identification and characterization of the frog virus 3 dna methyltransferase gene.cytosine dna methyltransferases (mtases) first recognize specific nucleotide sequences and then transfer a methyl group from s-adenosylmethionine to cytosine. this division of function is reflected in five highly conserved motifs shared by cytosine mtases. the region containing the first four motifs is responsible for the catalytic function whereas the region containing the fifth motif v provides specificity of binding to dna. in at least one case, two separate proteins, one containing the first ...19957636474
a fully 5'-cg-3' but not a 5'-ccgg-3' methylated late frog virus 3 promoter retains activity.several lines of evidence demonstrate that the dna of the iridovirus frog virus 3 (fv3) is methylated in all 5'-cg-3' sequences both in virion dna and in the intracellular viral dna at late times after infection. the 5-methyldeoxycytidine residues in this viral dna occur exclusively in 5'-cg-3' dinucleotide positions. we have cloned and determined the nucleotide sequence of the l1140 gene and its promoter from fv3 dna. the gene encodes a 40-kda protein. the results of transcriptional pattern ana ...19957884871
transactivation of methylated hiv-ltr by a frog virus 3 protein.dna methylation has been implicated in the suppression of transcription of a large spectrum of eukaryotic genes. frog virus 3 (fv3) contains genomic dna that is the most extensively methylated of all known animal viruses. however, fv3 gene expression is tightly regulated in a sequential fashion in infected cells. therefore, fv3 must have evolved a mechanism(s) to overcome the inhibitory effects of dna methylation. fv3 has been shown to induce expression of methylated foreign genes in transient t ...19947941333
a preliminary translational map of the frog virus 3 genome.a preliminary map of the frog virus 3 (fv 3) genome was constructed by hybridization-selection of mrnas to cloned dna fragments and translation in reticulocyte lysates. fv 3 mrnas were hybridized to kpni, hindiii, and sali restriction fragments representing the entire fv 3 genome. two different hybridization conditions were employed in order to discriminate between the hybridization of early and late mrnas. a total of 43 major and 18 minor early genes and nine major and three minor late genes we ...19948209422
patterns of frog virus 3 dna methylation and dna methyltransferase activity in nuclei of infected cells.the iridovirus frog virus 3 (fv3) can replicate in culture in fat head minnow (fhm) fish cells or in bhk-21 hamster cells. viral dna replication commences about 3 h after infection of fhm cells with fv3. between 3 and 6 h postinfection (p.i.), a portion of the intranuclear fv3 dna is partly unmethylated. at later times, p.i., all of the viral dna in the nuclear and cytoplasmic compartments is methylated at the 5'-ccgg-3' sequences. cytoplasmic fv3 dna has not been found unmethylated. we have clo ...19938230420
spread of epizootic haematopoietic necrosis virus (ehnv) in redfin perch (perca fluviatilis) in southern australia. 19968660213
development of dna diagnostic methods for the detection of new fish iridoviral diseases.a new disease of epidemic proportions caused by fish viruses within the iridoviridae family inflicts serious damage on red sea breams (pagrus major) and striped jack (caranx delicatissimus) populations grown in aquacultures in japan. a partial segment of the fish iridoviral dna was directly amplified using the polymerase chain reaction (pcr) with synthetic primers designed from well conserved nucleotide sequences between the frog virus 3 (ranavirus) and the silkworm iridescent virus type 6. the ...19979094219
detection of antibodies against iridoviruses in the serum of the amphibian bufo marinus.sera from the amphibian bufo marinus (cane or marine toad) were investigated using a newly-developed enzyme-linked immunosorbent assay for the detection of antibodies to ranaviruses (family iridoviridae). epizootic haematopoietic necrosis virus (ehnv) or bohle iridovirus (biv) was affinity purified from cell culture supernatants and simultaneously bound to the solid phase using specific linker antibodies. after binding to antigen, antibodies in bufo marinus serum were then detected with a specif ...19979395145
isolation and characterization of iridoviruses from the giant toad bufo marinus in this communication we describe for the first time the isolation of 7 iridoviruses from the toad bufo marinus and an unknown species of frog leptodactylus in venezuela, south america. the viruses are icosahedral with electron-dense cores, each of which is surrounded by an inner membrane, capsid and a cell-derived envelope. the virus(es) have an average vertex to vertex diameter of 160 nm and replicate in the cytoplasm of a range of cell lines. within the cytoplasm of infected cells, rarefied a ...19989653454
comparison of european systemic piscine and amphibian iridoviruses with epizootic haematopoietic necrosis virus and frog virus 3.iridovirus-like agents isolated from systemic infected fish (silurus glanis, sfir; ictalurus melas, cfir i, cfir ii, cfir iii) and from frogs (rana esculenta, reir) in europe, epizootic haematopoietic necrosis virus (ehnv) isolated in australia from redfin perch (perca fluviatilis), and frog virus 3 (fv 3) isolated from frogs (rana pipiens) in the usa were investigated by electron microscopy, polypeptide composition, immunofluorescence, restriction endonuclease digestion, southern-blot hybridiza ...19989719770
an improved enzyme linked immunosorbent assay for detection of anti-ranavirus antibodies in the serum of the giant toad (bufo marinus).an improved ranavirus antibody elisa (r ab elisa) for the specific detection of anti-ranavirus antibodies in toad sera was developed. sheep anti-epizootic haematopoietic necrosis virus (ehnv) was used as the antigen-capture antibody. ehnv was used as the antigen and sera from field and challenged toads were used to detect the virus. rabbit anti-toad igg and igm were used to detect bound toad antibody. pre-absorption of toad sera with a monoclonal antibody, raised against the 50 kda ehnv protein, ...19989877438
pathology, isolation, and preliminary molecular characterization of a novel iridovirus from tiger salamanders in saskatchewan.all iridovirus was confirmed to be the cause of an epizootic in larval and adult tiger salamanders (ambystoma tigrinum diaboli) from four separate ponds in southern saskatchewan (canada) during the summer of 1997. this organism also is suspected, based on electron microscopic findings, to be the cause of mortality of larval tiger salamanders in a pond over 200 km to the north during the same year. salamanders developed a generalized viremia which resulted in various lesions including: necrotizin ...199910479075
isolation and characterization of an iridovirus from hermann's tortoises (testudo hermanni).a virus was isolated from tissues of 2 diseased hermann's tortoises (testudo hermanni) and preliminarily characterized as an iridovirus. this conclusion was based on the presence of inclusion bodies in the cytoplasm of infected cells, sensitivity to chloroform, inhibition of virus replication by 5-iodo-2'-desoxyuridine and the size and icosahedral morphology of viral particles. the virus was able to replicate in several reptilian, avian and mammalian cell lines at 28 degrees c, but not at 37 deg ...199910550665
emerging infectious diseases and amphibian population declines.we review recent research on the pathology, ecology, and biogeography of two emerging infectious wildlife diseases, chytridiomycosis and ranaviral disease, in the context of host-parasite population biology. we examine the role of these diseases in the global decline of amphibian populations and propose hypotheses for the origins and impact of these panzootics. finally, we discuss emerging infectious diseases as a global threat to wildlife populations.199910603206
preliminary description of lesions in juvenile largemouth bass injected with largemouth bass virus.juvenile largemouth bass micropterus salmoides were intraperitoneally injected with largemouth bass virus (lmbv), a member of the genus ranavirus, family iridoviridae. moribund fish which had been injected with 10(6.2) tissue culture infectious doses, 50% endpoint (tcid50), were sampled 4 d after injection; other largemouth bass injected with this dose died between 3 and 5 d after injection. fish injected with 10(2.8) tcid50 of lmbv were also examined after 4 d and had lesions similar to those o ...200010715819
recovery of ranavirus dsdna from formalin-fixed archival material.the extraction and amplification of nucleic acid from formalin-fixed and paraffin-embedded tissues has become an important exercise in the collection of retrospective epidemiological data. a protocol is described that enables the extraction and amplification of dsdna from fixed tissues within paraffin blocks and from specimens stored in 10% (aq) formalin. the procedure can be used for the examination of ranavirus dna within archival tissues thereby providing valuable data for identifying the ori ...200010715821
comparative studies of piscine and amphibian iridoviruses.a total of 30 iridoviruses collected from australia, south-east asia, north america, south america and europe were characterised. with the exception of the south-east asian iridoviruses all viruses were found to belong to the genus ranavirus. all viruses, except those originating from south-east asia, cross-reacted with antisera against epizootic haematopoietic necrosis virus (ehnv). viruses or virus-infected cells were examined using electron microscopy, sds page, restriction endonuclease (re) ...200010752555
characterization of an iridescent virus isolated from gryllus bimaculatus (orthoptera: gryllidae).we have isolated an iridescent virus from commercially produced colonies of gryllus bimaculatus in germany, which showed apparent mortality. transmission electron microscopy studies on adult cricket specimens revealed the paracrystalline assembly of icosahedral virus particles in the cytoplasm of hypertrophied abdominal fat body cells. the infecting agent could be cultivated in the lepidopteran cell line sf-9, where it caused cytopathogenic effects such as cell hypertrophy, cytoplasmic vacuoliza ...200111161994
sequence analysis of the complete genome of an iridovirus isolated from the tiger frog.we have isolated a tiger frog virus (tfv) from diseased tiger frogs, rana tigrina rugulosa. the genome was a linear double-stranded dna of 105,057 basepairs in length with a base composition of 55.01% g+c. about 105 open reading frames were identified with coding capacities for polypeptides ranging from 40 to 1294 amino acids. computer-assisted analyses of the deduced amino acid sequences revealed that 39 of 105 putative gene products showed significant homology to functionally characterized pro ...200211878922
ranaviruses (family iridoviridae): emerging cold-blooded killers.although possessing novel replicative and structural features, the family iridoviridae has not been as extensively studied as other families of large, dna-containing viruses (e.g., poxviridae and herpesviridae). this oversight most likely reflects the inability of iridoviruses to infect mammals and birds, and their heretofore low pathogenicity among cold-blooded animals and invertebrates. in fact, the original frog virus isolates (e.g., frog viruses 1-3) would likely have been considered orphan ...200211958449
antigenic characterization of a marine fish iridovirus from grouper, epinephelus spp.iridoviruses, recognized as causative agents of serious systemic diseases, have been identified from more than 20 fish species. antigenic properties of a pathogenic iridovirus isolated from grouper, epinephelus spp., in singapore (sgiv) were investigated using rabbit igg against the virus. antisera were prepared by immunization of rabbit with purified virions. the rabbit igg was purified from antiserum using a protein a-agarose column and adsorbed onto acetone-dried grouper (gp) cells. the viral ...200212367733
what's your diagnosis? ranavirus infection. 200312601385
cladistic analysis of iridoviruses based on protein and dna sequences.cladograms of iridoviruses were inferred from bootstrap analysis of molecular data sets comprising all published protein and dna sequences of the major capsid protein, atpase and dna polymerase genes of members of the iridoviridae family iridovirus. all data sets yielded cladograms supporting the separation of the iridovirus, ranavirus and lymphocystivirus genera, and the cladogram based on data derived from major capsid proteins further divided both the iridovirus and ranavirus genera into two ...200314579177
comparative genomic analyses of frog virus 3, type species of the genus ranavirus (family iridoviridae).frog virus 3 (fv3) is the type species member of the genus ranavirus (family iridoviridae). to better understand the molecular mechanisms involved in the replication of fv3, including transcription of its highly methylated dna genome, we have determined the complete nucleotide sequence of the fv3 genome. the fv3 genome is 105903 bp long excluding the terminal redundancy. the g + c content of fv3 genome is 55% and it encodes 98 nonoverlapping potential open reading frames (orfs) containing 50-129 ...200415165820
comparison of the eif-2alpha homologous proteins of seven ranaviruses (iridoviridae).the alpha-subunit of the eukaryotic initiation factor 2 (eif-2alpha) is a key component of the translation machinery of the cell. in response to cellular stress such as viral infections, eif-2alpha is phosphorylated by double-stranded rna-dependent protein kinase (pkr) leading to the inhibition of cellular protein synthesis. the importance of eif-2alpha as a regulatory mechanism for protein synthesis is illustrated by the wide variety of strategies employed by viruses to down-regulate pkr. thus, ...200111778703
response of the italian agile frog (rana latastei) to a ranavirus, frog virus 3: a model for viral emergence in naïve populations.ranavirus (family iridoviridae) is a genus of pathogens of poikilotherms, and some ranaviruses may play a role in widespread mortality of amphibians. ecology of viral transmission in amphibians is poorly known but can be addressed through experimentation in the laboratory. in this study, we use the ranavirus frog virus 3 (fv3) as an experimental model for pathogen emergence in naive populations of tadpoles. we simulated emerging disease by exposing tadpoles of the italian agile frog (rana latast ...200415650083
adaptive immunity and histopathology in frog virus 3-infected xenopus.xenopus has been used as an experimental model to evaluate the contribution of adaptive cellular immunity in amphibian host susceptibility to the emerging ranavirus fv3. conventional histology and immunohistochemistry reveal that fv3 has a strong tropism for the proximal tubular epithelium of the kidney and is rarely disseminated elsewhere in xenopus hosts unless their immune defenses are impaired or developmentally immature as in larvae. in such cases, virus is found widespread in most tissues. ...200515680432
transmission of the ambystoma tigrinum virus to alternative hosts.ambystoma tigrinum virus (atv) is a lethal virus originally isolated from sonora tiger salamanders ambystoma tigrinum stebbinsi in the san rafael valley in southern arizona. usa. atv is implicated in several salamander epizootics. we attempted to transmit atv experimentally to fish and amphibians by injection, water bath exposure, or feeding to test whether atv can cause clinical signs of infection or be recovered from exposed individuals that do not show clinical signs. cell culture and polymer ...200111710549
ranavirus-associated morbidity and mortality in a group of captive eastern box turtles (terrapene carolina carolina).seven captive eastern box turtles (terrapene carolina carolina) from a large collection of north american chelonians in north carolina became acutely ill in the fall of 2002. five of the turtles died. clinical signs included cutaneous abscessation, oral ulceration or abscessation (or both), respiratory distress, anorexia, and lethargy. the predominant postmortem lesion was fibrinoid vasculitis of various organs, including skin, mucous membranes, lungs, and liver. no inclusion bodies were detecte ...200415732597
inactivation of frog virus 3 and channel catfish virus by esculentin-2p and ranatuerin-2p, two antimicrobial peptides isolated from frog skin.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 ran ...200111601906
promoter activity in the 5' flanking regions of the bohle iridovirus icp 18, icp 46 and major capsid protein genes.bohle iridovirus (biv) belongs to the genus ranavirus, of which frog virus 3 (fv-3) is the type species. we are developing biv as a recombinant viral delivery vector, and as a first step we located specific biv promoter sequences to drive foreign gene expression in the recombinant virus. by comparison with fv-3 sequences, the genes encoding icp 18 and icp 46 in biv were identified and sequenced. putative promoter regions of these two early genes and of the major capsid protein (mcp) gene were id ...200515841340
identification of a bohle iridovirus thymidine kinase gene and demonstration of activity using vaccinia recent years interest in the family iridoviridae has been renewed by the identification of a number of viruses, particularly from the genus ranavirus, associated with disease in a range of poikilotherms. ranaviruses have been isolated from amphibian, piscine and reptilian species. here we describe an open reading frame (orf) identified in the genome of bohle iridovirus (biv) which contains a nucleotide binding motif conserved within the thymidine kinase (tk) genes of iridoviruses from other g ...200515883656
giant toads bufo marinus in australia and venezuela have antibodies against 'ranaviruses'.a serological survey was conducted for antibodies against 'ranaviruses' in the giant toad bufo marinus in australia and venezuela. sera containing antibodies against 'ranaviruses' were found in both countries. in australia positive antibodies were identified in populations throughout most of the known range of b. marinus. results were confirmed by immunofluorescence and immunoelectron microscopy where a characteristic staining pattern of 'ranaviruses' in infected cells was observed. whilst a 'ra ...19989676257
instability of frog virus 3 mrna in productively infected cells.cloned dna restriction fragments encoding representative frog virus 3 messages were used as probes to assess the stability of viral transcripts in infected fathead minnow cells. analysis of northern blot hybridization profiles confirmed earlier findings and revealed that in infected cells the steady-state level of representative frog virus 3 (fv3) messages increased throughout the replication cycle. however, when actinomycin d was added at 4 hr after infection to block the synthesis of new trans ...19948030277
epizootiology of sixty-four amphibian morbidity and mortality events in the usa, 1996-2001.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 ...200212381613
complete genome sequence of the grouper iridovirus and comparison of genomic organization with those of other iridoviruses.the complete dna sequence of grouper iridovirus (giv) was determined using a whole-genome shotgun approach on virion dna. the circular form genome was 139,793 bp in length with a 49% g + c content. it contained 120 predicted open reading frames (orfs) with coding capacities ranging from 62 to 1,268 amino acids. a total of 21% (25 of 120) of giv orfs are conserved in the other five sequenced iridovirus genomes, including dna replication, transcription, nucleotide metabolism, protein modification, ...200515681403
influence of temperature on ranavirus infection in larval salamanders ambystoma tigrinum.temperature strongly influenced percent mortality and time to death of salamanders exposed to the ambystoma tigrinum virus (iridovirus) (atv). most salamanders survived when exposed at 26 degrees c, whereas all died at 18 degrees c and nearly all died at 10 degrees c. some asymptomatic salamanders that survived 60 d at 10 or 26 degrees c were found to be carrying virus. polymerase chain reaction (pcr) confirmed the presence of virus in atv-exposed salamanders but was found to be less sensitive t ...200515819423
partial mapping and sequencing of a fish iridovirus genome reveals genes homologous to the frog virus 3 p31, p40 and human eif2alpha.iridovirus-like pathogens have been recognized as a cause of serious systemic diseases among feral, cultured and ornamental fish in the recent years. mortalities of fish due to systemic iridovirus infection reaching 30-100% were observed in europe, australia, japan and thailand. up to now, the molecular biology of these important pathogens has been poorly documented. to get better insights on the genomic organization of these piscine iridoviruses, we have constructed a cosmid viral dna library f ...199910509716
molecular characterization of iridoviruses isolated from sympatric amphibians and fish.iridoviruses infect invertebrates (primarily insects and crustaceans) and ectothermic vertebrates (fish, amphibians, and reptiles). identical, or nearly identical viruses, have been isolated from different animals within the same taxonomic class, indicating that infection by a given virus is not limited to a single species. although inter-class infections have been documented following experimental infection with vertebrate iridoviruses, it is not clear whether such infections occur in nature. h ...199910509715
phylogenetic analysis of the major capsid protein gene of iridovirus isolates from cultured flounders paralichthys olivaceus in 2003, 13 isolates of iridovirus were obtained from cultured flounders paralichthys olivaceus during epizootics in korea. the full open reading frames (orfs) encoding the major capsid protein (mcp) (1362 bp) from the 13 flounder iridoviruses (flivs) were sequenced and the deduced amino acid sequences were phylogenetically analyzed. phylogenetic analysis of the mcp revealed that all 13 flivs were the same species as rock bream iridovirus (rbiv), red sea bream iridovirus (rsiv), and infectious s ...200515997817
generation of a long-lasting, protective, and neutralizing antibody response to the ranavirus fv3 by the frog xenopus.xenopus serves as an experimental model to evaluate the contribution of adaptive immunity in host susceptibility to emerging ranaviral diseases that may contribute to amphibian population declines. it has been previously shown that following a secondary infection with the ranavirus frog virus 3 (fv3), adult xenopus more rapidly clear fv3 and generate specific anti-fv3 igy antibodies. we have further evaluated the potency and persistence of the xenopus antibody response against fv3. frogs inocula ...200616380162
genome of invertebrate iridescent virus type 3 (mosquito iridescent virus).iridoviruses (ivs) are classified into five genera: iridovirus and chloriridovirus, whose members infect invertebrates, and ranavirus, lymphocystivirus, and megalocytivirus, whose members infect vertebrates. until now, chloriridovirus was the only iv genus for which a representative and complete genomic sequence was not available. here, we report the genome sequence and comparative analysis of a field isolate of invertebrate iridescent virus type 3 (iiv-3), also known as mosquito iridescent viru ...200616912294
dose and host characteristics influence virulence of ranavirus infections.parasites play a prominent role in the ecology, evolution, and more recently, conservation of many organisms. for example, emerging infectious diseases, including a group of lethal ranaviruses, are associated with the declines and extinctions of amphibians around the world. an increasingly important basic and applied question is: what controls parasite virulence? we used a dose-response experiment with three laboratory-bred clutches of tiger salamander larvae (ambystoma tigrinum) to test how the ...200515891818
characterization of an early gene encoding for dutpase in rana grylio virus.dutpase (dut) is a ubiquitous and important enzyme responsible for regulating levels of dutp. here, an iridovirus dut was identified and characterized from rana grylio virus (rgv) which is a pathogen agent in pig frog. the dut encodes a protein of 164aa with a predicted molecular mass of 17.4 kda, and its transcriptional initiation site was determined by 5'race to start from the nucleotide a at 15 nt upstream of the initiation codon atg. sequence comparisons and multiple alignments suggested tha ...200716989917
inhibition of iridovirus protein synthesis and virus replication by antisense morpholino oligonucleotides targeted to the major capsid protein, the 18 kda immediate-early protein, and a viral homolog of rna polymerase ii.frog virus 3 (fv3) is a large dna virus that encodes approximately 100 proteins. although the general features of fv3 replication are known, the specific roles that most viral proteins play in the virus life cycle have not yet been elucidated. to address the question of viral gene function, antisense morpholino oligonucleotides (asmos) were used to transiently knock-down expression of specific viral genes and thus infer their role in virus replication. we designed asmos directed against the majo ...200717023014
proposals for a new classification of iridescent viruses.the need for comparative studies of iridoviruses to elucidate the relationships between them has been well appreciated. sixteen iridoviruses, including type species from each of the four recognized genera of the iridoviridae, were compared by restriction endonuclease characterization, hybridization to the major structural protein (msp) gene of an invertebrate iridescent virus (iv) isolate at various stringencies, pcr amplification of the msp gene region and by dot-blot hybridization studies. the ...19948207395
intracytoplasmic inclusions in circulating leukocytes from an eastern box turtle (terrapene carolina carolina) with iridoviral infection.a free-ranging adult female eastern box turtle (terrapene carolina carolina) was presented to the university of tennessee in october 2003 because of suspected trauma and blindness. physical examination revealed lethargy, clear ocular and nasal discharges, and white oral and laryngeal plaques. intracytoplasmic inclusions within heterophils and large mononuclear leukocytes were observed on routine blood smear examination. postmortem findings included necrosis of epithelial and parenchymal cells wi ...200617092902
improvement and observation of immunoelectron microscopic method for the localization of frog rana grylio virus (rgv) in infected fish this paper, to understand the roles of amorphous structures which were observed within the viromatrix of rana grylio virus (rgv), an improved immunoelectron microscopy (iem) method was developed to detect the localization of rgv in carp epithelipma papulosum cyprinid (epc) cells. infected epc cells were fixed with 4% paraformaldehyde-0.25% glutaraldehyde mixture, dehydrated completely, and embedded in lr white resin. this method allowed good ultrastructural preservation and specific labeling ...200717095234
emerging epidemic diseases of frogs in britain are dependent on the source of ranavirus agent and the route of exposure.a series of transmission studies was conducted to investigate the aetiology, or aetiologies, of emerging fatal epidemic disease syndromes affecting the common frog (rana temporaria) in britain. the syndromes, characterized by skin ulceration or systemic haemorrhages, were induced upon exposure to lesion homogenates or cultured ranavirus. the re-isolation of ranavirus from experimentally affected frogs fulfilled koch's postulates. aeromonas hydrophila, previously associated with similar lesions, ...200717181914
characterization of primary and memory cd8 t-cell responses against ranavirus (fv3) in xenopus mammals, resistance to primary and secondary viral infections critically involves major histocompatibility complex class i-restricted cytotoxic cd8+ t lymphocytes (ctls). although many gene homologues involved in ctl function have been identified in all vertebrate classes, antiviral ctl responses have been poorly characterized for ectothermic vertebrates. because of the threat of emerging wildlife viral diseases to global biodiversity, fundamental research on comparative viral immunity has be ...200717182687
evidence for emergence of an amphibian iridoviral disease because of human-enhanced spread.our understanding of origins and spread of emerging infectious diseases has increased dramatically because of recent applications of phylogenetic theory. iridoviruses are emerging pathogens that cause global amphibian epizootics, including tiger salamander (ambystoma tigrinum) die-offs throughout western north america. to explain phylogeographical relationships and potential causes for emergence of western north american salamander iridovirus strains, we sequenced major capsid protein and dna me ...200515643965
first identification of a ranavirus from green pythons (chondropython viridis).ten juvenile green pythons (chondropython viridis) died or were euthanized shortly after having been illegally imported into australia from indonesia in 1998. histologic examination of two of the three snakes that died revealed moderately severe chronic ulceration of the nasal mucosa and focal or periacinar degeneration and necrosis of the liver. in addition there was severe necrotizing inflammation of the pharyngeal submucosa accompanied by numerous macrophages, heterophils, and edema. an irido ...200212038121
occurrence of an invertebrate iridescent-like virus (iridoviridae) in reptiles.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 ha ...200111765804
mercury bioaccumulation in green frog (rana clamitans) and bullfrog (rana catesbeiana) tadpoles from acadia national park, maine, usa.mercury contamination in the northeastern united states, including acadia national park (anp; me, usa), is well documented and continues to be a public health issue of concern. mercury contamination of wild amphibians has received little attention, however, despite reports of worldwide population declines. here, we report total hg and methyl hg (mehg) concentrations for water, sediment, and green frog (rana clamitans) and bullfrog (rana catesbeiana) tadpoles (age, approximately one year) from an ...200717269468
experimental transmission of a ranavirus disease of common toads (bufo bufo) to common frogs (rana temporaria).during investigations of epidemic frog mortality in britain, a novel fatal systemic haemorrhagic disease of common toads was discovered. this disease resembles a systemic haemorrhagic disease of common frogs in britain, which is one of a range of fatal disease syndromes, characterized by systemic haemorrhages, skin ulceration or a combination of these lesions, caused by ranavirus infection. ranavirus previously isolated from diseased toads was inoculated into common frogs to evaluate if this vir ...200717274859
isolation of a ranavirus from a gecko (uroplatus fimbriatus).a virus was isolated from the liver and stomach of a leaf-tailed gecko (uroplatus fimbriatus) with granulomatous lesions on the tongue and hepatitis. the virus was identified as an iridovirus on the basis of morphology by electron microscopy, restriction endonuclease assay, and sequencing of a large portion of the major capsid protein gene. comparative analysis revealed that this isolate is related to frog virus 3, the type species of the genus ranavirus.200517323572
temporal and differential gene expression of singapore grouper iridovirus.singapore grouper iridovirus (sgiv), an iridovirus in the genus ranavirus, is a major pathogen that results in significant economic losses in grouper aquaculture. to investigate further its infective mechanisms, for the first time, a viral dna microarray was generated for the sgiv genome to measure the expression of its predicted open reading frames simultaneously in vitro. by using the viral dna microarray, the temporal gene expression of sgiv was characterized and the dna microarray data were ...200616963749
ranavirus-associated mass mortality in imported red tailed knobby newts (tylototriton kweichowensis): a case report.a mass die-off of imported red tailed knobby newts (tylototriton kweichowensis) occurred in 2004 in belgium and the netherlands. in addition to massive infection with rhabdias tokyoensis, ranavirus was isolated from three dead newts examined virologically and the gene coding for the major capsid protein of the virus was sequenced. the isolate showed 99.8% similarity to the published sequence of frog virus 3. upon experimental infection of axolotls (ambystoma mexicanum) with this isolate, no mark ...200817449300
frog virus 3 infection, cultured american bullfrogs. 200717479910
experimental transmission and induction of ranaviral disease in western ornate box turtles (terrapene ornata ornata) and red-eared sliders (trachemys scripta elegans).an experimental transmission study was designed to determine whether a causal relationship exists between a ranavirus (bstrv) isolated from a burmese star tortoise that died and the lesions observed in that tortoise. a pilot study was performed with 3 box turtles (terrapene ornata ornata) and 3 red-eared sliders (ress; trachemys scripta elegans) to assess their suitability in a larger study. based on the outcome of this study, ress were selected, and 2 groups of 4 ress received either an oral (p ...200717491069
five amphibian mortality events associated with ranavirus infection in south central ontario, canada.using field, molecular and histological methods, an epizootic, systemic disease causing death within wood frog rana sylvatica tadpoles and leopard frog rana pipiens metamorphs at 3 different locations within southern ontario, canada, has been investigated. our results demonstrated that the probable cause of this disease was a ranavirus. affected amphibians were found to exhibit necrosis within the hematopoietic cells. liver tissue samples were found positive for the virus by pcr amplification of ...200516385802
mitochondrion-mediated apoptosis induced by rana grylio virus infection in fish cells.a fish cell line, fathead minnow (fhm) cell, was used to investigate the alteration of mitochondrial dynamics and the mechanism of apoptosis under rana grylio virus (rgv) infection. microscopy observations, flow-cytometry analysis and molecular marker detection revealed the apoptotic fate of the rgv-infected cells. some typical apoptotic characteristics, such as chromatin condensation, dna fragmentation and mitochondrial fragmentation, were observed, and significantly morphological changes of mi ...200717551838
a broadly applicable method to characterize large dna viruses and adenoviruses based on the dna polymerase gene.many viral pathogens are poorly characterized, are difficult to culture or reagents are lacking for confirmatory diagnoses. we have developed and tested a robust assay for detecting and characterizing large dna viruses and adenoviruses. the assay is based on the use of degenerate pcr to target a gene common to these viruses, the dna polymerase, and sequencing the products.200616608526
amphibian ocular malformation associated with frog virus 3.during an on-going amphibian ecology study, a free-ranging american bullfrog (rana catesbeiana) metamorph was captured in a pitfall trap adjacent to a constructed farm pond at the plateau research and education center (prec) on the cumberland plateau near crossville, tennessee, usa. grossly, the right eye was approximately 50% the size of the left. stereo and light microscopic examination revealed two granulomas within the orbit. electron microscopic examination revealed virus particles scattere ...200817604194
comparative genomic analysis of the family iridoviridae: re-annotating and defining the core set of iridovirus genes.members of the family iridoviridae can cause severe diseases resulting in significant economic and environmental losses. very little is known about how iridoviruses cause disease in their host. in the present study, we describe the re-analysis of the iridoviridae family of complex dna viruses using a variety of comparative genomic tools to yield a greater consensus among the annotated sequences of its members.200717239238
characterization of a late gene encoding for mcp in soft-shelled turtle iridovirus (stiv).major caspid protein (mcp) is the major structural component of virus particles and revealed to be very responsible for classification of new tentative iridovirus isolates. in this paper, the complete sequences of mcp gene was firstly identified and characterized from soft-shelled turtle iridovirus (stiv). the mcp, classified as a late transcript by drug inhibition, encodes a protein of 463 aa with a predicted molecular weight of 50kda. indirect immunofluorescence (iif) and virus neutralization ...200717706827
phylogenetic concordance analysis shows an emerging pathogen is novel and endemic.distinguishing whether pathogens are novel or endemic is critical for controlling emerging infectious diseases, an increasing threat to wildlife and human health. to test the endemic vs. novel pathogen hypothesis, we present a unique analysis of intraspecific host-pathogen phylogenetic concordance of tiger salamanders and an emerging ranavirus throughout western north america. there is significant non-concordance of host and virus gene trees, suggesting pathogen novelty. however, non-concordance ...200717850337
bohle iridovirus as a vector for heterologous gene expression.the large double-stranded dna (ds dna) viruses were among the first to be used to construct recombinant viruses, but to date this has not been achieved with any members of the ds dna virus family, iridoviridae. we identified a non-essential gene, the viral homologue of eukaryotic initiation factor 2alpha (eif-2alpha), in bohle iridovirus (biv, genus ranavirus). a recombinant biv was constructed with the neomycin resistance gene and the bufo marinus (cane toad) adult globin gene inserted into the ...200717904650
expression and serological application of a capsid protein of an iridovirus isolated from rock bream, oplegnathus fasciatus (temminck & schlegel).iridoviruses infect a wide variety of wild and cultured fish. those iridoviruses belonging to the genus ranavirus, in the iridoviridae family, cause systemic disease in infected animals with a high morbidity and mortality. this paper reports the cloning, sequencing, and expression of the rock bream iridovirus (rbiv) major capsid protein (mcp) in an escherichia coli expression system for subsequent immunological studies. the completeness of the expressed protein was confirmed by peptide mass fing ...200717958613
viral dna sequences of genes encoding the atpase and the major capsid protein of tropical iridovirus isolates which are pathogenic to fishes in japan, south china sea and southeast asian countries.tropical iridovirus infection causes severe epizootic resulting in mass mortalities and large economic losses in freshwater ornamental fishes cultured in southeast asian countries, in wild fish seedlings captured in south china sea, and in marine fishes farmed in japan, singapore, and thailand. all of tropical iridovirus-infected fishes histopathologically showed the systemic formation of inclusion body-bearing cells and necrosis of virus-infected splenocytes and hematopoietic cells. we designed ...200212417946
susceptibility of the endangered california tiger salamander, ambystoma californiense, to ranavirus infection.emerging infectious diseases are implicated in the declines and extinctions of amphibians worldwide. ranaviruses in the family iridoviridae are a global concern and have caused amphibian die-offs in wild populations in north america, europe, south america, and in commercial populations in asia and south america. the movement of amphibians for bait, food, pets, and research provides a route for the introduction of ranaviruses into naive and potentially endangered species. in this report, we demon ...200717495315
immunohistochemical demonstration of ranavirus antigen in the tissues of infected frogs (rana temporaria) with systemic haemorrhagic or cutaneous ulcerative disease.ranavirus disease emerged as a cause of annually recurring epidemic mortality of common frogs (rana temporaria) in britain in the late-1980s. affected frogs present with a peracute disease characterized by systemic haemorrhage, or with a chronic disease characterized by skin ulceration, but no internal gross lesions. common toads (bufo bufo) have also been found with haemorrhagic ranavirus disease. in order to investigate possible differences in the pathogenesis of ranavirus infection for each m ...200817983626
xenopus laevis: a possible vector of ranavirus infection?frog virus 3 (fv3) or fv3-like viruses (iridoviridae) infect a wide range of amphibian species, and they are becoming increasingly and causally associated with amphibian disease outbreaks worldwide. we have established the frog xenopus laevis as an experimental model to study host defense and pathogenesis of fv3 infection. although x. laevis adults usually clear fv3 infection within a few weeks, viral dna has been detected in the kidneys several months after they had been experimentally infected ...200717984259
habitat fragmentation as a result of biotic and abiotic factors controls pathogen transmission throughout a host population.1. the hypothesis that habitat fragmentation (biotic or abiotic) alters the transmission of disease within a population is explored using field data from a well-studied amphibian-pathogen system. 2. we used the ambystoma tigrinum-a. tigrinum virus (atv) model system to show how habitat fragmentation as a result of emergent vegetation and habitat management affects disease transmission dynamics in ponds across a landscape. 3. we quantified variation in atv infection over time and across the lands ...200818005032
frog virus 3-like infections in aquatic amphibian communities.frog virus 3 (fv3) and fv3-like viruses, are members of the genus ranavirus (family iridoviridae), and they have been associated with infectious diseases that may be contributing to amphibian population declines. we examined the mode of transmission of an fv3-like virus, and potential hosts and reservoirs of the virus in a local amphibian community. using the polymerase chain reaction to detect infected animals, we found an fv3-like virus in south-central ontario, canada, amphibian communities, ...200818263826
inhibition of reporter gene and iridovirus-tiger frog virus in fish cell by rna interference.we describe the specific silencing of reporter gene lacz in fhm cells (muscle cells of fathead minnow, a fish cell line) by either expressing small hairpin rnas (shrnas) from plasmids or transfecting small interfering rnas (sirnas) transcribed in vitro. two types of dsrnas could inhibit reporter gene expression, and sirnas were more effective, while both of them worked very well in hela cells. sirnas were tested for silencing expression of the major capsid protein (mcp) encoded by tiger frog vir ...200515932766
antimicrobial peptide defenses in the salamander, ambystoma tigrinum, against emerging amphibian peptides were collected from living ambystoma tigrinum larvae and adults and tested against two emerging pathogens, batrachochytrium dendrobatidis and the ambystoma tigrinum virus (atv), as well as bacteria isolated from a. tigrinum. natural mixtures of skin peptides were found to inhibit growth of b. dendrobatidis, staphylococcus aureus, and klebsiella sp., but activity against atv was unpredictable. skin peptides collected from salamanders held at three environmentally relevant temperatur ...200818436656
properties of iridoviruses from ornamental iridovirus from 2 species of freshwater tropical imported fish was examined for its antigenic and biochemical properties and virulence for 3 species of food fish. the virus was found in both guppy (poecilia reticulata) and doctor fish (labroides dimidatus). the virus replicated in numerous fish cell lines including bf-2, cco and epc. virus titers reached 10(8) tcid50/ml in each cell line. the virions had similar size and morphology to those previously reported to cause systemic infections amo ...19958581016
anthropogenic influence on prevalence of 2 amphibian pathogens. 200818598658
inactivation of viruses infecting ectothermic animals by amphibian and piscine antimicrobial peptides.the ability of five purified amphibian antimicrobial peptides (dermaseptin-1, temporin a, magainin i, and ii, pgla), crude peptide fractions isolated from the skin of rana pipiens and r. catesbeiana, and four antimicrobial peptides (amps) from hybrid striped bass (piscidin-1n, -1h, -2, and -3) were examined for their ability to reduce the infectivity of channel catfish virus (ccv) and frog virus 3 (fv3). all compounds, with the exception of magainin i, markedly reduced the infectivity of ccv. in ...200415193922
rapid differentiation of australian, european and american ranaviruses based on variation in major capsid protein gene sequence.epizootic haematopoietic necrosis virus (ehnv), bohle iridovirus (biv) and wamena virus (wv) cause serious diseases in fish, amphibians and snakes, respectively but are restricted to australasia. european catfish virus (ecv) and sheatfish virus (esv) have caused epizootics in fish on farms in continental europe. currently there are no simple or readily available methods to distinguish these viruses, which are in the iridoviridae. they are culturally, morphologically and antigenically very simila ...200212030764
characterization of an iridovirus from the cultured pig frog rana grylio with lethal syndrome.three virus isolates, rgv-9506, rgv-9807 and rgv-9808, were obtained from cultured pig frogs rana grylio undergoing lethal infections. previously, the first isolate, rgv-9506, was shown to be an iridovirus based on ultrastructural and morphological studies. in the present study, the original isolate, along with 2 recent ones, were more extensively characterized by experimental infection studies, histopathology, electron microscopy, serological reactivity, gel electrophoresis of viral polypeptide ...200111843137
concurrent infection with ranavirus, batrachochytrium dendrobatidis, and aeromonas in a captive anuran colony.four species (dendrobates auratus, phyllobates terribilis, pyxicephalus adspersus, and rhacophorus dennysi) of captive anurans with a clinical history of lethargy and inappetence were found dead and were submitted for necropsy. gross lesions included irregular patches of sloughed skin and rare dermal ulcerations. histologic findings included epidermal proliferation that was most pronounced on the digits and that included intracytoplasmic chytrid organisms. bacteria were often associated with the ...200818817009
transcriptional response of mexican axolotls to ambystoma tigrinum virus (atv) infection.very little is known about the immunological responses of amphibians to pathogens that are causing global population declines. we used a custom microarray gene chip to characterize gene expression responses of axolotls (ambystoma mexicanum) to an emerging viral pathogen, ambystoma tigrinum virus (atv).200818937860
electron microscopic examination of the viromatrix of rana grylio virus in a fish cell line.rana grylio virus (rgv), a ranavirus belonging to the family iridoviridae, assembles in the viromatrix which is a factory for viral genome replication and particle assembly. ultrastructural studies of the viromatrix will clarify the pathway of assembly. the viromatrix and quantitative changes in rgv infected epithelipma papulosum cyprini (epc) cells, one of fish cell lines, were studied by electron microscopy. it was shown that viromatrices were adjacent to the nucleus, and the electron density ...200616310866
family iridoviridae: poor viral relations no longer.members of the family iridoviridae infect a diverse array of invertebrate and cold-blooded vertebrate hosts and are currently viewed as emerging pathogens of fish and amphibians. iridovirid replication is unique and involves both nuclear and cytoplasmic compartments, a circularly permuted, terminally redundant genome that, in the case of vertebrate iridoviruses, is also highly methylated, and the efficient shutoff of host macromolecular synthesis. although initially neglected largely due to the ...200919216437
transcription and temporal cascade in chilo iridescent virus infected cells.chilo iridescent virus (civ) is the type species for genus iridovirus, and belongs to the family iridoviridae. members of this family are large, isometric, cytoplasmic dna viruses. our laboratory has established that civ replicates productively in the cotton boll weevil, anthonomus grandis. given the economic importance of this host and the dearth of knowledge on this virus, we have initiated host-virus interaction and molecular studies on civ. this report focuses on regulation of transcription ...200111765918
the role of amphibian antimicrobial peptides in protection of amphibians from pathogens linked to global amphibian declines.amphibian species have experienced population declines and extinctions worldwide that are unprecedented in recent history. many of these recent declines have been linked to a pathogenic skin fungus, batrachochytrium dendrobatidis, or to iridoviruses of the genus ranavirus. one of the first lines of defense against pathogens that enter by way of the skin are antimicrobial peptides synthesized and stored in dermal granular glands and secreted into the mucus following alarm or injury. here, i revie ...200919327341
pathologic findings in larval and juvenile anurans inhabiting farm ponds in tennessee, usa.amphibian populations are declining globally, yet general pathologic surveys for free-ranging amphibians are uncommon. pathologic surveys are necessary to provide insight into the impacts of humans on emergence of pathogens in amphibian populations. during 2005, 104 american bullfrog (rana catesbeiana) and 80 green frog (rana clamitans) larvae and 40 green frog juveniles were collected from farm ponds in tennessee, and complete necropsies were performed. diagnostic testing included bacterial cul ...200919395741
susceptibility of pike esox lucius to a panel of ranavirus order to study the pathogenicity of ranaviruses to a wild european freshwater fish species, pike esox lucius fry were challenged with the following ranavirus isolates: epizootic haematopoietic necrosis virus (ehnv), european sheatfish virus (esv), european catfish virus (ecv), pike-perch iridovirus (ppiv), new zealand eel virus (nzeelv) and frog virus 3 (fv3). the fry were infected using bath challenge at 12 and 22 degrees c. significant mortalities were observed at 12 degrees c for ehnv, esv ...200919402450
tiger frog virus can infect zebrafish cells for studying up- or down-regulated genes by proteomics approach.tiger frog virus (tfv), a member of the iridovirus family, causes high mortality of cultured tiger frog tadpoles in southern china. to better understand tfv infection and its interaction with host cells, zebrafish embryonic fibroblast (zf4) cells, a stable polyploid cell line with most clear genetic map, was used for our present study. our results showed that tfv caused typical lytic plaque forming cytopathic effect (cpe) and that various stages of viral proliferation were observed using electro ...200919409947
combined effects of atrazine and chlorpyrifos on susceptibility of the tiger salamander to ambystoma tigrinum virus.several hypotheses have been examined as potential causes of global amphibian declines, including emerging infectious diseases and environmental contaminants. although these factors are typically studied separately, animals are generally exposed to both stressors simultaneously. we examined the effects of the herbicide atrazine and the insecticide chlorpyrifos on the susceptibility of tiger salamander larvae, ambystoma tigrinum, to a viral pathogen, ambystoma tigrinum virus (atv). environmentall ...200919415385
first case of ranavirus-associated morbidity and mortality in natural populations of the south american frog atelognathus patagonicus.atelognathus patagonicus is an endangered leptodactylid frog endemic to a small region in and around laguna blanca national park in northern patagonia, argentina. all of the lakes and small ponds of the region (except laguna blanca itself) contain a. patagonicus and in all but one of these lakes the species shows clinical signs of a previously undiagnosed disease, the characteristics of which suggested a ranavirus. we collected symptomatic and asymptomatic a. patagonicus frogs and tadpoles from ...200617067077
molecular characterization of a ranavirus isolated from largemouth bass micropterus iridovirus, isolated from largemouth bass micropterus salmoides following a die-off among adult fish and provisionally designated largemouth bass virus (lmbv), was characterized by analysis of viral protein synthesis in infected cells, viral dna restriction fragment length polymorphisms (rflp), and sequence determination of the major capsid protein and viral dna methyltransferase genes. all 3 approaches yielded results consistent with the suggestion that lmbv was a member of the genus ranavir ...199910494500
diagnostic and molecular evaluation of three iridovirus-associated salamander mortality 1998 viruses were isolated from tiger salamander larvae (ambystoma tigrinum diaboli and a. tigrinum melanostictum) involved in north dakota and utah (usa) mortality events and spotted salamander (a. maculatum) larvae in a third event in maine (usa). although sympatric caudates and anurans were present at all three sites only ambystomid larvae appeared to be affected. mortality at the north dakota site was in the thousands while at the utah and maine sites mortality was in the hundreds. sick l ...200314567216
induction of apoptosis in frog virus 3-infected cells.the ability of frog virus 3 (fv3), the type species of the family iridoviridae, to induce apoptosis was examined by monitoring dna cleavage, chromatin condensation, and cell-surface expression of phosphotidylserine (ps) in fathead minnow (fhm) and baby hamster kidney (bhk) cells. in productively infected fhm cells, dna fragmentation was first noted at 6-7 h postinfection and was clearly seen by 17 h postinfection, while chromatin condensation was detected at 8.5 h postinfection. as with some oth ...200312642103
spatial and temporal patterns of ambystoma tigrinum virus (atv) prevalence in tiger salamanders ambystoma tigrinum nebulosum.amphibian ranaviruses have been documented as causes of mass mortality in amphibian populations throughout the world. the temporal and spatial dynamics of ranavirus infections when epidemics are not apparent remains unclear. to address this question, we collected tissue samples from 2003 to 2006 in 4 geographically separated tiger salamander ambystoma tigrinum nebulosum host populations on the kaibab plateau in northern arizona. we tested for ambystoma tigrinum virus (atv), a lethal ranavirus of ...200919593927
ranavirus in wild edible frogs pelophylax kl. esculentus in denmark.a survey for the amphibian pathogens ranavirus and batrachochytrium dendrobatidis (bd) was conducted in denmark during august and september 2008. the public was encouraged via the media to register unusual mortalities in a web-based survey. all members of the public that registered cases were interviewed by phone and 10 cases were examined on suspicion of disease-induced mortality. all samples were negative for bd. ranavirus was isolated from 2 samples of recently dead frogs collected during a m ...200919593928
experimental challenge and clinical cases of bohle iridovirus (biv) in native australian anurans.ranaviruses have been observed with increasing frequency amongst poikilothermic vertebrate hosts. the impact of ranaviruses upon amphibian populations has remained largely unknown. a gene probe for bohle iridovirus (biv) based upon primers designed to detect epizootic haematopoietic necrosis virus (ehnv) was constructed. a pcr and dot-blot system was used successfully in screening for the presence of biv nucleic acid in digested formalin-fixed, paraffin-embedded amphibian tissues. juvenile frogs ...200212078986
ranavirus outbreak in north american bullfrogs (rana catesbeiana), japan, 2008. 200919624949
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