SAR) solution or DeBoer's (DB) solution. Diluting the buffer by 80% with water provided the best method for reactivating sperm. Dilutions with NaCl solutions (10-50 mM) produced inferior results. SAR-inactivated spermatozoa could remain suspended up to 4 hr and still regain 25% of initial motility upon reactivation in water. Compared to the controls, sperm motility was greater (P<0.01) over time for samples treated with SAR, although forward progression was significantly lower. Furthermore, SAR treatment resulted in sperm samples with a greater number of viable, morphologically normal, and intact MVs over time. Electron microscopy and fluorescent staining confirmed that the toad sperm's MV contains a large number of active mitochondria with very few other cytoplasmic structures. Nearly all spermatozoa exhibiting motility had an intact MV, and dissociation of this structure was clearly related to motility loss. In conclusion, toad spermatozoa can be effectively inactivated and reactivated by varying the osmolality of the external solutions and, although sperm forward progression is reduced, all other characteristics are well maintained. Moreover, the increased number of spermatozoa with intact MV after inactivation suggests the process may help preserve this important structure.
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Affiliation(s)
- Andrew J Kouba
- Center for Conservation and Research of Endangered Wildlife, Cincinnati Zoo and Botanical Garden, Cincinnati, Ohio 45220, USA.
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460
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Morehouse EA, James TY, Ganley ARD, Vilgalys R, Berger L, Murphy PJ, Longcore JE. Multilocus sequence typing suggests the chytrid pathogen of amphibians is a recently emerged clone. Mol Ecol 2003; 12:395-403. [PMID: 12535090 DOI: 10.1046/j.1365-294x.2003.01732.x] [Citation(s) in RCA: 173] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Chytridiomycosis is a recently identified fungal disease associated with global population declines of frogs. Although the fungus, Batrachochytrium dendrobatidis, is considered an emerging pathogen, little is known about its population genetics, including the origin of the current epidemic and how this relates to the dispersal ability of the fungus. In this study, we use multilocus sequence typing to examine genetic diversity and relationships among 35 fungal strains from North America, Africa and Australia. Only five variable nucleotide positions were detected among 10 loci (5918 bp). This low level of genetic variation is consistent with the description of B. dendrobatidis as a recently emerged disease agent. Fixed (i.e. 100%) or nearly fixed frequencies of heterozygous genotypes at two loci suggested that B. dendrobatidis is diploid and primarily reproduces clonally. In contrast to the lack of nucleotide polymorphism, electrophoretic karyotyping of multiple strains demonstrated a number of chromosome length polymorphisms.
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Affiliation(s)
- Erica A Morehouse
- Department of Biology, Biological Sciences Building, Room 139, Duke University, Durham, NC 27708, USA
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461
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Green DE, Converse KA, Schrader AK. Epizootiology of sixty-four amphibian morbidity and mortality events in the USA, 1996-2001. Ann N Y Acad Sci 2002; 969:323-39. [PMID: 12381613 DOI: 10.1111/j.1749-6632.2002.tb04400.x] [Citation(s) in RCA: 240] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
A total of 44 amphibian mortality events and 20 morbidity events were reviewed retrospectively. The most common cause of amphibian mortality events was infection by ranaviruses (Family: Iridoviridae). Ranavirus epizootics have abrupt onset and affect late-stage larvae and recent metamorphs. Mortality events due to ranavirus infections affected only widespread and abundant amphibian species, and there was a clear association with high population densities. Chytrid fungal infections accounted for seven mortality events in postmetamorphic anurans only. Chytrid epizootics are insidious and easily overlooked in the field. While both ranavirus and chytrid fungal epizootics were associated with > 90% mortality rates at affected sites, only the chytrid fungal infections were linked to multiple amphibian population declines. Three primitive fungal organisms in the newly erected clade, Mesomycetozoa, caused morbidities and mortalities in anurans and salamanders.
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Affiliation(s)
- D Earl Green
- United States Geological Survey, National Wildlife Health Center, Madison, Wisconsin 53711 USA
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462
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Rollins-Smith LA, Reinert LK, Miera V, Conlon JM. Antimicrobial peptide defenses of the Tarahumara frog, Rana tarahumarae. Biochem Biophys Res Commun 2002; 297:361-7. [PMID: 12237127 DOI: 10.1016/s0006-291x(02)02217-9] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Populations of the Tarahumara frog Rana tarahumarae have decreased markedly in recent years in the northern part of their range. Infection by the chytrid fungus Batrachochytrium dendrobatidis has been implicated in these declines. To determine whether antimicrobial peptides in the skin provide protection against this pathogen, norepinephrine-stimulated skin secretions were tested for their ability to inhibit growth of B. dendrobatidis in vitro. After concentration, crude mixtures of skin peptides inhibited the growth of the chytrid in a concentration-dependent manner. Proteomic analysis led to the identification and characterization of three peptides belonging to the brevinin-1 family of antimicrobial peptides and three belonging to the ranatuerin-2 family. The two most abundant peptides, ranatuerin-2TRa (GIMDSIKGAAKEIAGHLLDNLKCKITGC) and brevinin-1TRa (FLPVIAGIAANVLPKLFCKLTKRC), were active against B. dendrobatidis (MIC of 50 microM for ranatuerin-2TRa and 12.5 microM for brevinin-1TRa against zoospores). These data clearly show that antimicrobial peptides in the skin secretions of the Tarahumara frog are active against B. dendrobatidis and should provide some protection against infection. Therefore, the observed susceptibility of these frogs to this pathogen in the wild may be due to the effects of additional environmental factors that impair this innate defense mechanism, leading to the observed population declines.
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Affiliation(s)
- Louise A Rollins-Smith
- Department of Microbiology, A-5301 Medical Center North, Vanderbilt University, Nashville, TN 37232, USA.
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463
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464
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Blaustein AR, Kiesecker JM. Complexity in conservation: lessons from the global decline of amphibian populations. Ecol Lett 2002. [DOI: 10.1046/j.1461-0248.2002.00352.x] [Citation(s) in RCA: 377] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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465
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466
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Harvell CD, Mitchell CE, Ward JR, Altizer S, Dobson AP, Ostfeld RS, Samuel MD. Climate warming and disease risks for terrestrial and marine biota. Science 2002; 296:2158-62. [PMID: 12077394 DOI: 10.1126/science.1063699] [Citation(s) in RCA: 1154] [Impact Index Per Article: 52.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Infectious diseases can cause rapid population declines or species extinctions. Many pathogens of terrestrial and marine taxa are sensitive to temperature, rainfall, and humidity, creating synergisms that could affect biodiversity. Climate warming can increase pathogen development and survival rates, disease transmission, and host susceptibility. Although most host-parasite systems are predicted to experience more frequent or severe disease impacts with warming, a subset of pathogens might decline with warming, releasing hosts from disease. Recently, changes in El Niño-Southern Oscillation events have had a detectable influence on marine and terrestrial pathogens, including coral diseases, oyster pathogens, crop pathogens, Rift Valley fever, and human cholera. To improve our ability to predict epidemics in wild populations, it will be necessary to separate the independent and interactive effects of multiple climate drivers on disease impact.
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Affiliation(s)
- C Drew Harvell
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA.
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467
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Rollins-Smith LA, Carey C, Longcore J, Doersam JK, Boutte A, Bruzgal JE, Conlon JM. Activity of antimicrobial skin peptides from ranid frogs against Batrachochytrium dendrobatidis, the chytrid fungus associated with global amphibian declines. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2002; 26:471-479. [PMID: 11906726 DOI: 10.1016/s0145-305x(01)00088-x] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Accumulating evidence suggests that a chytrid fungus, Batrachochytrium dendrobatidis, is responsible for recent declines in amphibian populations in Australia, Central America, Europe, and North America. Because the chytrid infects the keratinized epithelium of the skin, we investigated the possible role of antimicrobial peptides produced in the skin as inhibitors of infection and growth. We show here that 10 peptides representing eight families of peptides derived from North American ranid frogs can effectively inhibit growth of this chytrid. The peptides are members of the ranatuerin-1, ranatuerin-2, esculentin-1, esculentin-2, brevinin-2, temporin, palustrin-3, and ranalexin families. All the tested peptides inhibit growth of mature fungal cells at concentrations above 25 microM, and some of them inhibit at concentrations as low as 2 microM. A comparison of the sensitivity of infectious zoospores with that of mature cells showed that the zoospores are inhibited at significantly lower concentrations of peptides. To determine whether cold temperature interferes with the inhibitory effects of these peptides, we tested their effectiveness at both 22 and 10 degrees C. Although the peptides inhibit at both temperatures, they appear to be more effective against zoospores at the lower temperature. These results suggest that the ranid frogs have, within their repertoire of antimicrobial substances, a number of skin peptides that should be a deterrent to chytrid infection. This may provide some natural resistance to infection, but if environmental factors inhibit the synthesis and release of the skin peptides, the pathogen could gain the advantage.
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Affiliation(s)
- Louise A Rollins-Smith
- Departments of Microbiology and Immunology & Pediatrics, Vanderbilt University, Medical Center North, A-5301, Nashville, TN 37232, USA.
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468
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Abstract
The epizootic hematopoietic necrosis virus (EHNV) is a strain of the Iridovirus genus, which includes viruses seriously affecting native and aquacultured fish and amphibians. Despite its growing importance as a threat to fish farming, very little information is available on the biochemical and immunological nature of this virus. To identify and characterize the main antigenic determinants of EHNV, a panel of murine monoclonal antibodies was produced upon parenteral inoculation with live virus. A total of 124 primary hybridoma cultures from two fusions was found to produce antibodies reacting with EHNV by ELISA, but no neutralizing monoclonal antibody was detected. Twenty hybridoma cultures were randomly chosen for further study, and the antibodies secreted were analyzed by Western blotting, radioimmunoprecipitation, and immunostaining of infected cells. Only three MAbs immunoprecipitated the 50-kDa EHNV major capsid protein (MCP) from infected cell lysates, but they did not stain this protein in Western blotting. Eight and five further MAbs recognized peptides of approximately 15 and 18 kDa, respectively. Four antibodies could not be mapped into any viral protein, although they specifically immunostained virus-infected cells and reacted with purified EHNV virions by ELISA. These latter MAbs and the three antibodies directed at the MCP are likely to recognize conformation-dependent epitopes on the virus capsid proteins.
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Affiliation(s)
- Marina Monini
- Laboratorio di Ultrastrutture, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
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469
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Rollins-Smith LA. Neuroendocrine-immune system interactions in amphibians: implications for understanding global amphibian declines. Immunol Res 2002; 23:273-80. [PMID: 11444392 DOI: 10.1385/ir:23:2-3:273] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Amphibians are ancient creatures valued by biologists and naturalists around the world. They share with all other vertebrates a complex neuroendocrine system that enables them to flourish in a variety of aquatic and semiaquatic environments. Studies from a number of laboratories have demonstrated that the immune system of amphibian species is nearly as complex as that of mammals. Yet for reasons that are not well understood, amphibian species are facing greater survival challenges than in the recent past. This article will review our current understanding of the neuroendocrine immune system interactions in amphibians and address the question of whether environmental stressors may contribute to immunosuppression and amphibian declines.
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Affiliation(s)
- L A Rollins-Smith
- Department of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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470
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Rollins-Smith LA, Doersam JK, Longcore JE, Taylor SK, Shamblin JC, Carey C, Zasloff MA. Antimicrobial peptide defenses against pathogens associated with global amphibian declines. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2002; 26:63-72. [PMID: 11687264 DOI: 10.1016/s0145-305x(01)00041-6] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Global declines of amphibian populations are a source of great concern. Several pathogens that can infect the skin have been implicated in the declines. The pathogen most frequently associated with recent die-offs is a chytrid fungus, Batrachochytrium dendrobatidis. A second fungus, Basidiobolus ranarum, was isolated from declining populations of Wyoming toads. A third pathogen, Aeromonas hydrophila, is an opportunistic bacterium found in healthy frogs, but capable of inducing disease. Among the immune defense mechanisms used by amphibians is the production of antimicrobial peptides in granular glands in the skin. These packets of natural antibiotics can be emptied onto the skin when the amphibian is injured. To determine whether antimicrobial skin peptides defend against these amphibian pathogens, six peptides (magainin I, magainin II, PGLa, CPF, ranalexin, and dermaseptin), from three species, and representing three structurally different families of peptides, were tested in growth inhibition assays. We show here that the peptides can kill or inhibit growth of both fungi but not Aeromonas. Although each peptide varied in its effectiveness, at least one from each species was effective against both fungi at a concentration of about 10-20 microM. This is the first direct evidence that antimicrobial peptides in the skin can operate as a first line of defense against the organisms associated with global amphibian declines. It suggests that this innate defense mechanism may play a role in preventing or limiting infection by these organisms.
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Affiliation(s)
- Louise A Rollins-Smith
- Departments of Microbiology and Immunology and of Pediatrics, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
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471
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Just F, Essbauer S, Ahne W, Blahak S. Occurrence of an invertebrate iridescent-like virus (Iridoviridae) in reptiles. JOURNAL OF VETERINARY MEDICINE. B, INFECTIOUS DISEASES AND VETERINARY PUBLIC HEALTH 2001; 48:685-94. [PMID: 11765804 DOI: 10.1046/j.1439-0450.2001.00495.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Viral isolates were obtained in 1998, 1999 and 2000 from the lung, liver and intestine of two bearded dragons (Pogona vitticeps) and a chameleon (Chamaeleo quadricornis) and from the skin of a frill-necked lizard (Chamydosaurus kingii) by using viper heart cells (VH2) at 28 degrees C. Electron microscopic examination of infected VH2 cells revealed the assembly of icosahedral iridovirus-like particles measuring 139 nm (side to side) and 151 nm (apex to apex). Negatively stained virus particles had dimensions of 149 nm (side to side) and 170 nm (apex to apex). Polymerase chain reaction (PCR) amplification of purified viral DNA with primers corresponding to the partial gene encoding the major capsid protein (MCP) of Frog viris-3 (FV-3), the type species of the genus Ranavirus, was unsuccessful. In contrast, primers corresponding to the partial MCP gene of Chilo iridescent virus (CIV; genus Iridovirus) amplified 500-bp products with 97% identity to the nucleotide sequence of CIV and 100% identity to the nucleotide sequence of Gryllus bimaculatus iridescent virus (GbIV), an invertebrate iridescent virus. Virus protein profiles analysed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and restriction fragment length profiles of purified viral DNA treated with the endonucleases EcoRI, HindIII and HpaII were identical to those of GbIV.
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Affiliation(s)
- F Just
- Institute of Zoology, Fishery Biology and Fish Diseases, Faculty of Veterinary Medicine, Ludwig-Maximilian's University Munich, Gemany
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472
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Chinchar VG, Wang J, Murti G, Carey C, Rollins-Smith L. Inactivation of frog virus 3 and channel catfish virus by esculentin-2P and ranatuerin-2P, two antimicrobial peptides isolated from frog skin. Virology 2001; 288:351-7. [PMID: 11601906 DOI: 10.1006/viro.2001.1080] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
While it is clear that some amphibian populations have recently experienced precipitous declines, the causes of those die-offs are complex and likely involve multiple variables. One theory suggests that environmental factors may trigger events that result in depressed immune function and increased susceptibility to infectious disease. Here we examine one aspect of innate immunity in amphibians and show that esculentin-2P (E2P) and ranatuerin-2P (R2P), two antimicrobial peptides isolated from Rana pipiens, inactivate frog virus 3, a potentially pathogenic iridovirus infecting anurans, and channel catfish herpesvirus. In contrast to mammalian antimicrobial peptides, E2P and R2P act within minutes, at temperatures as low as 0 degrees C, to inhibit viral infectivity. Moreover, these compounds appear to inactivate the virus directly and do not act by inhibiting replication in infected cells. This is the first report linking amphibian antimicrobial peptides with protection from an amphibian viral pathogen and suggests that these compounds may play a role in maintaining amphibian health.
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Affiliation(s)
- V G Chinchar
- Department of Microbiology, University of Mississippi Medical Center, Jackson, Mississippi 39216, USA.
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473
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Essbauer S, Ahne W. Viruses of lower vertebrates. JOURNAL OF VETERINARY MEDICINE. B, INFECTIOUS DISEASES AND VETERINARY PUBLIC HEALTH 2001; 48:403-75. [PMID: 11550762 PMCID: PMC7159363 DOI: 10.1046/j.1439-0450.2001.00473.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Viruses of lower vertebrates recently became a field of interest to the public due to increasing epizootics and economic losses of poikilothermic animals. These were reported worldwide from both wildlife and collections of aquatic poikilothermic animals. Several RNA and DNA viruses infecting fish, amphibians and reptiles have been studied intensively during the last 20 years. Many of these viruses induce diseases resulting in important economic losses of lower vertebrates, especially in fish aquaculture. In addition, some of the DNA viruses seem to be emerging pathogens involved in the worldwide decline in wildlife. Irido-, herpes- and polyomavirus infections may be involved in the reduction in the numbers of endangered amphibian and reptile species. In this context the knowledge of several important RNA viruses such as orthomyxo-, paramyxo-, rhabdo-, retro-, corona-, calici-, toga-, picorna-, noda-, reo- and birnaviruses, and DNA viruses such as parvo-, irido-, herpes-, adeno-, polyoma- and poxviruses, is described in this review.
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Affiliation(s)
- S Essbauer
- WHO Centre for Comparative Virology, Institute of Medical Microbiology, Infectious and Epidemic Diseases, Ludwig-Maximilians-Universität, Munich, Germany.
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474
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Abstract
The first part of this paper surveys emerging pathogens of wildlife recorded on the ProMED Web site for a 2-year period between 1998 and 2000. The majority of pathogens recorded as causing disease outbreaks in wildlife were viral in origin. Anthropogenic activities caused the outbreaks in a significant majority of cases. The second part of the paper develops some matrix models for quantifying the basic reproductive number, R(0), for a variety of potential types of emergent pathogen that cause outbreaks in wildlife. These analyses emphasize the sensitivity of R(0) to heterogeneities created by either the spatial structure of the host population, or the ability of the pathogens to utilize multiple host species. At each stage we illustrate how the approach provides insight into the initial dynamics of emergent pathogens such as canine parvovirus, Lyme disease, and West Nile virus in the United States.
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Affiliation(s)
- A Dobson
- Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08544-1003, USA.
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475
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Rowson AD, Obringer AR, Roth TL. Non-invasive treatments of luteinizing hormone-releasing hormone for inducing spermiation in American (Bufo americanus) and Gulf Coast (Bufo valliceps) toads. Zoo Biol 2001; 20:63-74. [PMID: 11429778 DOI: 10.1002/zoo.1007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
As many as 20% of all assessed amphibian species are threatened with extinction, and captive breeding programs are becoming important components of conservation strategies for this taxon. For some species, exogenous hormone administration has been integrated into breeding protocols to improve propagation. However, most treatments are administered by an intraperitoneal injection that can be associated with some risks. The general goal of this study was to identify a non-invasive method of applying luteinizing hormone-releasing hormone (LHRH), which reliably induces sperm release in toads. Specific objectives were to 1) test the spermiation response after topical application of different LHRH doses to the abdominal seat region, 2) evaluate the effects of adding the absorption enhancers dimethyl sulfoxide (DMSO), acetone, and glyceryl monocaprylate (GMC) to the LHRH, 3) assess the spermiation response after oral delivery of LHRH in a mealworm vehicle, and 4) compare sperm characteristics and spermiation responses to treatments in two different toad species. Male American (n = 9) and Gulf Coast (n = 7) toads were rotated systematically through a series of treatments. Urine was collected and evaluated for the presence of sperm at 0, 3, 7, 12, and 24 hours post-treatment. There were no statistical differences in spermiation induction or sperm characteristics between American and Gulf Coast toads after the treatments. Oral administration of 100 &mgr;g LHRH was occasionally successful in inducing spermiation, but results appeared largely unreliable. Ventral dermal application of 100 or 10 &mgr;g LHRH in 40% DMSO were more effective (P < 0.05) at inducing spermiation compared with the other treatments tested, eliciting sperm release in more than 70% of toads tested. In breeding programs for rare and/or fragile anurans, these non-invasive methods of exogenous hormone administration might be preferred over intraperitoneal injections. Zoo Biol 20:63-74, 2001. Copyright 2001 Wiley-Liss, Inc.
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Affiliation(s)
- Angela D. Rowson
- Center for Research of Endangered Wildlife, Cincinnati Zoo and Botanical Garden, Cincinnati, Ohio
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476
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Raverty S, Reynolds T. Cutaneous chytridiomycosis in dwarf aquatic frogs (Hymenochirus boettgeri) originating from southeast Asia and in a western toad (Bufo boreas) from northeastern British Columbia. THE CANADIAN VETERINARY JOURNAL = LA REVUE VETERINAIRE CANADIENNE 2001; 42:385-6. [PMID: 11360864 PMCID: PMC1476510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Affiliation(s)
- S Raverty
- Animal Health Centre, British Columbia Ministry of Agriculture and Food, 1767 Angus Campbell Road, Abbotsford, British Columbia V3G 2M3
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477
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Daszak P, Cunningham AA, Hyatt AD. Anthropogenic environmental change and the emergence of infectious diseases in wildlife. Acta Trop 2001; 78:103-16. [PMID: 11230820 DOI: 10.1016/s0001-706x(00)00179-0] [Citation(s) in RCA: 500] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
By using the criteria that define emerging infectious diseases (EIDs) of humans, we can identify a similar group of EIDs in wildlife. In the current review we highlight an important series of wildlife EIDs: amphibian chytridiomycosis; diseases of marine invertebrates and vertebrates and two recently-emerged viral zoonoses, Nipah virus disease and West Nile virus disease. These exemplify the varied etiology, pathogenesis, zoonotic potential and ecological impact of wildlife EIDs. Strikingly similar underlying factors drive disease emergence in both human and wildlife populations. These are predominantly ecological and almost entirely the product of human environmental change. The implications of wildlife EIDs are twofold: emerging wildlife diseases cause direct and indirect loss of biodiversity and add to the threat of zoonotic disease emergence. Since human environmental changes are largely responsible for their emergence, the threats wildlife EIDs pose to biodiversity and human health represent yet another consequence of anthropogenic influence on ecosystems. We identify key areas where existing expertise in ecology, conservation biology, wildlife biology, veterinary medicine and the impact of environmental change would augment programs to investigate emerging diseases of humans, and we comment on the need for greater medical and microbiological input into the study of wildlife diseases.
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Affiliation(s)
- P Daszak
- Institute of Ecology, University of Georgia, Athens GA 30602, USA.
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Abstract
Changes in the epidemiology of infectious diseases are the direct result of ecological and evolutionary changes in hosts and parasites. Precisely what the causal processes are is rarely known in any particular case, and this hinders the design of appropriate control strategies. This is particularly so for emerging infections, as opportunity is rapidly lost to study the ecological parameters which might have affected initial emergence. However, molecular evolutionary studies of the pathogens can yield data which discriminate between possible causes. The current distribution of DNA sequence variation is important information which may reveal past and current changes in pathogen population structures, and can also identify adaptive changes in pathogen genes which have affected their evolution. Such studies have been quite intensively performed on particular viral and bacterial pathogens, and some of the successes of these are noted here. Approaches to understanding the recent evolution of eukaryotic pathogens are outlined, with particular reference to current problems of emerging zoonoses, and changes in virulence and drug resistance.
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Affiliation(s)
- D J Conway
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London, UK.
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Daszak P, Cunningham AA. More on the ecological impact of fungal infections on wildlife populations. PARASITOLOGY TODAY (PERSONAL ED.) 2000; 16:404-5. [PMID: 10951603 DOI: 10.1016/s0169-4758(00)01714-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Daszak P, Cunningham AA, Hyatt AD. Emerging infectious diseases of wildlife--threats to biodiversity and human health. Science 2000; 287:443-9. [PMID: 10642539 DOI: 10.1126/science.287.5452.443] [Citation(s) in RCA: 2301] [Impact Index Per Article: 95.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Emerging infectious diseases (EIDs) of free-living wild animals can be classified into three major groups on the basis of key epizootiological criteria: (i) EIDs associated with "spill-over" from domestic animals to wildlife populations living in proximity; (ii) EIDs related directly to human intervention, via host or parasite translocations; and (iii) EIDs with no overt human or domestic animal involvement. These phenomena have two major biological implications: first, many wildlife species are reservoirs of pathogens that threaten domestic animal and human health; second, wildlife EIDs pose a substantial threat to the conservation of global biodiversity.
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Affiliation(s)
- P Daszak
- Institute of Ecology, University of Georgia, Athens, GA 30602, USA.
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