Encephalitozoon cuniculi and Vittaforma corneae (Phylum Microsporidia) inhibit staurosporine-induced apoptosis in human THP-1 macrophages in vitro.

Obligately intracellular microsporidia regulate their host cell life cycles, including apoptosis, but this has not been evaluated in phagocytic host cells such as macrophages that can facilitate infection but also can be activated to kill microsporidia. We examined two biologically dissimilar human-infecting microsporidia species, Encephalitozoon cuniculi and Vittaforma corneae, for their effects on staurosporine-induced apoptosis in the human macrophage-differentiated cell line, THP1. Apoptosis was measured after exposure of THP-1 cells to live and dead mature organisms via direct fluorometric measurement of Caspase 3, colorimetric and fluorometric TUNEL assays, and mRNA gene expression profiles using Apoptosis RT2 Profiler PCR Array. Both species of microsporidia modulated the intrinsic apoptosis pathway. In particular, live E. cuniculi spores inhibited staurosporine-induced apoptosis as well as suppressed pro-apoptosis genes and upregulated anti-apoptosis genes more broadly than V. corneae. Exposure to dead spores induced an opposite effect. Vittaforma corneae, however, also induced inflammasome activation via Caspases 1 and 4. Of the 84 apoptosis-related genes assayed, 42 (i.e. 23 pro-apoptosis, nine anti-apoptosis, and 10 regulatory) genes were more affected including those encoding members of the Bcl2 family, caspases and their regulators, and members of the tumour necrosis factor (TNF)/TNF receptor R superfamily.

Fast Technology Analysis Enables Identification of Species and Genotypes of Latent Microsporidia Infections in Healthy Native Cameroonians.

Several enteric microsporidia species have been detected in humans and other vertebrates and their identifications at the genotype level are currently being elucidated. As advanced methods, reagents, and disposal kits for detecting and identifying pathogens become commercially available, it is important to test them in settings other than in laboratories with "state-of-the-art" equipment and well-trained staff members. In the present study, we sought to detect microsporidia DNA preserved and extracted from FTA (fast technology analysis) cards spotted with human fecal suspensions obtained from Cameroonian volunteers living in the capital city of Yaoundé to preclude the need for employing spore-concentrating protocols. Further, we tested whether amplicon nucleotide sequencing approaches could be used on small aliquots taken from the cards to elucidate the diversity of microsporidia species and strains infecting native residents. Of 196 samples analyzed, 12 (6.1%) were positive for microsporidia DNA; Enterocytozoon bieneusi (Type IV and KIN-1), Encephalitozoon cuniculi, and Encephalitozoon intestinalis were identified. These data demonstrate the utility of the FTA cards in identifying genotypes of microsporidia DNA in human fecal samples that may be applied to field testing for prevalence studies.

Encephalitozoon cuniculi-Associated Equine Encephalitis: A Case Report.

A case of encephalitis of unknown origin in the horse was investigated. Postmortem examination findings revealed a nonsuppurative granulomatous meningoencephalitis in the right hemisphere of the cerebral cortex. Testing for West Nile virus, equine herpes virus, equine infectious anemia, Toxoplasma gondii, Neospora caninum, and Sarcocystis neurona were negative. The horse had a titer for Encephalitozoon cuniculi, and sections from the affected area of the brain tested positive for the organism using both polymerase chain reaction (PCR) and immunohistochemistry. Amplicons generated using PCR were sequenced, and E. cuniculi genotype II was identified. This is the first case of E. cuniculi genotype II associated with encephalitis in the horse.

Transcriptome analysis of the parasite Encephalitozoon cuniculi: an in-depth examination of pre-mRNA splicing in a reduced eukaryote.

BACKGROUND: The microsporidian Encephalitozoon cuniculi possesses one of the most reduced and compacted eukaryotic genomes. Reduction in this intracellular parasite has affected major cellular machinery, including the loss of over fifty core spliceosomal components compared to S. cerevisiae. To identify expression changes throughout the parasite's life cycle and also to assess splicing in the context of this reduced system, we examined the transcriptome of E. cuniculi using Illumina RNA-seq. RESULTS: We observed that nearly all genes are expressed at three post-infection time-points examined. A large fraction of genes are differentially expressed between the first and second (37.7%) and first and third (43.8%) time-points, while only four genes are differentially expressed between the latter two. Levels of intron splicing are very low, with 81% of junctions spliced at levels below 50%. This is dramatically lower than splicing levels found in two other fungal species examined. We also describe the first case of alternative splicing in a microsporidian, an unexpected complexity given the reduction in spliceosomal components. CONCLUSIONS: Low levels of splicing observed are likely the result of an inefficient spliceosome; however, at least in one case, splicing appears to be playing a functional role. Although several RNA decay genes are encoded in E. cuniculi, the lack of a few key players could be reducing decay levels and therefore increasing the proportion of unspliced transcripts. Significant proportions of genes are differentially expressed in the first forty-eight hours but not after, indicative of genetic changes that precede the intracellular to infective stage transition.

Immune correlates of aging in outdoor-housed captive rhesus macaques (Macaca mulatta).

BACKGROUND: Questions remain about whether inflammation is a cause, consequence, or coincidence of aging. The purpose of this study was to define baseline immunological characteristics from blood to develop a model in rhesus macaques that could be used to address the relationship between inflammation and aging. Hematology, flow cytometry, clinical chemistry, and multiplex cytokine/chemokine analyses were performed on a group of 101 outdoor-housed captive rhesus macaques ranging from 2 to 24 years of age, approximately equivalent to 8 to 77 years of age in humans. RESULTS: These results extend earlier reports correlating changes in lymphocyte subpopulations and cytokines/chemokines with increasing age. There were significant declines in numbers of white blood cells (WBC) overall, as well as lymphocytes, monocytes, and polymorphonuclear cells with increasing age. Among lymphocytes, there were no significant declines in NK cells and T cells, whereas B cell numbers exhibited significant declines with age. Within the T cell populations, there were significant declines in numbers of CD4+ naïve T cells and CD8+ naïve T cells. Conversely, numbers of CD4+CD8+ effector memory and CD8+effector memory T cells increased with age. New multiplex analyses revealed that concentrations of a panel of ten circulating cytokines/chemokines, IFNγ, IL1b, IL6, IL12, IL15, TNFα, MCP1, MIP1α, IL1ra, and IL4, each significantly correlated with age and also exhibited concordant pairwise correlations with every other factor within this group. To also control for outlier values, mean rank values of each of these cytokine concentrations in relation to age of each animal and these also correlated with age. CONCLUSIONS: A panel of ten cytokines/chemokines were identified that correlated with aging and also with each other. This will permit selection of animals exhibiting relatively higher and lower inflammation status as a model to test mechanisms of inflammation status in aging with susceptibility to infections and vaccine efficacy.

Emerging microsporidian infections in Russian HIV-infected patients.

Microsporidia were identified in stool specimens by histochemistry and PCR of 30 (18.9%) of 159 HIV-infected patients presenting to the S. P. Botkin Memorial Clinical Hospital of Infectious Diseases, St. Petersburg, Russia. The higher prevalence of Encephalitozoon intestinalis, in 21 (12.8%) patients, than of Enterocytozoon bieneusi, in 2 patients (1.2%), was unexpected. Encephalitozoon cuniculi was detected in three patients: one with strain I and two with strain II. Encephalitozoon hellem was detected in one patient, and two patients were identified as being infected by Microsporidium species. One patient was infected with both E. intestinalis and E. cuniculi. In two patients, the microsporidian species were not identifiable. No statistically significant differences in gender, age, and stage of AIDS were observed between the microsporidian-positive and -negative HIV-infected patients. HIV-infected patients diagnosed with microsporidian infection, however, were significantly more likely to exhibit ≤ 100 CD4(+) T cells/µl blood (20/30 patients [67%]; odds ratio [OR], 3.150; 95% confidence interval [CI(95)], 1.280 to 7.750; P = 0.0116) and weight loss of >10% of the baseline (19/30 patients [63%]; odds ratio, 2.995; CI(95), 1.100 to 8.158; P = 0.0352) than HIV-infected patients not diagnosed with microsporidian infection. In summary, this is the first report describing the diagnosis of microsporidian infection of HIV-infected patients in Russia and the first detection of E. cuniculi strain II in a human.

Reactive nitrogen and oxygen species, and iron sequestration contribute to macrophage-mediated control of Encephalitozoon cuniculi (Phylum Microsporidia) infection in vitro and in vivo.

Encephalitozoon cuniculi (Phylum Microsporidia) infects a wide range of mammals, and replicates within resting macrophages. Activated macrophages, conversely, inhibit replication and destroy intracellular organisms. These studies were performed to assess mechanisms of innate immune responses expressed by macrophages to control E. cuniculi infection. Addition of reactive oxygen and nitrogen species inhibitors to activated murine peritoneal macrophages statistically significantly, rescued E. cuniculi infection ex vivo. Mice deficient in reactive oxygen species, reactive nitrogen species, or both survived ip inoculation of E. cuniculi, but carried significantly higher peritoneal parasite burdens than wild-type mice at 1 and 2 weeks post inoculation. Infected peritoneal macrophages could still be identified 4 weeks post inoculation in mice deficient in reactive nitrogen species. L-tryptophan supplementation of activated murine peritoneal macrophage cultures ex vivo failed to rescue microsporidia infection. Addition of ferric citrate to supplement iron, however, did significantly rescue E. cuniculi infection in activated macrophages and further increased parasite replication in non-activated macrophages over non-treated resting control macrophages. These results demonstrate the contribution of reactive oxygen and nitrogen species, as well as iron sequestration, to innate immune responses expressed by macrophages to control E. cuniculi infection.

Microsporidia intestinales en pacientes viviendo con SIDA en Honduras / Intestinal microsporidiosis in patients with AIDS in Honduras

ANTECEDENTES: Organismos pertenecientes al grupo Microspora son conocidos mundialmente como agentes de enfermedad oportunista en pacientes viviendo con SIDA. OBJETIVOS: Investigar la presencia de especies de microsporidia y la coinfección con parásitos intestinales en pacientes viviendo con SIDA en Honduras. METODOLOGÍA: Se examinó una muestra de heces de cada uno de 56 pacientes viviendo con SIDA del Hospital Mario Catarino Rivas, San PedroSula, Honduras, de mayo a agosto 1999, por la técnica de reacción en cadena de la polimerasa (PCR) y por coloraciones histoquímicas con Calcofluor Blanco 2MR y tricromo modificado y por cuatro métodos adicionales de rutina investigando la coinfección con parásitos intestinales. RESULTADOS: Se identificó esporas de microsporidia en 25 (14/56) de pacientes, por coloraciones histoquímicas de heces. La técnica de PCR, más sensitiva, identificó 41.5 (22/53) de pacientes con infección por microsporidia. Diez resultaron Enterocytozoon bieneusi o especies de Encephalitozoon; uno resultó E. bieneusi, 6 fueron positivos para Encephalitozoon spp, y 7 pertenecían a especies no determinadas. Diez y nueve de 22 individuos (86.3) identificados con esporas de microsporidia tenían también parásitos intestinales: Isospora belli (30.4), Strongyloides stercoralis (21.4), Ascaris lumbricoides(17.1), Cryptosporidium spp. (16.1), Trichuris trichiura (14.3) y uncinaria (10.7). Quistes de Giardia lamblia, Entamoeba histolytica/E. dispar,ooquistes de Cyclospora cayetanensis y huevos de Hymenolepis nana se encontraron en menor porcentaje.CONCLUSIÓN: Este estudio permitió identificar por primera vez infecciones por microsporidia intestinales en personas viviendo con SIDA en Honduras, solas o en asociación con otras infecciones por nemátodos,céstodos y protozoos comunes y/u oportunistas...

Microsporidia intestinales en pacientes viviendo con SIDA en Honduras / Intestinal microsporidiosis in AIDS patients from Honduras

ANTECEDENTES: Organismos pertenecientes al grupo Microspora son conocidos mundialmente como agentes de enfermedad oportunista en pacientes viviendo con SIDA. OBJETIVOS: Investigar la presencia de especies de microsporidia y la coinfección con parásitos intestinales en pacientes viviendo con SIDA en Honduras. METODOLOGÍA: Se examinó una muestra de heces de cada uno de 56 pacientes viviendo con SIDA del Hospital Mario Catarino Rivas, San PedroSula, Honduras, de mayo a agosto 1999, por la técnica de reacción en cadena de la polimerasa (PCR) y por coloraciones histoquímicas con Calcofluor Blanco 2MR y tricromo modificado y por cuatro métodos adicionales de rutina investigando la coinfección con parásitos intestinales. RESULTADOS: Se identificó esporas de microsporidia en 25% (14/56) de pacientes, por coloraciones histoquímicas de heces. La técnica de PCR, más sensitiva, identificó 41.5% (22/53) de pacientes con infección por microsporidia. Diez resultaron Enterocytozoon bieneusi o especies de Encephalitozoon; uno resultó E. bieneusi, 6 fueron positivos para Encephalitozoon spp, y 7 pertenecían a especies no determinadas. Diez y nueve de 22 individuos (86.3%) identificados con esporas de microsporidia tenían también parásitos intestinales: Isospora belli (30.4%), Strongyloides stercoralis (21.4%), Ascaris lumbricoides(17.1%), Cryptosporidium spp. (16.1%), Trichuris trichiura (14.3%) y uncinaria (10.7%). Quistes de Giardia lamblia, Entamoeba histolytica/E. dispar,ooquistes de Cyclospora cayetanensis y huevos de Hymenolepis nana se encontraron en menor porcentaje.CONCLUSIÓN: Este estudio permitió identificar por primera vez infecciones por microsporidia intestinales en personas viviendo con SIDA en Honduras, solas o en asociación con otras infecciones por nemátodos,céstodos y protozoos comunes y/u oportunistas...(AU)

Antimicrosporidial activities of fumagillin, TNP-470, ovalicin, and ovalicin derivatives in vitro and in vivo.

Therapies for microsporidiosis in humans are limited, and fumagillin, which appears to be the most broadly effective antimicrosporidial drug, is considered to be moderately toxic. The purpose of this study was to apply an in vitro drug screening assay for Encephalitozoon intestinalis and Vittaforma corneae and an in vivo athymic mouse model of V. corneae infection to assess the efficacy of TNP-470 (a semisynthetic analogue of fumagillin), ovalicin, and eight ovalicin derivatives. TNP-470, ovalicin, and three of the ovalicin derivatives inhibited both E. intestinalis and V. corneae replication by more than 70% in vitro. Another three of the ovalicin derivatives inhibited one of the two microsporidian species by more than 70%. None of the treated athymic mice survived the V. corneae infection, but they did survive statistically significantly longer than the untreated controls after daily treatment with fumagillin administered at 5, 10, and 20 mg/kg of body weight subcutaneously (s.c.), TNP-470 administered at 20 mg/kg intraperitoneally (i.p.), or ovalicin administered at 5 mg/kg s.c. Of two ovalicin derivatives that were assessed in vivo, NSC 9665 given at 10 mg/kg i.p. daily also statistically significantly prolonged survival of the mice. No lesions associated with drug toxicity were observed in the kidneys or livers of uninfected mice treated with these drugs at the highest dose of 20 mg/kg daily. These results thus support continued studies to identify more effective fumagillin-related drugs for treating microsporidiosis.

Natural and experimental infection of immunocompromised rhesus macaques (Macaca mulatta) with the microsporidian Enterocytozoon bieneusi genotype D.

Microsporidia are obligate intracellular parasites that cause opportunistic infections in AIDS and other immunocompromised patients. Eight simian immunodeficiency virus (SIV)-infected rhesus macaque monkeys (Macaca mulatta) were inoculated orally with Enterocytozoon bieneusi spores isolated from intestinal lavage fluid of an AIDS patient (genotype D) to study the natural history of this infection. Four monkeys were already naturally infected with E. bieneusi (also genotype D), and were included to determine if a second inoculum affected the course of illness. Spore shedding was detected in feces of all eight monkeys within the first week of experimental infection. Five monkeys died within 3.5 months of experimental E. bieneusi inoculation. Three of these five monkeys began the study with CD4+CD29+ T cell levels well below 20% of total T lymphocytes. Deaths were due to a variety of AIDS-related manifestations. Microsporidia did not appear to directly contribute to mortality but may have contributed to morbidity. At necropsy, microsporidia were found in bile and tissue sections of the gallbladder but not in the gut, kidneys, or liver. The percent CD4+CD29+ levels of the last three monkeys remained near the level observed at the time of inoculation. These monkeys lived more than 2 years after the end of the study and continued to shed spores. This study corroborates previous reports that E. bieneusi can be reliably transmitted to SIV-infected rhesus monkeys but indicates that the use of SIV-infected monkeys for the study of microsporidiosis is complicated by the confounding effect of other opportunistic or AIDS-related infections.

Assessment of the nasopharyngeal bacterial flora of rhesus macaques: moraxella, Neisseria, haemophilus, and other genera.

The nasopharyngeal bacterial flora of healthy rhesus macaques was surveyed for the presence of Neisseria and Haemophilus species, as well as Moraxella catarrhalis. M. catarrhalis was found both in healthy rhesus macaques and in possibly immunocompromised rhesus macaques. Several Haemophilus spp. that are part of the normal nasopharyngeal bacterial flora of humans were found in many animals; these Haemophilus species included H. parahaemolyticus, H. segnis, and H. parainfluenzae. While Haemophilus influenzae was not identified, it is possible that the identification of H. influenzae types may have been thwarted by the growth of less fastidious species. A number of animals harbored Neisseria spp. such as N. sicca. However, Neisseria meningitidis was not found. In summary, it appears as though the rhesus macaque may be used as a model for M. catarrhalis infections. Moreover, in view of the susceptibility of macaques to organisms of the Haemophilus and Neisseria genera, it is possible that these animals may also accurately model nontypeable H. influenzae and N. meningitidis infections.

An immune evasion mechanism for spirochetal persistence in Lyme borreliosis.

Borrelia burgdorferi, the Lyme disease spirochete, persistently infects mammalian hosts despite the development of strong humoral responses directed against the pathogen. Here we describe a novel mechanism of immune evasion by B. burgdorferi. In immunocompetent mice, spirochetes that did not express ospC (the outer-surface protein C gene) were selected within 17 d after inoculation, concomitantly with the emergence of anti-OspC antibody. Spirochetes with no detectable OspC transcript that were isolated from immunocompetent mice reexpressed ospC after they were either cultured in vitro or transplanted to naive immunocompetent mice, but not in OspC-immunized mice. B. burgdorferi persistently expressed ospC in severe combined immune-deficient (SCID) mice. Passive immunization of B. burgdorferi-infected SCID mice with an anti-OspC monoclonal antibody selectively eliminated ospC-expressing spirochetes but did not clear the infection. OspC-expressing spirochetes reappeared in SCID mice after the anti-OspC antibody was eliminated. We submit that selection of surface-antigen nonexpressers is an immune evasion mechanism that contributes to spirochetal persistence.