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PubMed1996

Immunologic and molecular characteristics of Encephalitozoon-like microsporidia isolated from humans and rabbits indicate that Encephalitozoon cuniculi is a zoonotic parasite.

To assess the zoonotic potential of Encephalitozoon-like microsporidia, we isolated and cultivated spores from specimens of urine, respiratory secretions, and stool from six patients infected with human immunodeficiency virus and from nine rabbits. Because spores of Encephalitozoon-like species are indistinguishable by microscopy, we characterized the isolates by western blot analysis and by restriction enzyme analysis of the small subunit (SSU) rDNA after amplification by the polymerase chain reaction. We identified Septata intestinalis in one patient and Encephalitozoon hellem in two symptomatic patients. Encephalitozoon cuniculi was found in all rabbits and in three patients. One of these patients had clinical manifestations of infection with this parasite (severe interstitial pneumonitis). We observed abatement of symptoms and cessation of parasite excretion when these patients were treated with albendazole. Our findings suggest that E. cuniculi may be pathogenic in humans and that it is a zoonotic parasite.

AIDS-Related Opportunistic Infections↗
PubMed1989

Prevalence of antibodies to Encephalitozoon cuniculi in stray dogs as determined by an ELISA.

An ELISA, using Encephalitozoon cuniculi spores as antigen, was used to determine the prevalence of specific anti-E cuniculi IgG in a group of stray dogs. In a preliminary survey 51 of 248 sera were classified as positive with titres of 1:400 to 1:3200. The 18 sera with titres of 1:400 were reclassified as negative when no IgG binding to the spores could be detected by comparison with a standard curve of anti-E cuniculi IgG. The remaining 33 sera (13.3 per cent) were classified as low, moderate or strong positives. Comparison of total IgG and specific IgG showed that specific IgG was greatly increased in the moderately and strongly positive sera. E cuniculi may be of importance as one cause of fading puppy syndrome when transmitted transplacentally, and as a complicating infection in human immunodeficiency diseases.

Animals↗
PubMed1979

Simple focus assay for Encephalitozoon cuniculi.

In this is vitro infectivity assay for Encephalitozoon cuniculi, lesions due to the organism appeared as macroscopically distinct foci. The number of such foci was used as a direct measure of the number of infectious units in the original sample. The expected correlation between focus-forming units and 50% infectious doses was observed in limit dilution experiments.

Cell Line↗
PubMed2002

An indirect ELISA for detection of Encephalitozoon cuniculi infection in farmed blue foxes (Alopex lagopus).

Infection with the intracellular microsporidium Encephalitozoon cuniculi can cause serious disease, encephalitozoonosis, in the blue fox (Alopex lagopus). The disease diagnosis is based on clinical signs and pathological findings, and detection of E. cuniculi or circulating antibodies directed against the parasite. Indirect immunofluorescence (IFAT) and carbon immunoassay (CIA) are the most commonly used serological methods for diagnosis in this species. In the present study, an indirect ELISA (enzyme linked immunosorbent assay) was established and evaluated against IFAT by testing of 205 field samples from blue foxes. There was high agreement between the results of the ELISA and CIA (kappa=0.99), and the ELISA and IFAT (kappa=0.958). There was no significant statistical difference between the tests (p>0.05). It was concluded that the ELISA could be used to identify seropositive farmed blue foxes. The advantage of the ELISA lies in the potential of screening large numbers of animals with the goal of eradicating E. cuniculi infection in the farms.

Animals↗
PubMed1993

Prevalence of Encephalitozoon cuniculi antibodies in terrestrial mammals in Iceland, 1986 to 1989.

Antibodies to Encephalitozoon cuniculi were found in wild arctic foxes (Alopex lagopus), feral mink (Mustela vison), wood mice (Apodemus sylvaticus) and house mice (Mus musculus) in Iceland. Animals with antibodies were found throughout the country. No lesions attributable to encephalitozoonosis were found in adult animals necropsied. However, one arctic fox cub with a neurological disorder had pathological and serological evidence of encephalitozoonosis.

Animals↗
PubMed2002

First isolation and characterisation of Encephalitozoon cuniculi from a free-ranging rat (Rattus norvegicus).

The microsporidian species Encephalitozoon cuniculi can infect a wide variety of mammals including man. It is a common parasite in rabbits and several sporadic infections in laboratory rats have been described. Based on molecular data three E. cuniculi strains have been identified. Here we describe the first in vitro propagation of E. cuniculi, which was isolated from a free-ranging rat (Rattus norvegicus). The rat was one of three seropositive animals among 23 rats captured in the city of Zurich. The new isolate was further characterised as strain II ("mouse"-strain) based on the rDNA internal transcribed spacer sequence. Western blot analysis of this isolate revealed slight differences to other available strain II isolates originating from laboratory mice and farmed blue foxes. The new isolate caused disseminated infection in liver and lung upon oral inoculation of Brown Norway (BN) rats and was transmitted to sentinel rats. This rat-adapted isolate will be valuable to study the pathogenesis of Encephalitozoon infections in the rat model.

Animals↗
PubMed1988

Dot enzyme-linked immunosorbent assay (dot ELISA) for antibodies to Encephalitozoon cuniculi.

A dot-ELISA procedure was developed to detect antibodies against Encephalitozoon cuniculi. Sera from 84 rabbits, 22 dogs, 18 squirrel monkeys and 200 mice were tested by dot-ELISA and most also were tested by immunofluorescence. Comparison of the two tests showed that there was excellent agreement of the results (Kappa values greater than or equal to 0.74) in all four species. Dot-ELISA is a simple, quantitative, rapid alternative to immunofluorescence when large numbers of serum samples must be evaluated.

Animals↗
PubMed1985

Susceptibility of cats, sheep, and swine to a rabbit isolate of Encephalitozoon cuniculi.

Newborn cats, pigs, and sheep (3 to 14 days old) and postweanling cats (2.5 months old) that had been inoculated with Gardner feline sarcoma virus and feline leukemia virus at 10 days of age were infected experimentally with a rabbit isolate of the mammalian protozoan parasite Encephalitozoon cuniculi. Infection occurred in all cats and in some sheep, but was questionable in pigs. Brain and kidney were the 2 major target organs in cats. The lesions were compatible with, but less severe than, those of naturally infected cats and other carnivores. Of 13 cats, E cuniculi could be detected morphologically in the kidneys of 12 cats and in the brain of 1 cat. The organisms were reisolated from 2 cats with ground tissue suspension of kidney or urine sediment. The indirect immunofluorescence antibody (IFA) titers were 1:20 to 1:1,280 at the time the animals were killed, but antibodies were not detected before inoculation. Lesions were seen in the kidneys of 2 of 4 sheep. These lesions were mild, but were compatible with those in a spontaneously affected goat. Encephalitozoon cuniculi were found morphologically in the kidney of 1 sheep with lesions. All sheep had IFA titers of 1:10 to 1:20 before inoculation, and the titers were 1:20 to 1:320 when they were killed. Vasculitis, similar to the subacute-to-chronic stage of polyarteritis nodosa, was observed in 1 of 8 pigs. The lesions were primarily present in the kidney; comparable but milder lesions were also seen in the heart and brain. Antibody was not detected before inoculation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Polyamine synthesis and interconversion by the Microsporidian Encephalitozoon cuniculi.

Polyamines are small cationic molecules necessary for growth and differentiation in all cells. Although mammalian cells have been studied extensively, particularly as targets of polyamine antagonists, i.e. antitumor agents, polyamine metabolism has also been studied as a potential drug target in microorganisms. Since little is known concerning polyamine metabolism in the microsporidia, we investigated it in Encephalitozoon cuniculi, a microspordian associated with disseminated infections in humans. Organisms were grown in RK-13 cells and harvested using Percoll gradients. Electron microscopy indicated that the fractions banding at 1.051-1.059/g/ml in a microgradient procedure, and 1.102-1.119/g/ml in a scaled-up procedure were nearly homogenous, consisting of pre-emergent (immature) spores which showed large arrays of ribosomes near polar filament coils. Intact purified pre-emergent spores incubated with [1H] ornithine and methionine synthesized putrescine, spermidine, and spermine, while [14C]spermine was converted to spermidine and putrescine. Polyamine production from ornithine was inhibitable by DL-alpha-difluoromethylornithine (DFMO) but not by DL-alpha-difluoromethylarginine (DFMA). Cell-free extracts from mature spores released into the growth media had ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (AdoMetdc), and spermidine/spermine N1-acetyltransferase (SSAT) activities. ODC activity was inhibited by DFMO, but not by DFMA. AdoMetdc was putrescine-stimulated and inhibited by methylglyoxal-bis(guanylhydrazone); arginine decarboxylase activity could not be detected. It is apparent from these studies that Encephalitozoon cuniculi pre-emergent spores have a eukaryotic-type polyamine biosynthetic pathway and can interconvert exogenous polyamines. Pre-emergent spores were metabolically active with respect to polyamine synthesis and interconversion, while intact mature spores harvested from culture supernatants had little metabolic activity.

Acetyltransferases↗
PubMed1980

A survey of serum antibodies to Encephalitozoon cuniculi in breeding rabbits and their young.

Screening of a rabbit breeding colony by the India-ink immunoreaction test revealed that 73% of the animals had antibodies to Encephalitozoon cuniculi. The study also indicated the passive transmission of antibodies from infected dams to their offspring. Ninety-five percent of the rabbits born to seropositive dams had maternal antibodies to Encephalitozoon cuniculi up to the age of 4 weeks with titers ranging from 1:25 to 1:800. After elimination of maternally transferred antibodies, about 50% of the young rabbits seroconverted; and from the age of 8--10 weeks, serum antibody titers over 1:800 were detectable. When these animals were tested again at 14 weeks, most of them had titers of 1:1600 or higher.

Animals↗
PubMed2004

Serodiagnostic studies in an immunocompetent individual infected with Encephalitozoon cuniculi.

Little is known about the prevalence and clinical significance of infection with Encephalitozoon species in immunocompetent individuals. In the present study, by using indirect immunofluorescence technique (IFAT), Western blot, and recombinant antigens of the spore wall (SWP1) and polar tube (PTP1, PTP2, and PTP3 ), we analyzed the IgG antibody response of a laboratory worker who was infected with Encephalitozoon cuniculi. Serum samples were analyzed 1, 20, 32, and 38 months after infection. After 1 month, by use of IFAT, only spore-wall antigens were recognized, an antibody reaction that changed toward both the spore wall and polar tube in the following months. By use of Western blot analysis, a characteristic pattern that recognized multiple bands was noticed. Reaction against SWP1 was present in all 4 serum samples. The IgG response against PTP1, PTP2, and PTP3 was not detectable 1 month after infection, but became evident in the follow-up serum samples. Serum samples showed cross-reactivity with the spore wall of Encephalitozoon hellem and Encephalitozoon intestinalis, but only little cross-reactivity with the polar tube of these parasites. This is the first study to our knowledge that provides full details about the antibody response against a specified Encephalitozoon species in an immunocompetent person. The results strongly encourage the development and use of reliable serodiagnostic methods, which will provide information about the prevalence and clinical significance of Encephalitozoon species infection in humans.

Animals↗
PubMedDate not supplied

Nucleotide sequences of DNA fragments of Encephalitozoon cuniculi amplified by polymerase chain reaction with primers regarded as specific for Echinococcus.

Encephalitozoon-like spores were separated from a human echinococcal liver lesion, which was caused by Echinococcus multilocularis. They were found to fall into the species Encephalitozoon cuniculi, which was shown to have En. cuniculi-specific DNA by way of polymerase chain reaction (PCR). We also used PCR to genetically discriminate between the En. cuniculi spores and the Ec. multilocularis larvae. Two primer sets, known to be specific for Echinococcus, were examined. These primers were expected to work normally when the two quite different DNA preparations were tested as templates, i.e. only Echinococcus DNA could give a positive signal in the PCR tests. However, it was found that the two Echinococcus-specific primer sets could amplify not only Ec. multilocularis DNA, but also En. cuniculi spore DNA. We then tried to determine the order of nucleotides in the Echinococcus-specific primers-amplified En. cuniculi PCR products and compared the determined sequences with those of Ec. multilocularis. The results clearly indicated that sequencing made little difference between En. cuniculi and Ec. multilocularis.

Animals↗
PubMed1981

Susceptibility of selected inbred strains of mice to Encephalitozoon cuniculi.

Selected inbred strains of mice were examined for susceptibility to peritoneal infections with Encephalitozoon cuniculi. Marked differences in susceptibility and resistance among mouse strains were not controlled by loci within the mouse major histocompatibility (H-2) complex, but resistance in BALB/c mice was influenced by a dominant gene(s) outside the H-2 complex. The lethality of peritoneal infections in hypothymic nude mice suggested that resistance to encephalitozoonosis is dependent on thymus-derived lymphocytes. Peritoneal infection with E. cuniculi was associated with slightly enhanced proliferative spleen cell responses to mitogens in BALB/c mice and significantly depressed responses in C57Bl/6 mice. Infection in BALB/c mice was accompanied by normal antibody responses to sheep erythrocyte immunogens, but C57Bl/6 mice had depressed antibody responses. The results indicate that the immune system plays a major role in determining the course of peritoneal infections with E. cuniculi and that encephalitozoonosis can modulate the host's immune system.

Animals↗
PubMed2003

Disseminated encephalitozoon cuniculi infection in a Mexican kidney transplant recipient.

BACKGROUND: No cases of Encephalitozoon cuniculi infection have been reported in transplant patients. METHODS: A 42-year-old man received a renal transplant 8 months earlier because of terminal glomerulonephritis and was admitted with cough, fever, diarrhea, abdominal pain, and colon wall thickening. While under rapamycin (2 g/day), cyclosporine A (4.4 mg/kg/day), and prednisone (100 mg/day) therapy, he developed Banff grade IB graft rejection and was treated with methylprednisolone (1 g/day) for 3 days and oral prednisone (60 mg/d). RESULTS: Microbiologic studies were inconclusive, and biopsy specimens of ileum, colon, liver, and the grafted kidney revealed numerous gram-positive microsporidia spores. Parasitophorous vacuoles containing various developing stages of Encephalitozoon were seen. Immunofluorescence studies identified the etiologic agent as E. cuniculi. Albendazole therapy resulted in clinical improvement but no eradication after 10 months of follow-up. CONCLUSIONS: This report describes what is, to the authors' knowledge, the first case of disseminated E. cuniculi infection in a kidney transplant human immunodeficiency virus-negative patient from Mexico.

Adult↗
PubMed1997

Microsporidia (Encephalitozoon cuniculi) in wild rabbits in Australia.

OBJECTIVE: To determine the prevalence of infection with Encephalitozoon cuniculi in wild rabbit populations in Western Australia, and to isolate the organism from seropositive rabbits. DESIGN: Serological screening of wild and clinically affected domestic rabbit populations. SAMPLE POPULATION: Eighty-one wild rabbits from south-western Western Australia and 29 laboratory rabbits. PROCEDURE: Indirect immunofluorescence antibody technique and in-vitro amplification of parasite isolates in fibroblast cultures. RESULTS: Of the 81 wild rabbits and 29 laboratory rabbits, 20 and 22 respectively, had antibodies to E cuniculi. E cuniculi from the urine of one seropositive laboratory rabbit and from brain and kidney tissues of eight and five seropositive laboratory and wild rabbits respectively were isolated in fibroblast cultures. CONCLUSION: E cuniculi infection has been shown for the first time to be prevalent in wild rabbits in Australia. Techniques have been developed for the isolation and culture of the causative agent. Comparative studies can now be undertaken to determine risk factors for clinical disease in domestic rabbits and the relationship among E cuniculi isolates from wild and domestic rabbits.

Animals↗
PubMed2006

Expression of two cell wall proteins during the intracellular development of Encephalitozoon cuniculi: an immunocytochemical and in situ hybridization study with ultrathin frozen sections.

The microsporidian Encephalitozoon cuniculi is an obligate intracellular parasite that develops asynchronously inside parasitophorous vacuoles. Spore differentiation involves the construction of a cell wall commonly divided into an outer layer (exospore) and a thicker, chitin-rich inner layer (endospore). The developmental patterns of protein deposition and mRNA expression for 2 different spore wall proteins were studied using immunocytochemical and in situ hybridization procedures with ultrathin frozen sections. The onset of deposition of an exospore-destined protein (SWP1) correlated with the formation of lamellar protuberances during meront-to-sporont conversion. No evidence for a release of SWP1 towards the parasitophorous vacuole lumen was obtained. An endospore-destined protein (EnP1) was detected early on the plasma membrane of meronts prior to extensive accumulation within the chitin-rich layer of sporoblasts. swp1 mRNA was preferentially synthesized in early sporogony while enp1 mRNA was transcribed during merogony and a large part of sporogony. The level of both mRNAs was reduced in mature spores. Considering the availability of the E. cuniculi genome sequence, the application of nucleic and/or protein probes to cryosections should facilitate the screening of various genes for stage-specific expression during microsporidian development.

Animals↗
PubMed1979

Sensitivity of Encephalitozoon cuniculi to various temperatures, disinfectants and drugs.

Spores of Encephalitozoon cuniculi were exposed to various temperature or to disinfectants, and their infectivity was then tested on monolayer cultures of canine kidney cells. The maximum survival time for spores suspended in medium 199 was 1 day at -20 degrees C, 98 days at 4 degrees C, 6 days at 22 degrees C, and 2 days at 37 degrees C. Only 2.5% survived 30 min at 56 degrees C. Boiling for 5 min or autoclaving at 120 degrees C for 10 min killed all spores. Dry spores survived less than a week at 4 degrees C but at least 4 weeks at 22 degrees C. Exposure for 30 min to recommended working concentrations of 9 of the 11 disinfectants tested killed all spores. The growth-inhibition effect of 7 antibiotics and chemotherapeutics was studied on canine kidney cell culture inoculated with E. cuniculi. None could completely inhibit growth. The most effective was chloroquine phosphate which, at a concentration of 12.5 mg per 1000 ml culture medium and during a test period of 8 weeks, reduced the harvest of E. cuniculi to 31% of that from inoculated, untreated cultures.

Animals↗