Pathogenesis of mixed infection by Spironucleus sp. and Citrobacter freundii in freshwater angelfish Pterophyllum scalare.

The present study was carried out to identify and describe the pathology of the freshwater angelfish Pterophyllum scalare during chronic mortality in an in-door aquaculture system. Scraping of the integument and gills and the collection of intestinal contents to search for external and internal parasites were performed. Kidneys were collected aseptically for the microbiological analysis and the isolates were subjected to antibiotics to test for susceptibility. Subsequently, necropsy for macroscopic assessment and collection of internal organs for histopathology were performed. The fish exhibited lethargy, lip tumor, hemorrhage and liver granuloma. No ectoparasites were diagnosed. Endoparasites of the genus Spironucleus were found in large numbers in the intestine of the affected fish. In the microbiological analysis, Citrobacter freundii was isolated from the kidney and identified by colony PCR. This bacterium showed susceptibility to three of the eight antibiotics evaluated: ciprofloxacin, cefoxitin and tetracycline. For the pathological analysis, liver and spleen granulomas were present. In the intestinal tissue, a large and unusual amount of mast cells and their free granules were described and discussed in detail. The present study showed that mast cells play an important role during the chronic infection of freshwater angelfish.

A wide diversity of previously undetected free-living relatives of diplomonads isolated from marine/saline habitats.

Over the last 15 years classical culturing and environmental PCR techniques have revealed a modest number of genuinely new major lineages of protists; however, some new groups have greatly influenced our understanding of eukaryote evolution. We used culturing techniques to examine the diversity of free-living protists that are relatives of diplomonads and retortamonads, a group of evolutionary and parasitological importance. Until recently, a single organism, Carpediemonas membranifera, was the only representative of this region of the tree. We report 18 new isolates of Carpediemonas-like organisms (CLOs) from anoxic marine sediments. Only one is a previously cultured species. Eleven isolates are conspecific and were classified within a new genus, Kipferlia n. gen. The remaining isolates include representatives of three other lineages that likely represent additional undescribed genera (at least). Small-subunit ribosomal RNA gene phylogenies show that CLOs form a cloud of six major clades basal to the diplomonad-retortamonad grouping (i.e. each of the six CLO clades is potentially as phylogenetically distinct as diplomonads and retortamonads). CLOs will be valuable for tracing the evolution of diplomonad cellular features, for example, their extremely reduced mitochondrial organelles. It is striking that the majority of CLO diversity was undetected by previous light microscopy surveys and environmental PCR studies, even though they inhabit a commonly sampled environment. There is no reason to assume this is a unique situation - it is likely that undersampling at the level of major lineages is still widespread for protists.

Cell morphology and formal description of Ergobibamus cyprinoides n. g., n. sp., another Carpediemonas-like relative of diplomonads.

About 20 new isolates of Carpediemonas-like organisms (CLOs) have been reported since 2006. Small subunit rRNA gene phylogenies divide CLOs into six major clades: four contain described exemplars (i.e. Carpediemonas, Dysnectes, Hicanonectes, and Kipferlia), but two include only undescribed organisms. Here we describe a representative of one of these latter clades as Ergobibamus cyprinoides n. g., n. sp., and catalogue its ultrastructure. Ergobibamus cyprinoides is a bean-shaped biflagellated cell, 7-11.5 µm long, with a conspicuous groove. Instead of classical mitochondria there are cristae-lacking rounded organelles 300-400 nm in diameter. The posterior flagellum has a broad ventral vane and small dorsal vane. There are normally four basal bodies, two non-flagellated. There is one anterior root (AR), containing six microtubules. The posterior flagellar apparatus follows the "typical excavate" pattern of a splitting right root supported by fibres "I,""B," and "A," a "composite" fibre, a singlet root, and a left root (LR) with a "C" fibre. The B fibre originates against the LR--a synapomorphy of the taxon Fornicata--supporting the assignation of Ergobibamus to Fornicata, along with diplomonads, retortamonads, and other CLOs. Distinctive features of E. cyprinoides include the complexity of the AR, which is intermediate between Hicanonectes, and Carpediemonas and Dysnectes, and a dorsal extension of the C fibre.

Systemic spironucleosis in 2 immunodeficient rhesus macaques (Macaca mulatta).

Spironucleus spp are parasites of fish and terrestrial vertebrates, including mice and turkeys, that rarely cause extraintestinal disease. Two rhesus macaques (Macaca mulatta) were experimentally inoculated with simian immunodeficiency virus mac251. Both progressed to simian acquired immune deficiency syndrome within 1 year of inoculation and developed systemic protozoal infections in addition to common opportunistic infections, including rhesus cytomegalovirus, rhesus lymphocryptovirus, and rhesus adenovirus. In the first case, the protozoa were associated with colitis, multifocal abdominal abscessation, and lymphadenitis. In the second case, they were one of a number of organisms associated with extensive pyogranulomatous pneumonia and colitis. Ultrastructural, molecular, and phylogenetic analysis revealed the causative organism to be a species of Spironucleus closely related to Spironucleus meleagridis of turkeys. This report is the first of extraintestinal infection with Spironucleus sp in higher mammals and expands the list of opportunistic infections found in immunocompromised rhesus macaques.

The Phylogenetic Position of Spironucleus sp. (Diplomonadida: Hexamitidae) from the Intestine of Chinese Sleeper Perccottus glenii Dybowski, 1877 (Actinopterygii: Odontobutidae).

INTRODUCTION: The Chinese (Amur) sleeper (Perccottus glenii Dybowski, 1877) (Actinopterygii: Odontobutidae) is a freshwater fish species with high invasive potential. Diplomonads have been detected in the intestines of Chinese sleepers using light microscopy. AIM: The aim of this study was to identify the diplomonads in Chinese sleepers using molecular-genetic methods. MATERIALS AND METHODS: The fish used in this analysis were caught in the following bodies of water in Russia between 2014 and 2016: Lake Dolgoe, the floodplain of the Ingoda River (Amur River basin), the Tsna River (the Oka River basin), and the littoral of the Kotlin Island (Gulf of Finland). Partial sequences of small subunit rRNA genes were obtained for the intestinal diplomonads of Chinese sleeper. RESULTS: The analysis of all sequenced samples revealed the presence of Spironucleus salmonis Moore, 1922; other Spironucleus species were not found in the sampled fish. With 82% probability, the sampled sequences of diplomonads from Chinese sleeper formed a separate cluster in the clade of S. salmonis on the phylogenetic tree. CONCLUSION: This is the first record of S. salmonis in fish in the family Odontobutidae.

Phylogeny of spironucleus (eopharyngia: diplomonadida: hexamitinae).

Diplomonad flagellates from the genera Spironucleus and Hexamita (Hexamitinae) inhabit the digestive tract of a variety of animal hosts, some as important pathogens, and others as commensals. Species descriptions of many diplomonads have been based on light microscopy only, causing many taxa to be misidentified. Presently, electron microscopy is considered the appropriate tool for description of diplomonads. The existence of morphologically very similar genotypes/species has in addition prompted the need for molecular tools to resolve the true identity of many diplomonad taxa. To further explore the relationship within the Hexamitinae we have sequenced most of the SSU rRNA gene from Spironucleus torosa isolated from Atlantic cod, Spironucleus meleagridis isolated from turkey, Spironucleus vortens isolated from ide and Hexamita nelsoni isolated from oyster. Phylogenetic analyses recovered three non-monophyletic Spironucleus clades that may have originated separately in the sea, in freshwater or on land. Spironucleus torosa was identified as a sister taxon to Spironucleus barkhanus and Spironucleus salmonicida. Spironucleus vortens from ide appeared to be genetically very different from Spironucleus vortens isolated from angelfish.

Ultrastructure and molecular diagnosis of Spironucleus salmonis (Diplomonadida) from rainbow trout Oncorhynchus mykiss in Germany.

Diplomonad flagellates infect a wide range of fish hosts in aquaculture and in the wild in North America, Asia and Europe. Intestinal diplomonad infection in juvenile farmed trout can be associated with morbidity and mortality, and in Germany, diplomonads in trout are commonly reported, and yet are poorly characterised. We therefore undertook a comprehensive study of diplomonads from German rainbow trout Oncorhynchus mykiss, using scanning and transmission electron microscopy, and sequencing of the small subunit (ssu) rRNA gene. The diplomonad was identified as Spironucleus salmonis, formerly reported from Germany as Hexamita salmonis. Our new surface morphology studies showed that the cell surface was unadorned and a caudal projection was present. Transmission electron microscopy facilitated new observations of functional morphology, including vacuoles discharging from the body surface, and multi-lobed apices of the nuclei. We suggest the lobes form, via hydrostatic pressure on the nucleoplasm, in response to the beat of the anterior-medial flagella. The lobes serve to intertwine the nuclei, providing stability in the region of the cell exposed to internal mechanical stress. The ssu rRNA gene sequence clearly distinguished S. salmonis from S. barkhanus, S. salmonicida, and S. vortens from fish, and can be used for identification purposes. A 1405 bp sequence of the ssu rRNA gene from S. salmonis was obtained and included in a phylogenetic analysis of a selection of closely related diplomonads, showing that S. salmonis was recovered as sister taxon to S. vortens.

Gross and microscopic pathology associated with large cavernous lesions in muscle of Chinook salmon from Lake Ontario.

Since 1999, eight adult Chinook salmon (Onchorhynchus tshawytscha) from Lake Ontario with large, focal, cavernous, fluid-filled muscle lesions have been examined in our respective laboratories. Gross and microscopic examination, cytology, and bacteriology were performed. Microscopically the lesions were consistent with chronic abscesses. Cytologic evaluation revealed diplomonad flagellate Spironucleus within these lesions. We provide a description of the gross and microscopic pathology associated with the cavernous lesions.

Evidence from SSU rRNA phylogeny that Octomitus is a sister lineage to Giardia.

Octomitus intestinalis is a diplomonad flagellate inhabiting the digestive tract of rodents and amphibians. Octomitus is of evolutionary interest because, based on ultrastructural characteristics, it is thought to be closely related to the morphologically derived genus Giardia, and together they have been proposed to make up the Giardiinae. In molecular trees of diplomonads, Giardia is the deepest branching lineage, so identifying a sister group to Giardia that is less derived would be informative. Octomitus is a logical candidate for this position, but unfortunately there are no molecular data from it, and it is not available in culture. To determine the position of Octomitus, and specifically test whether it is more closely related to Giardia than other diplomonads, we have isolated it directly from the caecum of wild mice and characterized its small subunit ribosomal RNA (SSU rRNA) gene. Phylogenetic analysis showed Octomitus to be the sister to Giardia with strong support, together occupying one side of the deepest split in the diplomonad tree.

Genetic diversity of Diplomonadida in fish of the genus Coregonus from Southeastern Siberia.

Diplomonadida are primitive flagellate protozoa, among which both commensals and pathogens have been recorded. To date, members of the genera Hexamita and Spironucleus have been reported in the digestive system of fish in the Baikal region. We determined the genetic diversity of Diplomonadida in fish of the genus Coregonus from south-eastern Siberia using molecular-genetic methods. Fish for analysis were caught in Lake Baikal and in the Barguzin, Nepa, Chechuy, and Kirenga rivers from 2010 to 2013. Gall bladders, hindguts and foreguts of 120 specimens of Coregonus migratorius representing three morpho-ecological groups, 25 specimens of Coregonus lavaretus baicalensis, 25 specimens of Coregonus tugun and 30 specimens of Coregonus lavaretus pidschian were analysed via amplification with primers specifically designed for eukaryotes. Amplicons positive for Diplomonadida were sequenced. A phylogenetic analysis revealed that diplomonad flagellates of whitefish from Southeastern Siberia belong to Spironucleus barkhanus. Positive Diplomonadida DNA samples were analysed with primers designed in the present study for the amplification of small subunits of ribosomal DNA fragments of S. barkhanus (about 1,430 bp) and sequenced. Phylogenetic analysis revealed inside the clade of S. barkhanus besides the cosmopolitan genotype from European salmon that was detected earlier in Baikalian grayling, a new genotype unique to the fish of the genus Coregonus from Lake Baikal.

Spironucleus meleagridis, an enteric diplomonad protozoan of cockatiels (Nymphicus hollandicus): preliminary molecular characterization and association with clinical disease.

A flagellated enteric diplomonad protozoan consistent with Spironucleus meleagridis (formerly Hexamita meleagridis) associated with gastrointestinal disease and mortality in psittacine birds including cockatiels (Nymphicus hollandicus) has been sporadically described in the literature. However, molecular characterization of psittacine protozoal isolates had not yet been performed. The 16S rRNA gene from a protozoan persistently shed in the feces in a small group of cockatiels demonstrated a 98% molecular identity with S. meleagridis isolated from turkeys. Based on these sequence data, a diagnostic PCR assay was developed to detect the presence of S. meleagridis. Nineteen privately owned pet cockatiels from unrelated households were clinically evaluated. All birds microscopically positive for this organism were PCR positive, with several additional birds microscopically negative but PCR positive. Many of the birds identified as positive for S. meleagridis by fecal PCR had signs of gastrointestinal disease such as diarrhea, soft feces, and melena, whereas none of the birds that tested negative had gastrointestinal signs. Examination of feces from two unrelated cockatiel breeding facilities revealed 70% and 86% PCR positive rates. Prevalence of infection and incidence of clinical disease, including factors that lead to clinical manifestation such as viral, bacterial, or mycotic coinfections, are not yet known and warrant further study, but spironucleosis is likely an under-recognized disease in cockatiels.

Detection and quantification of Spironucleus barkhanus in experimentally infected Atlantic salmon Salmo salar.

The course of Spironucleus barkhanus (Diplomonadida: Hexamitidae) infection in Atlantic salmon Salmo salar L. (Salmonidae) has 2 distinct phases, a blood phase and a tissue phase. To detect and quantify an infection, 3 parasitological techniques, namely Wet Mount Examination (WME), Hematocrit Centrifuge Technique (HCT) and the Hemocytometer (HCM) were used. In addition, 1 immunological technique, enzyme-linked immunosorbent assay (ELISA), was developed to detect specific antibodies against S. barkhanus. This technique would be particularly useful for epidemiological studies where large numbers of fish had to be examined. It would also be a good technique to detect infection during the tissue phase of the disease when there were no or a low number of parasites in the blood.

Systemic spironucleosis in sea-farmed Atlantic salmon Salmo salar, caused by Spironucleus barkhanus transmitted from feral Arctic char Salvelinus alpinus?

A hexamitid flagellate was found in the gall bladder and intestine of Arctic char Salvelinus alpinus in northern Norway. Scanning and transmission electron microscopy showed this flagellate to be identical to Spironucleus barkhanus from grayling Thymallus thymallus and farmed Atlantic salmon Salmo salar. It is hypothesized that systemic spironucleosis in sea-caged Atlantic salmon was due to transmission of flagellates from feral char to the salmon.

Spironucleosis in Australian king parrots (Alisterus scapularis).

OBJECTIVE: To describe a syndrome of wasting, diarrhoea and mortality in Australian king parrots (Alisterus scapularis). DESIGN: Field observations and laboratory examinations. Procedure Pathological examinations were performed on 50 Australian king parrots with wasting and diarrhoea. Wet preparations of intestinal contents were examined by light microscopy. Tannins were extracted from acorns (Quercus sp) and tested for toxicity in mice. CLINICAL SIGNS AND EPIDEMIOLOGY: A syndrome of wasting, diarrhoea and mortality was observed in wild juvenile Australian king parrots in eastern Australia from 1984 to 2000. Sporadic cases and outbreaks of disease occurred from May to September in New South Wales, the Australian Capital Territory and Victoria. Outbreaks in the Australian Capital Territory in 1990 and 1991 were associated with parrots congregating to feed on acorns. Most affected birds failed to respond to treatment with dimetridazole and died 1 to 14 days after hospitalisation. Selected cases recovered following treatment with metronidazole. PATHOLOGY: Affected birds were emaciated, with faecal matting of feathers around the cloaca and yellow-green fluid, foamy intestinal contents. Abundant motile Spironucleus trophozoites were observed in wet preparations of faeces of clinically affected birds and intestinal contents of birds examined within 1 h of death. Protozoa were detected histologically in crypts of Lieberkühn in the intestine in association with exudation of mucus (catarrhal enteritis) or lymphoplasmacytic enteritis. Toxicology Tannin extracts from acorns induced periacinar hepatic necrosis in mice. CONCLUSION: Wasting, diarrhoea and mortality in wild juvenile Australian king parrots were associated with Spironucleus-like protozoa in the intestine. Acorns were not considered to be the cause of the syndrome.

Development of a PCR assay for the detection of Spironucleus muris.

Spironucleus muris is a protozoan that can colonize the intestinal tract of many rodent species. Although its effects on animal health and research are debated, S. muris is often included on exclusion lists for rodent facilities. Common diagnostic tests for S. muris are insensitive and typically are performed at postmortem examination. We sought to develop a PCR-based diagnostic test with sufficient sensitivity and specificity for use on fecal samples from live rodents. We designed and optimized a PCR assay that targeted the 16S-like rRNA gene of S. muris. The assay was highly specific, given that samples from mice contaminated with S. muris were PCR positive, whereas samples from mice contaminated with other protozoa were negative. The assay also was highly sensitive, detecting as few as 5 template copies per microliter diluent. All mice positive for S. muris on postmortem exams also were positive by fecal PCR. Moreover, S. muris was detected by PCR in mice negative by postmortem examination but from colonies known to be contaminated as well as in rats and hamsters. To assess protozoal loads in mice of differing ages, the PCR assay was adapted to a quantitative format. Fecal loads of S. muris were highest in 4-wk-old mice and declined with age. The PCR assay developed promises to be a highly specific antemortem diagnostic assay with higher sensitivity than that of existing postmortem tests.

Multigene phylogenies of diverse Carpediemonas-like organisms identify the closest relatives of 'amitochondriate' diplomonads and retortamonads.

Diplomonads, retortamonads, and "Carpediemonas-like" organisms (CLOs) are a monophyletic group of protists that are microaerophilic/anaerobic and lack typical mitochondria. Most diplomonads and retortamonads are parasites, and the pathogen Giardia intestinalis is known to possess reduced mitochondrion-related organelles (mitosomes) that do not synthesize ATP. By contrast, free-living CLOs have larger organelles that superficially resemble some hydrogenosomes, organelles that in other protists are known to synthesize ATP anaerobically. This group represents an excellent system for studying the evolution of parasitism and anaerobic, mitochondrion-related organelles. Understanding these evolutionary transitions requires a well-resolved phylogeny of diplomonads, retortamonads and CLOs. Unfortunately, until now the deep relationships amongst these taxa were unresolved due to limited data for almost all of the CLO lineages. To address this, we assembled a dataset of up to six protein-coding genes that includes representatives from all six CLO lineages, and complements existing rRNA datasets. Multigene phylogenetic analyses place CLOs as well as the retortamonad Chilomastix as a paraphyletic basal assemblage to the lineage comprising diplomonads and the retortamonad Retortamonas. In particular, the CLO Dysnectes was shown to be the closest relative of the diplomonads + Retortamonas clade, with strong support. This phylogeny is consistent with a drastic degeneration of mitochondrion-related organelles during the evolution from a free-living organism resembling extant CLOs to a probable parasite/commensal common ancestor of diplomonads and Retortamonas.

Suboptimal ability of dirty-bedding sentinels to detect Spironucleus muris in a colony of mice with genetic manipulations of the adaptive immune system.

Spironucleus muris is an unacceptable infectious agent for most rodent colonies. Exposure of sentinel mice to dirty bedding and examination of sentinel intestinal smears was not sufficient for identification of the extent of spironucleosis within 1 mouse room. Clinical abnormalities were not reported in the animals housed in the room despite extensive breeding and a preponderance of mice genetically engineered to have nonfunctional T and B cells. In addition, researchers reported that the infection had not altered their research data. During investigation of the outbreak, direct intestinal smears performed on related animals (conspecifics, offspring, or siblings) revealed that immunodeficient mice often tested negative whereas the immunocompetent cohort tested positive. In this study, we used culled colony animals and compared direct intestinal exam test results with histologic results. The comparison showed the extent of false negatives that may occur when direct intestinal exam alone is used to detect this protozoon. Sensitivity of the direct intestinal exam for detection of S. muris was calculated to be 71%, while histology sensitivity was 91%. In light of the study results and an extensive literature review, we revised our health surveillance plan so that the age and duration of exposure to dirty bedding among sentinel mice is varied at the time of testing.

Detection of Spironucleus muris in unpreserved mouse tissue and fecal samples by using a PCR assay.

The purpose of this study was to develop a rapid DNA isolation method and a sensitive and specific PCR assay for detecting Spironucleus muris in mouse tissue and fecal samples. A PCR assay based on the carboxy terminus of the elongation factor 1a gene was developed; the PCR product was confirmed by nucleic acid sequencing and nested PCR. The new PCR assay then was used to test feces from animals that had been screened for S. muris by using direct intestinal examination and histology. The PCR assay was determined to be a more sensitive test than either direct intestinal examination or intestinal histology. To our knowledge, this assay represents the first use of a PCR-based diagnostic screening method to confirm the presence of S. muris in murine tissue and fecal samples.