Immune response to the filaria Litomosoides sigmodontis in susceptible and resistant mice.

Comparisons were made between the immune responses evoked during the course of chronic and patient infections of Litomosoides sigmodontis in susceptible BALB/c mice and non-patent infections in resistant B10.D2 mice. Early antigen specific responses of spleen cells were weak in both mouse strains. However, by day 58 post infection a strong Th2 response, as determined by production of IL-4, IL-5 and IL-10, was observed in BALB/c mice but not in B10.D2 mice. Antibody responses seemed to appear sooner in B10.D2 than in BALB/c mice, and these differentially recognised two antigens of 15 kD and 80 kD.

Specific PCR assay for direct detection of intestinal microsporidia Enterocytozoon bieneusi and Encephalitozoon intestinalis in fecal specimens from human immunodeficiency virus-infected patients.

A routine assay based on the PCR was developed for the detection of Enterocytozoon bieneusi and Encephalitozoon intestinalis in fecal samples. Two oligonucleotide primer pairs from a conserved region in the small-subunit rRNA genes of E. bieneusi (primer pair V1 and EB450) and E. intestinalis (primer pair V1 and SI500) were used to amplify microsporidian DNA. We achieved specific amplification of a 382-bp DNA fragment in E. intestinalis and a 353-bp DNA fragment in E. bieneusi. Boiling of the samples appeared to be most effective for DNA extraction. Fecal samples containing fewer than 10 microsporidia gave a positive result in the PCR assay. Fecal specimens from 30 human immunodeficiency virus-infected patients with microsporidiosis and fecal specimens from 42 patients suspected of having microsporidiosis were investigated by the PCR assay. The PCR assay was validated against standard staining methods (the Uvitex 2B and Chromotrope 2R staining methods) and immunofluorescence assay specific for E. intestinalis. This comparative study has shown that PCR improved species determination and can thus be considered a fast and reliable method for the detection and identification of each intestinal species.

Experimental model for human intestinal microsporidiosis in interferon gamma receptor knockout mice infected by Encephalitozoon intestinalis.

Interferon gamma receptor knockout mice developed a chronic infection when inoculated with spores of Encephalitozoon intestinalis which is a cause of intestinal microsporidiosis in AIDS patients. The infection was evaluated by enumeration of the spores of the parasite shed in the stools, histological examination and follow up over a period of six months. A dose-response was demonstrated since higher numbers of spores were excreted and more infection sites were found in mice which were given an increased quantity of parasites. In infected wild type mice, the number of excreted spores decreased until day 16 post-inoculation, then spores were detected sporadically in low numbers. These data confirmed the role of IFN-gamma in the control of E. intestinalis infection. The infection was not lethal suggesting that other factors are involved in regulation of the parasite infection. This model, with the long survival time of the animals together with the measurable quantity of spores shed in the stools will be useful for testing potential therapeutical agents.

Specific and rapid detection of Microsporidia in stool specimens from AIDS patients by PCR.

Two microsporidian species, Enterocytozoon bieneusi and Encephalitozoon intestinalis, are the cause of diarrhoea and wasting syndrome in AIDS patients. A new PCR assay is proposed for the rapid and specific detection of these parasites in stools.

Specific detection of the microsporidia Encephalitozoon intestinalis in AIDS patients.

The microsporidia Encephalitozoon intestinalis is an opportunistic pathogen responsible for severe gastrointestinal diseases and disseminated infection in AIDS patients. No light-microscopical method allows the specific detection of this unicellular parasite and up to this date, only electron microscopy could confirm the diagnosis of the species. We propose a method combining the non specific labelling of microsporidian spores by the fluorochrome Uvitex 2B and an indirect immunofluorescent assay with a polyclonal antibody specifically directed against E. intestinalis. Preliminary data demonstrate the specificity of this antibody. This method enables the distinction between E. intestinalis and Enterocytozoon bieneusi an other microsporidian also associated with gastrointestinal infection. Due to the precocious detection of E. intestinalis patients will be treated earlier with albendazole which is potentially active against this species.

Comparative development of two microsporidian species: Enterocytozoon bieneusi and Enterocytozoon salmonis, reported in AIDS patients and salmonid fish, respectively.

Enterocytozoon bieneusi and Enterocytozoon salmonis are reported in HIV-infected patients and in salmonid fish, respectively. Both species share the early development of the extrusion apparatus of the spores, which is completed prior to fission of the sporogonic syncytium into sporoblasts, and the early synthesis of polar tube constituents, but they differ in other developmental and sporogenetic processes. Enterocytozoon bieneusi develops in direct contact with the cytoplasm of epithelial cells whereas E. salmonis occurs only in the nucleus of leucocytes and epithelioid cells. Sporogonic nuclei, which are scattered throughout the sporont in E. bieneusi, are located in the periphery in E. salmonis. The multilamellar structures associated with the nuclear envelopes and the endoplasmic reticulum cisternae are specific for E. bieneusi. Additionally, the evolution of the polar tube precursors proceeds differently in the two parasites. In E. bieneusi, they transform into electron-dense bodies associated with a reticulum and polar tubes derive from these structures according to a process similar to that reported in other microsporidia. In E. salmonis, polar tube precursors fuse directly at their ends and the polar tubes appear to be formed by the assemblage of these fused precursors with a material previously synthesized in the vicinity of nuclei. In conclusion, both species appear to be less closely related than was supposed in earlier descriptions.

Use of cross-reactive antigens of the microsporidian Glugea atherinae for the possible detection of Enterocytozoon bieneusi by western blot.

The microsporidia Enterocytozoon bieneusi is reported in 10-30% of those infected with the human immunodeficiency virus. The parasite appears to be a cause of gastralgia, malabsorption, and diarrhea. A Western blot technique using another microsporidian species, Glugea atherinae, has demonstrated an antigenic similarity between this parasite and E. bieneusi. Preliminary results show the variability of the antigenic profiles obtained from the sera of immunodeficient patients infected with E. bieneusi and also of the cross-reactivity to Glugea sp. antigens of some sera from patients with cryptosporidiosis. The origin of this cross-reactivity is undetermined. The possibility of coinfection with undetected microsporidia is not excluded. These results raise questions concerning the interpretation of serologic data and of the potential immunodiagnostic value of microsporidian antigens.

The phospholipids in Enterocytozoon bieneusi: an electron spectroscopic imaging study.

The treatment with ferriosmium of meronts and sporonts of the microsporidian Enterocytozoon bieneusi has shown the lamellar organization of the membranes of the endoplasmic reticulum and of the nuclear envelope. The Electron Spectroscopy Imaging (ESI), (Ottensmeyer and Andrew 1980) of unstained ultrathin sections of meronts showed the presence of phosphorus in the lamellar structures thus confirming their phospholipidic composition. Phosphorus was also detected in the lamellar polaroplast of the spore.