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At least 19 recordsLinked to original sources
PubMed1998

In vitro susceptibilities of the microsporidia Encephalitozoon cuniculi, Encephalitozoon hellem, and Encephalitozoon intestinalis to albendazole and its sulfoxide and sulfone metabolites.

In vitro comparisons demonstrated that the efficacy of albendazole, albendazole-sulfoxide, and albendazole-sulfone against pathogenic Encephalitozoon species was proportional to the degree of oxidation at a concentration of >10(-3) microgram/ml. Furthermore, at a concentration of <10(-2) microgram/ml, benzimidazoles were more effective against Encephalitozoon cuniculi and Encephalitozoon hellem than against Encephalitozoon intestinalis.

Albendazole↗
PubMed2002

Characterization of aminopeptidase activity from three species of microsporidia: Encephalitozoon cuniculi, Encephalitozoon hellem, and Vittaforma corneae.

Microsporidia are obligate intracellular parasites of the phylum Microspora. To date, more than 1,200 species within 144 genera have been described, with 14 infecting humans. Currently, no effective treatment exists for human microsporidiosis. In this study, the biochemical properties of the aminopeptidases were investigated within several species of microsporidia. Aminopeptidase activity was detected in 3 species of microsporidia, Encephalitozoon cuniculi, E. hellem, and Vittaforma corneae, using a fluorometric substrate assay. Each species exhibited distinct aminopeptidase properties. The cytosolic neutral aminopeptidase activities of the Encephalitozoon spp. were characterized as preferentially cleaving leucine, whereas those of V. corneae cleaved arginine. Native polyacrylamide gel electrophoresis estimated the molecular mass of E. cuniculi, E. hellem, and V. corneae as 74, 72, and 79 kDa, respectively. Enzymatic activity was inhibited by bestatin and it's analogue, nitrobestatin, indicating that the enzyme was an aminopeptidase for all species. Inhibition with the chelating agents ethylenediaminetetraacetic acid and 1,10phenanthroline characterized the enzymes as metalloaminopeptidases. Subcellular fractionation of the 3 microsporidial species suggested that the enzyme activity was localized in the cytosolic fraction. Optimal enzyme activity was observed at pH 7.2 for all species. This is the first report of enzyme characterization from these 3 species of microsporidia.

Aminopeptidases↗
PubMed2002

[Encephalitozoon cuniculi and Encephalitozoon intestinalis--causes of opportunistic infections].

Microsporidia (phylum Microsporidia) are intracellular parasites that infect a wide range of protozoa, invertebrates and vertebrate hosts. Over a 1000 species have been classified into approximately 100 genera. Historically, microsporidial infections in silkworms, honey bees, and salmonid fish have been responsible for significant economic losses. More recently, microsporidiosis has been recognized as an important opportunistic infection in immunologically compromised patients. In this review there is information on the immunobiology of microsporidia Encephalitozoon cuniculi and Encephalitozoon intestinalis which were identified as the most common causative agents of microsporidiosis in mammals. Most of what is known about the immunology of microsporidiosis is based on experiments with the microsporidian Encephalitozoon cuniculi.

Animals↗
PubMed2005

Activity of bleach, ethanol and two commercial disinfectants against spores of Encephalitozoon cuniculi.

Encephalitozoon cuniculi is a small protist parasite in the phylum Microspora. Hosts are infected by ingestion or inhalation of spores passed in the urine or feces. Infection with E. cuniculi is usually asymptomatic, except in young or immunocompromised hosts. This study examined the effects of various disinfectants on in vitro infectivity of E. cuniculi spores. Spores of E. cuniculi were exposed to several dilutions of commercial bleach, 70% ethanol and dilutions of commercial disinfectants HiTor and Roccal for 10 min and then loaded onto human fibroblast cells (Hs68 cells). Ten minutes of exposure to these disinfectants was lethal to E. cuniculi spores. Additional exposure time studies were done using dilutions of bleach at 0.1, 1 and 10%, and 70% ethanol. Exposure of E. cuniculi spores to 1 or 10% bleach for 30s rendered them non-infectious for Hs68 cells. Growth of E. cuniculi was observed in Hs68 cells inoculated with spores treated with 0.1% bleach for 30s or 1, 3 and 5 min, but not with spores treated for 7 min or longer. Exposure of E. cuniculi spores to 70% ethanol for 30s rendered them non-infectious for Hs68 cells. Spores of E. cuniculi are more sensitive to disinfectants than are coccidial oocysts and other parasite cysts. The relatively short contact time needed to kill spores indicates that disinfection of animal housing may be a viable means to reduce exposure of animals to E. cuniculi spores.

Animals↗
PubMed2005

A cytosine-rich region upstream of start codons serving as a signal for initiation of translation in Encephalitozoon cuniculi?

Encephalitozoon cuniculi, an intracellular eukaryote frequently infecting immunodeficient humans, displays pronounced compaction in its genes. Short-leaded mRNA has been observed which has led to speculation into alternative mechanisms of translation initiation. It has been proposed that a 'downstream box' could serve as an initiation signal. In this report, non-randomness analysis was used to study the genes of E. cuniculi. Surprisingly, it was found that the region 5-10nt upstream of start codons is highly cytosine-enriched and this phenomenon clearly differentiates genes of predicted high and low expressivity. These two groups of genes can, on the other hand, not be clearly differentiated from non-randomness plots downstream of their start codons. The data thus do not support the 'downstream box' hypothesis but seem to suggest that initiation is depending on the region immediately upstream of start codons. The cytosine richness has no known parallel in other eukaryotes, prokaryotes or archaebacteria.

Animals↗
PubMed2005

Direct agglutination test for Encephalitozoon cuniculi.

Encephalitozoon cuniculi is a small protozoan parasite in the phylum Microspora. It has been shown to naturally infect several host species, including humans. Infection with microsporidia is usually asymptomatic, except in young or immunocompromised hosts. Currently, serological diagnosis of infection is made using the indirect immunofluorescent antibody assay (IFA) or enzyme-linked immunosorbent assay (ELISA). Although these methods are sensitive and reliable, there are several drawbacks to the IFA and ELISA tests. Cross-reactivity between other Encephalitozoon species is common, and specialized equipment is required to conduct these tests. This paper reports the development of a direct agglutination test for detecting IgG antibodies to E. cuniculi. The utility of the agglutination test was examined in CD-1 and C3H/He mice infected with E. cuniculi or one of 2 other Encephalitozoon species. Test sera were incubated overnight with eosin-stained microsporidia spores in round-bottom microtiter plates. In positive samples, agglutination of spores with antibodies in test sera resulted in an opaque mat spread across the well. The results indicate that the agglutination test is 86% sensitive and 98% specific for E. cuniculi, with limited cross-reactivity to Encephalitozoon intestinalis. No cross-reactivity to Encephalitozoon hellem was observed. The test is fast and easy to conduct, and species-specific antibodies are not required.

Agglutination Tests↗
PubMed1980

Effect of fumagillin on in vitro multiplication of Encephalitozoon cuniculi.

Encephalitozoon cuniculi (Levaditi, Nicolau & Schoen) is an obligate intracellular pathogenic parasite of rabbits, carnivores, laboratory rodents, and a variety of other mammals. Cell cultures of rabbit and canine cells were infected with rabbit and dog isolates of E. cuniculi. Four days later 5 microgram/ml of fumagillin was introduced into the culture medium. The multiplication of the parasite was inhibited within 48 h and this effect was maintained as long as the antibiotic remained in the medium. There was no effect when spores and proliferative forms of the parasite were incubated with fumagillin before being used for infecting host cells. No infection occurred, however, if the antibiotic was added to the culture medium before introduction of E. cuniculi. On electron-microscopic examination, the treated parasites were found to have severe cytoplasmic swelling, vesicular distortion of the plasma membrane, and marked reduction in cytoplasmic ribosomes. it was concluded that fumagillin blocks multipliation of E. cuniculi in vitro. The drug may be useful for the treatment or prevention of spontaneous encephalitozoonosis.

Animals↗
PubMed1979

The biology of Encephalitozoon cuniculi.

Encephalitozoon cuniculi is a widespread and often sub-clinical microsporidian parasite of homeothermic animals, including man. The biology, pathology and taxonomy of the organism is reviewed and the available diagnostic methods discussed. Transmission is almost invariably via the oral route either by ingestion of contaminated tissues and other foods or by ingestion of infected urine, perhaps on food, or when animals lick the coats of others. Transplacental transmission does not seem common but can probably occur when susceptible animals are infected during pregnancy. It has been demonstrated once in mice and once in rabbits. The possibility of arthropod vector transmission awaits thorough investigation but this is unlikely to be as important as the oral route. No drugs have yet been found to be effective against E. cuniculi but control of the spread of encephalitozoonosis in laboratory animals, at least, can probably be achieved by maintaining laboratory hygiene.

Animals↗
PubMed1993

Detection of microsporidian spores in clinical samples by indirect fluorescent-antibody assay using whole-cell antisera to Encephalitozoon cuniculi and Encephalitozoon hellem.

Three polyclonal mouse antisera, to Encephalitozoon cuniculi, Nosema algerae, and Nosema corneum, and two polyclonal rabbit antisera, to E. cuniculi and Encephalitozoon hellem, were used in an indirect fluorescent-antibody assay (IFA) with Enterocytozoon bieneusi, E. cuniculi, and Encephalitgozoon. hellem spores (spores of the last two were taken from culture). Enterocytozoon bieneusi cannot be cultured. By IFA, antisera to E. cuniculi and E. hellem reacted strongly and equally with each other's spores. The mouse antisera reacted strongly with the homologous species, but for these there was segmental and particulate or "dot" staining of heterologous microsporidian spores, indicating cross-reactions with more selected antigens. In fecal samples, cross-reactions with both mouse and rabbit antisera were sometimes seen with different yeast species, with species of streptococci, and species of gram-negative rods. There were no cross-reactions to staphylococci. Enterocytozoon bieneusi was easily identified in duodenal and colonic biopsies, duodenal and colonic fluids, and feces of symptomatic AIDS patients by IFA. In a study of 12 AIDS patients with diarrhea, the new IFA identified microsporidia in all of 11 fecal samples, three colon fluids, six duodenal fluids, and three duodenal biopsy touch preparations. Although the fecal sample of 1 of the 12 was negative, the patient's duodenal fluid contained microsporidian spores by IFA.

Animals↗
PubMed1978

Some factors influencing the in vitro infectivity and replication of Encephalitozoon cuniculi.

Rabbit Encephalitozoon cuniculi were propagated in vitro using rabbit choroid plexus (RCP) cells. The organisms reached maximum titer and numbers by 15 days. The source and in vitro passage level of RCP cells moderately influenced the sensitivity of the cells to infection. Cells less than 1 week old were significantly less sensitive than older cells. A moderate increase in infectivity for RCP cells was demonstrated with increasing organism passage level in vitro. Rabbit E. cuniculi were not affected by penicillin-streptomycin or gentamicin in the culture medium. The organism survived more than 9 days in buffer at 37 C and least 24 days at 4 and 20 C. Storage at -70 C or in liquid nitrogen was successful for at least 6 months. Encephalitozoon cuniculi survived 60 but not 120 min at 56 C. They were killed after 10 min of autoclaving and by 2% (v/v) Lysol, 10% (v/v) formalin and 70% (v/v) ethyl alcohol. The organisms survived at least 24 h at pH 9 or pH 4 and were not affected by sonication, freezing and thawing, or distilled water but lost significant infectivity after 24 h in CsCl or 40% (w/v) sucrose.

Animals↗
PubMed2003

Humoral immune response in adult blue foxes (Alopex lagopus) after oral infection with Encephalitozoon cuniculi spores.

Encephalitozoon cuniculi causes severe diseases in blue fox puppies. When pregnant vixens are infected, parasites are transmitted over the placenta to the unborn that subsequently develop encephalitozoonosis. Adult foxes themselves do not have signs of disease, but show antibody titres to E. cuniculi. The purpose of the present study was to gain information on the immune response in adult foxes after experimental infection. Sixteen foxes were infected orally with E. cuniculi spores, eight of them twice and 28 days apart. The two groups of animals showed elevated serological values in both the carbon immunoassay and in the ELISA. Elevated serological levels were recorded up to 1 year after the infection took place. The control group (n=8) remained serologically negative throughout the trial. The results of the study showed that blue foxes could be seropositive for at least a year after oral infection with E. cuniculi.

Animals↗
PubMed1999

CD8+ CTLs are essential for protective immunity against Encephalitozoon cuniculi infection.

Encephalitozoon cuniculi is a protozoan parasite that has been implicated recently as a cause of opportunistic infection in immunocompromised individuals. Protective immunity in the normal host is T cell-dependent. In the present study, the role of individual T cell subtypes in immunity against this parasite has been studied using gene knockout mice. Whereas CD4-/- animals resolved the infection, mice lacking CD8+ T cells or perforin gene succumbed to parasite challenge. The data obtained in these studies suggest that E. cuniculi infection induces a strong and early CD8+ T response that is important for host protection. The CD8+ T cell-mediated protection depends upon the CTL activity of this cell subset, as the host is rendered susceptible to infection in the absence of this function. This is the first report in which a strong dependence upon the cytolytic activity of host CD8+ T cells has been shown to be important in a parasite infection.

Animals↗
PubMed2004

Induction of a rapid and strong antigen-specific intraepithelial lymphocyte response during oral Encephalitozoon cuniculi infection.

Encephalitozoon cuniculi continues to pose a problem for immunocompromised patients. Previous studies from our laboratory have elucidated the importance of the CD8(+) T cell subset in the protection against systemic parasite infection. There have been no studies related to the mucosal immunity induced against this orally acquired pathogen. In the present study, the immune response generated in the gut after oral E. cuniculi infection was evaluated. An early and rapid increase of the intraepithelial lymphocyte (IEL) population of orally infected animals was observed. This increase in the IEL population started as early as day 3 and peaked at day 7 postinfection with persistent elevation thereafter. At day 7 postinfection, IELs expressed strong cytokine messages (IFN-gamma and IL-10) and were highly cytotoxic for parasite-infected syngeneic macrophages. At an E:T ratio of 80:1, these cells were able to cause >60% Ag-specific target cell lysis. A significant increase in the CD8alphaalpha subset of IEL in response to an oral E. cuniculi infection was observed. To the best of our knowledge, such an early expansion of an IEL population exhibiting strong ex vivo cytotoxicity has not been reported with infectious models. These data suggest that IELs act as important barriers for multiplication of this organism leading to the successful resolution of infection. The protective role of IELs may be due both to their inflammatory (IFN-gamma production and cytotoxic response) as well as immunoregulatory (IL-10 production) properties.

Administration, Oral↗
PubMed1999

Molecular karyotype diversity in the microsporidian Encephalitozoon cuniculi.

The microsporidian Encephalitozoon cuniculi can infect numerous mammals, including man. Three strains of E. cuniculi have been identified so far, the major marker being the number of a tetranucleotide repeats in the rDNA internal transcribed spacer. We investigated diversity at the chromosomal level through the electrophoretic karyotypes obtained from 15 E. cuniculi isolates from 5 different host species. All preparations provided patterns with 9-12 bands within a narrow molecular size range. Six karyotype forms were distinguished, involving subdivision of strain I into 3 types (A, B, C) and strain II into 2 types (D, E). The types A, B and C were mainly associated with isolates from rabbits of different geographical origins. The types D, E and F were characterized by a reduced chromosome size range, 2 of these appearing specific to a carnivorous host species (D in dog and F in blue fox). Hybridization experiments showed that all E. cuniculi isolates possess 11 chromosomes, with a size polymorphism entailing occasional electrophoretic comigration of heterologous chromosomes and differential migration of homologous ones. DNA rearrangements should occur during mitosis and the hypothesis of diploidy for the basic state of E. cuniculi seems likely.

Animals↗
PubMed1998

On proteins of the microsporidian invasive apparatus: complete sequence of a polar tube protein of Encephalitozoon cuniculi.

The microsporidian Encephalitozoon cuniculi is an obligate intracellular parasite that can cause opportunistic infections in AIDS patients. Spore invasion of host cells involves extrusion of a polar tube. After immunocytochemical identification of several polar tube proteins (PTPs) in E. cuniculi, a major PTP was isolated from two-dimensional gels and two peptide fragments were sequenced. The complete nucleotide sequence of the corresponding gene was obtained using a combination of PCR amplification and cloning techniques. The gene exists as a single copy per haploid genome and encodes an acidic proline-rich protein, with a deduced molecular mass of 37 kDa, that contains four tandemly arranged 26-amino-acid repeats. An N-terminal region of 22 residues represents a cleaved signal peptide, probably involved in the targeting of the PTP. No similarity with known proteins has been found. The protein was expressed in Escherichia coli, purified and injected into mice. The antisera reacted specifically with the polar tube in indirect immunofluorescence assays and electron microscope immunocytochemistry. Further identification of conserved and variable PTP structural motifs should be useful for diagnostic purposes and new therapeutic strategies.

Amino Acid Sequence↗
PubMed1979

A simple method for the detection of antibodies to Encephalitozoon cuniculi in rabbits.

Rabbit antibodies against Encephalitozoon cuniculi were detected in an indirect microagglutination test using a bead substrate to which anti-rabbit immunoglobin G light and heavy chain antibodies were coupled. The test was positive using immune whole serum or F(ab)' and F(ab)'2 fragments of immunoglobin G but negative using the F(c) fragment. The reaction was blocked by saturating the beads with rabbit serum or by absorbing positive sera with excess Encephalitozoon cuniculi. The test provided a simple method to detect antibodies to Encephalitozoon cuniculi, did not require elaborate equipment and could be performed using frozen antigen.

Agglutination Tests↗
PubMed2000

Phagocytic uptake of Encephalitozoon cuniculi by nonprofessional phagocytes.

Encephalitozoon cuniculi is an obligate intracellular, spore-forming parasite belonging to the microsporidia that can cause disseminated infection in immunocompromised persons. E. cuniculi spores infect host cells by germination, i.e., by explosively everting the polar filament, through which the spore contents (sporoplasms) are subsequently injected into the cytoplasm. In addition, we observed intracellular, nongerminated spores in various nonprofessional phagocytes. In MRC5 cells, the number of internalized spores was approximately 10-fold higher than the number of injected sporoplasms. Compared to the rate of uptake by human monocyte-derived macrophages, internalization rates by A549 cells, MRC5 cells, and 293 cells were 0.6, 4.4, and 22.2%, respectively. The mechanism of uptake was studied in MRC5 cells. Killed spores were internalized at the same rate as live spores, indicating that nongerminated parasites do not actively participate in cell entry. Cytochalasin D inhibited uptake of spores by 95%, demonstrating an actin-dependent process. By electron and epifluorescence microscopy, intracellular spores were found in a tightly fitting membrane-bound compartment. The vacuole containing the spores was positive for the lysosomal membrane protein LAMP-1 and colocalized with the late endosomal-lysosomal content marker rhodamine dextran. Our results show that, in addition to the unique way in which microsporidia infect cells, E. cuniculi spores enter nonprofessional phagocytes by phagocytosis and traffic into a late endosomal-lysosomal compartment.

Actins↗