Retrospective species identification of microsporidian spores in diarrheic fecal samples from human immunodeficiency virus/AIDS patients by multiplexed fluorescence in situ hybridization

Case series of intestinal microsporidiosis in non-HIV patients caused by Encephalitozoon hellem

Intestinal microsporidiosis is most often caused by Enterocytozoon bieneusi, and to a lesser extent by species of the genus Encephalitozoon. Until now, Encephalitozoon hellem was not clearly known to induce disease restricted to the intestine, or rarely in HIV subjects or in tropical countries. We report here 11 cases of delineated intestinal microsporidioses due to E. hellem diagnosed in France in non-HIV patients. Briefly, all patients were immunocompromised. They all suffered from diarrhoea, associated in nearly 50% of cases with weight loss. Concerning treatment, 5/11 patients had a discontinuation or a decrease of their immunosuppressive therapy, and 4/11 received albendazole. All patients recovered. Five different genotypes were identified based on the rRNA ITS sequence.

Evaluation of the Bio-Evolution Microsporidia generic and typing real-time PCR assays for the diagnosis of intestinal microsporidiosis

Cases of intestinal microsporidiosis infection are underestimated and affect both immunocompromized and immunocompetent patients. Real-time PCR is superseding microscopic examination for its diagnosis in medical analysis laboratories. However, few manufacturers include microsporidia in their PCR panel for the diagnosis of infectious gastroenteritis. Here, we evaluated the performances of the real-time PCR assays microsporidia generic and microsporidia typing (Bio-Evolution, France) on the Rotor-Gene Q real-time PCR cycler (Qiagen, France). We included 45 negative and 44 positive stool samples for Enterocytozoon bieneusi (n = 34, with various genotypes), Encephalitozoon intestinalis (n = 4), Encephalitozoon hellem (n = 4), and Encephalitozoon cuniculi (n = 2). We also studied a four-year survey of an inter-laboratory quality control program including 9 centers that used this commercial assay. Sensitivity and specificity of the microsporidia generic assay were 86.4% and 93.3%, respectively. Encephalitozoon hellem and Encephalitozoon cuniculi were detected by the microsporidia generic PCR assay but not by the microsporidia typing PCR assay. These results were consistent with the results of the inter-laboratory quality control program. In conclusion, Bio-Evolution Real-time PCR assays are useful tools for intestinal microsporidiosis, but negative results for microsporidia typing assays require supplementary analyses to confirm E. hellem or E. cuniculi infections.

Characterizing the Proliferation Patterns of Representative Microsporidian Species Enlightens Future Studies of Infection Mechanisms

Background: Microsporidia are a group of pathogens that infect all kinds of animals, such as humans, silkworms, honeybees, and shrimp; they, therefore, pose a severe threat to public health and the economy. There are over 1500 species of microsporidia that have been reported, among which Encephalitozoon hellem and Nosema bombycis are the representative zoonotic and insect-infecting species, respectively. Investigating their cell infection patterns is of great significance for understanding their infection mechanisms. Methods: Specific probes were designed for the ribosomal RNA sequences of microsporidia. Fluorescence in situ hybridization (FISH) was used to trace the proliferation cycle of the pathogens in different cells. Results: Here, two rRNA large subunit gene (LSUrRNA) probes specifically labeling N. bombycis were obtained. The life cycle of N. bombycis in silkworm cells and E. hellem in three kinds of host cells was graphically drawn. N. bombycis meronts were first observed at 30 hours post-infection (hpi), and they began merogony. Sporonts were observed at 42 hpi, and the first entire proliferation cycle was completed at 48 hpi. The proliferation cycle of E. hellem in RK13 and HEK293 epithelial cells was almost the same, completing the first life cycle after 24 hpi, but it was significantly delayed to 32 hpi in RAW264.7. Conclusions: Specific FISH probes were established for labeling microsporidia in multiple host cells. The proliferation characteristics of representative zoonotic and insect-infecting microsporidian species were clarified. This study provides an experimental pattern for future analyses of microsporidian infection mechanisms.

Microsporidia Promote Host Mitochondrial Fragmentation by Modulating DRP1 Phosphorylation

Microsporidia are obligate intracellular parasites that infect a wide variety of hosts ranging from invertebrates to vertebrates. These parasites have evolved strategies to directly hijack host mitochondria for manipulating host metabolism and immunity. However, the mechanism of microsporidia interacting with host mitochondria is unclear. In the present study, we show that microsporidian Encephalitozoon greatly induce host mitochondrial fragmentation (HMF) in multiple cells. We then reveal that the parasites promote the phosphorylation of dynamin 1-like protein (DRP1) at the 616th serine (Ser616), and dephosphorylation of the 637th serine (Ser637) by highly activating mitochondrial phosphoglycerate mutase 5 (PGAM5). These phosphorylation modifications result in the translocation of DRP1 from cytosol to the mitochondrial outer membrane, and finally lead to HMF. Furthermore, treatment with mitochondrial division inhibitor 1 (Mdivi1) significantly reduced microsporidian proliferation, indicating that the HMF are crucial for microsporidian replication. In summary, our findings reveal the mechanism that microsporidia manipulate HMF and provide references for further understanding the interactions between these ubiquitous pathogens with host mitochondria.

Diagnosis and molecular typing of Enterocytozoon bieneusi: the significant role of domestic animals in transmission of human microsporidiosis

Enterocytozoon bieneusi is an obligate intracellular fungus-like parasite with high genetic diversity among mammalian and avian hosts. Based on polymorphism analysis of the ribosomal internal transcribed spacer (ITS), nearly 500 genotypes were identified within E. bieneusi. Those genotypes form several genetic groups that exhibit phenotypic differences in host specificity and zoonotic potential and probably have varying public health implications. Some of the genotypes in Group 1 (e.g., D, EbpC, and Type IV) and Group 2 (e.g., BEB4, BEB6, I, and J) are the most common ones that infect a variety of hosts including humans and thus are of public health importance. By contrast, those genotypes in other genetic groups (Groups 3-11) are mostly restricted to the hosts from which they were originally isolated, which would have unknown or limited impacts on public health. Advances on diagnosis and molecular typing of E. bieneusi are introduced in this review. Genotype distribution pattern of E. bieneusi in major domestic animal groups (pigs, cattle, sheep, goats, cats, and dogs), the role of those animals in zoonotic transmission of microsporidiosis, and food and water as potential vehicles for transmission are interpreted here as well. This review highlights the importance of including more genetic or epidemiological data obtained in the same geographical areas and using more reliable genetic markers to analyze the actual extent of host specificity in E. bieneusi, for the purpose of fully appreciating zoonotic risks of those domestic animals in close contacts with men and enhancing our understanding of the modes of transmission.

A specific molecular label for identifying mature Nosema bombycis spores

Microsporidia are a fascinating phylum of obligate intracellular pathogens with unique infection processes and complicated life cycles. Microsporidian life cycles can be divided roughly into intracellular and extracellular stages. Currently, research on their life cycles were mainly explored by morphology because there are few molecular markers available with which to distinguish the different life stages. In this study, we generated H20, a monoclonal antibody (MAb) to label mature spores of Nosema bombycis. Immunofluorescence assays showed that the target protein of H20, which is highly stable and was barely affected by alkali and sodium dodecyl sulfate (SDS) treatments, was located on the mature spore surface. Western blot analysis showed that spore wall protein 26 (SWP26) was the likely target of H20. This MAb can specifically identify mature spores in a complex biological sample based on immunological detection of the parasite.

Multimethodological Approach to Gastrointestinal Microsporidiosis in HIV-Infected Patients

PURPOSE

Microsporidiosis is an opportunistic infection that produces chronic diarrhoea and cholangiopathy in patients with AIDS, mainly caused by two species of microsporidia, Enterocytozoon bieneusi and Encephalitozon intestinalis. The aim of this work was to develop an integral system for the diagnosis of microsporidiosis of the intestine and biliary tract in HIV-infected patients, comprising microscopic and molecular techniques.

METHODS

The study population comprised 143 adult patients of both sexes with diagnosis of HIV infection, with chronic diarrhoea, and with or without HIV-associated cholangiopathy. Stool studies for microsporidia identification of spores were performed on each patient. A video esofagogastroduodenoscopy with biopsy collection was also carried out for routine histology and semi-thin sections stained with Azure II. Species identification was carried out by transmission electron microscopy and/or polymerase chain reaction for the species E. bieneusi and E. intestinalis.

RESULTS

Out of the 143 patients a total of 12.6% (n = 18) were infected with microsporidia. Microsporidia species identified in most cases was E. bieneusi (16/18 cases), followed by E. intestinalis (4/18), all of these last ones in coinfection with E. bieneusi.

CONCLUSIONS

Clinical, imaging, microscopic and molecular analyses, when applied in a systematic and integrated approach, allow diagnosis and identification of microsporidia at species level in AIDS patients with chronic diarrhoea, and with or without HIV-associated cholangiopathy.

Easy labeling of proliferative phase and sporogonic phase of microsporidia Nosema bombycis in host cells

Microsporidia are eukaryotic, unicellular parasites that have been studied for more than 150 years. These organisms are extraordinary in their ability to invade a wide range of hosts including vertebrates and invertebrates, such as human and commercially important animals. A lack of appropriate labeling methods has limited the research of the cell cycle and protein locations in intracellular stages. In this report, an easy fluorescent labeling method has been developed to mark the proliferative and sporogonic phases of microsporidia Nosema bombycis in host cells. Based on the presence of chitin, Calcofluor White M2R was used to label the sporogonic phase, while β-tubulin antibody coupled with fluorescence secondary antibody were used to label the proliferative phase by immunofluorescence. This method is simple, efficient and can be used on both infected cells and tissue slices, providing a great potential application in microsporidia research.

The role of microsporidian polar tube protein 4 (PTP4) in host cell infection

Microsporidia have been identified as pathogens that have important effects on our health, food security and economy. A key to the success of these obligate intracellular pathogens is their unique invasion organelle, the polar tube, which delivers the nucleus containing sporoplasm into host cells during invasion. Due to the size of the polar tube, the rapidity of polar tube discharge and sporoplasm passage, and the absence of genetic techniques for the manipulation of microsporidia, study of this organelle has been difficult and there is relatively little known regarding polar tube formation and the function of the proteins making up this structure. Herein, we have characterized polar tube protein 4 (PTP4) from the microsporidium Encephalitozoon hellem and found that a monoclonal antibody to PTP4 labels the tip of the polar tube suggesting that PTP4 might be involved in a direct interaction with host cell proteins during invasion. Further analyses employing indirect immunofluorescence (IFA), enzyme-linked immunosorbent (ELISA) and fluorescence-activated cell sorting (FACS) assays confirmed that PTP4 binds to mammalian cells. The addition of either recombinant PTP4 protein or anti-PTP4 antibody reduced microsporidian infection of its host cells in vitro. Proteomic analysis of PTP4 bound to host cell membranes purified by immunoprecipitation identified transferrin receptor 1 (TfR1) as a potential host cell interacting partner for PTP4. Additional experiments revealed that knocking out TfR1, adding TfR1 recombinant protein into cell culture, or adding anti-TfR1 antibody into cell culture significantly reduced microsporidian infection rates. These results indicate that PTP4 is an important protein competent of the polar tube involved in the mechanism of host cell infection utilized by these pathogens.

Microsporidia are obligate intracellular parasites that cause disease in immune suppressed individuals such as those with HIV/AIDS and recipients of organ transplants. The microsporidia are defined by a unique invasion organelle, the polar tube. The formation of this organelle and its role in the mechanism of infection remain unknown. Herein, we have identified a role for Encephalitozoon hellem polar tube protein 4 (PTP4) in infection demonstrating that PTP4 can bind to the host cell surface via the host transferrin receptor 1 (TfR1) protein. Interfering with the interaction of PTP4 and TfR1 causes a significant decrease in microsporidian infection of host cells. These data suggest that PTP4 functions as an important microsporidian protein during host cell infection by this pathogen.

Transmission of Dientamoeba fragilis: pinworm or cysts?

Recently, conflicting evidence has been published on the mode of transmission of the trichomonad Dientamoeba fragilis. Detection of D. fragilis DNA inside Enterobius vermicularis eggs agrees with the prediction of Dobell in 1940 that the eggs of a nematode act as a vector for transmission. However, the identification of a cyst stage of D. fragilis in the stool of rodents infected with a human isolate has also been reported, and this implies a life cycle similar to those of most other intestinal protistan parasites. Herein we discuss the recent data, identify gaps in the experimental evidence, and propose a method for determining which view of the life cycle of this organism is correct.

Prevalence, intensity and complications of Microsporidium spores amongst HIV-positive hospital patients in Ilorin, Nigeria

BACKGROUND

Microsporidiasis, which is of great concern for immunocompromised patients, is poorly studied in developing countries.

OBJECTIVES

A study was carried out amongst HIV-positive hospital patients and HIV-negative hospital controls in Ilorin, Nigeria, between January 2009 and July 2010 to determine the prevalence and intensity of Microsporidium spores and the complications associated with their presence.

METHOD

Stool samples from 750 HIV-positive patients and 375 HIV-negative patients were studied using the Chromotrope-2R staining technique. Determination of CD4+ count was performed on the Partec Cyflow SL-3 CD4/8 instrument. Intensity of spores was determined by counting the total number of the spores in a 10 µl stained smear of stool. Images were captured with Phenix Microimage Analysis Software and data obtained were analysed using the Statistical Package for the Social Sciences.

RESULTS

The prevalence of Microsporidium isolates amongst the HIV-positive hospital patients was significantly higher (42.4%) than amongst the HIV-negative controls (19.2%) (p < 0.05). The intensity of microsporidial spores amongst HIV-positive hospital patients was also significantly higher than amongst the controls (p < 0.05). However, the difference in the intensity of spores amongst HIV-positive patients who were on antiretroviral therapy (n = 411) and those who were not (n = 339) was not significant (p = 0.236). Microsporidiasis in HIV infection infection was common amongst patients with with low CD4+ counts, diarrhoea, body rashes and cough.

CONCLUSION

Both the prevalence and intensity of Microsporidiasis are high amongst HIV-positive hospital patients; campaigns to promote awareness, prevention and control are required. Laboratory testing for microsporidia in HIV patients should be performed routinely so as to identify the organism for prompt medical attention.

Specific detection and localization of microsporidian parasites in invertebrate hosts by using in situ hybridization

We designed fluorescence in situ hybridization probes for two distinct microsporidian clades and demonstrated their application in detecting, respectively, Nosema/Vairimorpha and Dictyoceola species. We used them to study the vertical transmission of two microsporidia infecting the amphipod Gammarus duebeni.

Microsporidial infections due toEncephalitozoon intestinalisin non-HIV-infected patients with chronic diarrhoea

We determined the prevalence of microsporidiaEnterocytozoon(Ent.)bieneusiandEncephalitozoon(E.)intestinalisinfection in patients with chronic diarrhoea and hepatocellular carcinoma (HCC). A total of 330 stool samples were examined from 171 (52%) patients with chronic diarrhoea, 18 (5%) with HCC while 141 (43%) were controls. Stool microscopy, polymerase chain reaction (PCR) with species-specific primers forEnt. bieneusiandE. intestinalisand sequencing were carried out. Microsporidia were found by trichrome staining in 11/330 (3%) andE. intestinalisby PCR in 13/330 (4%) whileEnt. bieneusiwas not detected. PCR forE. intestinaliswas positive in 8/171 (5%) stool samples from patients with chronic diarrhoea, 2/141 (1·4%) samples from healthy controls and in 3/18 (17%) samples from patients with HCC. In the chronic diarrhoea group,E. intestinaliswas positive in 4/171 (2·3%) (P=0·69) stool samples compared to 2/18 (11%) (P=0·06) in the HCC group and 2/141 (1·4%) from healthy controls.E. intestinalisinfection was significantly associated with chronic diarrhoea and HCC in these patients who were negative for HIV. Stool examination with trichrome or species-specific PCR for microsporidia may help establish the cause of chronic diarrhoea.

Encephalomyelitis associated with microsporidian infection in farmed greater amberjack, Seriola dumerili (Risso)

An outbreak of a disease characterized by a peculiar spiral movement in farmed greater amberjack, Seriola dumerili (Risso), occurred in Kagoshima Prefecture, Japan, in May 2008, immediately after importing the fish from China. Although neither bacteria nor viruses were detected in routine diagnostic tests, histopathological observations of the affected fish revealed severe inflammation in the tegmentum of the brain including the medulla oblongata and the anterior part of the spinal cord. In addition, a microsporidian parasite was observed in the nerve cell bodies or axons in the inflamed tissues. We identified a microsporidian small subunit rRNA gene (SSU rDNA) from the lesion, and the sequence showed 96.1% identity with that of Spraguea lophii. Subsequent in situ hybridization using probes presumably specific to the SSU rRNA confirmed that the parasite observed in histopathology harboured the identified SSU rRNA. Apparently degenerated microsporidian cells or spores were also frequently observed in tissue sections. Thus, the disease was most probably caused by the infection of a hitherto unknown microsporidian parasite that has a genetic affinity to the genus Spraguea, in the central nervous system of the amberjack.

Microsporidia are natural intracellular parasites of the nematode Caenorhabditis elegans

For decades the soil nematode Caenorhabditis elegans has been an important model system for biology, but little is known about its natural ecology. Recently, C. elegans has become the focus of studies of innate immunity and several pathogens have been shown to cause lethal intestinal infections in C. elegans. However none of these pathogens has been shown to invade nematode intestinal cells, and no pathogen has been isolated from wild-caught C. elegans. Here we describe an intracellular pathogen isolated from wild-caught C. elegans that we show is a new species of microsporidia. Microsporidia comprise a large class of eukaryotic intracellular parasites that are medically and agriculturally important, but poorly understood. We show that microsporidian infection of the C. elegans intestine proceeds through distinct stages and is transmitted horizontally. Disruption of a conserved cytoskeletal structure in the intestine called the terminal web correlates with the release of microsporidian spores from infected cells, and appears to be part of a novel mechanism by which intracellular pathogens exit from infected cells. Unlike in bacterial intestinal infections, the p38 MAPK and insulin/insulin-like growth factor (IGF) signaling pathways do not appear to play substantial roles in resistance to microsporidian infection in C. elegans. We found microsporidia in multiple wild-caught isolates of Caenorhabditis nematodes from diverse geographic locations. These results indicate that microsporidia are common parasites of C. elegans in the wild. In addition, the interaction between C. elegans and its natural microsporidian parasites provides a system in which to dissect intracellular intestinal infection in vivo and insight into the diversity of pathogenic mechanisms used by intracellular microbes.

The small roundworm Caenorhabditis elegans is an important model system for many areas of biology, but little is known about its natural ecology. We have identified an intracellular parasite from C. elegans in its natural habitat isolated near Paris and have named it Nematocida parisii, or nematode-killer from Paris. N. parisii defines a new genus and species of microsporidia. Microsporidia are ubiquitous eukaryotic pathogens that are thought to be highly reduced fungi and are emerging pathogens of humans. The microsporidian N. parisii invades and resides in C. elegans intestinal cells where it goes through a multistep life cycle and eventually escapes out of intestinal cells, leaving holes in the terminal web, an important cellular structure. We have found N. parisii and a related Nematocida species in several wild-caught roundworms, indicating that microsporidian infections may be relatively common for C. elegans in the wild. The C. elegans/N. parisii interaction provides a valuable system in which to study microsporidian infections in a whole animal, and a convenient and inexpensive system in which to screen for anti-microsporidian drugs.

A newly identified intracellular pathogen of wild-caughtCaenorhabditis elegans represents a new microsporidian species that will provide a model to study this class of pathogen in humans.

The role of birds in dissemination of human waterborne enteropathogens

Cryptosporidiosis, giardiasis and microsporidiosis are serious human diseases of waterborne origin; their etiologic agents and a substantial fecal coliform load can enter surface, drinking and recreational water resources from aquatic birds. The aim of this article is to present interactions between waterfowl and these waters that imply a negative public health impact, reinforcing the need for either better water-quality indicators or for water monitoring specifically for Cryptosporidium, Giardia and microsporidia. Where justifiable, the presence of waterfowl should be supported; however, management of drinking and recreational water resources needs to be improved by incorporating effective protection measures for pathogens linked to these birds.

Outbreak of microsporidiosis caused by Enterocytozoon bieneusi in falcons

Four falcons from a private collection of 137 falcons in Abu Dhabi (UAE) died suddenly in summer 2005. In order to screen for a possible disease among the remaining falcons in the aviary, all other birds were caught, examined and treated if necessary. Most of the falcons suffered from massive lice infestation and 74 falcons additionally from a heavy Caryospora sp. burden. Endoscopy revealed yellowish plaques on intestines, livers or kidneys in 70 birds (51.1% morbidity). Proliferative serositis was seen in 17 out of 24 necropsied birds with plaques on intestines, livers or kidneys, which did not resemble any known disease in falcons. However, apart from 20 falcons, which died within a 6-week period after the initial examinations due to advanced disease stages, all other falcons responded well to the treatment with dimetridazole (Emtryl), indicating protozoal disease. Immunohistochemistry confirmed the presence of microsporidial antigen. The final diagnosis of Enterocytozoon (E.) bieneusi genotype D was confirmed with materials from 6 birds by PCR and sequencing. To our knowledge this is the first report of microsporidiosis caused by E. bieneusi in raptors in general and in falcons in particular. However, it is still unclear for how long E. bieneusi was present in the falcon flock, and which role it played in the development of the disease. Predisposing factors such as high temperature and overcrowding in the aviary induced immune suppression causing massive lice infestation as well as coccidiosis, thus paving the way for invasion with microsporidial spores.

The effect of a taste-enhancement process for cold-stored raw shell-stock oysters (Crassostrea virginica) on the spillage of human enteropathogens

A taste-enhancement process for cold-stored, raw shell-stock Crassostrea virginica oysters (i.e., application of table salt to shells) when externally contaminated with human enteropathogens intensified spillage of these enteropathogens to oyster' storage containers (77% compared to 27% for controls) but did not, however, cause contamination of edible oyster tissue.

Quality of reclaimed waters: a public health need for source tracking of wastewater-derived protozoan enteropathogens in engineered wetlands

Demand for high-quality drinking and recreational water rises exponentially owing to global demographic growth in the human population, reinforcing an urgent need for microbiologically safe reclaimed water. However, constructed wetlands, implemented into municipal wastewater treatment, may not provide substantial remediation for human protozoan enteropathogens such as Cryptosporidium, Giardia and human-virulent microsporidia. Improving reclaimed water quality by lowering faecal coliforms is not a sound solution for these pathogens. Current advances in molecular technology can benefit public health in developing and developed countries by changing the conceptual research framework for wastewater-receiving wetlands from 'pathogen removal' to 'pathogen source tracking' efforts.

Quantitative assessment of contamination of fresh food produce of various retail types by human-virulent microsporidian spores

This study demonstrated that fresh food produce, such as berries, sprouts, and green-leafed vegetables, sold at the retail level can contain potentially viable microsporidian spores of human-virulent species, such as Enterocytozoon bieneusi, Encephalitozoon intestinalis, and Encephalitozoon cuniculi, at quantities representing a threat of food-borne infection.