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PubMedDate not supplied

Production of extracellular collagenolytic proteinases by Histoplasma capsulatum var. duboisii and Histoplasma capsulatum var. capsulatum in the yeast phase.

Yeast cultures of Histoplasma capsulatum var. duboisii and H. capsulatum var. capsulatum in collagen containing defined, semi-defined and complex media produced extracellular collagenolytic proteinases, assayed using 4-phenylazo-benzyloxycarbonyl-L-propyl-L-leucyl- glycyl-L-propyl-D-arginine, a specific collagenase substrate. Significant levels of hydroxyproline were measured in the cultures and clear zones of hydrolysis were produced in collagen buffer agar by the crude enzyme preparations. Hydrolysis of casein and bovine serum albumin at pH 8 suggests the presence, in the crude enzymes, of multiple proteinases rather than a collagenase with broad substrate specificity since collagenolytic activity was not detected at pH 5 and above. Collagenolytic activities in the crude enzymes of both fungi were optimal at pH 4, 40 degrees C and were inhibited by EDTA, phosphoramidion and aprotinin indicating a metallo-serine nature. The molecular weights, estimated by column chromatography, were both 17 kD. The enzymes probably constitute a shared antigen. A probable role in the pathogenesis of histoplasmosis is discussed.

Amino Acid Sequence↗

PubMedDate not supplied

In vitro production of extracellular elastolytic proteinase by Histoplasma capsulatum var. duboisii and Histoplasma capsulatum var. capsulatum in the yeast phase.

Extracellular elastolytic proteinase was produced by yeast cultures of Histoplasma capsulatum var. duboisii and H. capsulatum var. capsulatum in three different induction media, assayed using elastin-orcein as the substrate. Medium-dependent variations in the time-course for enzyme production were observed and no peak was recorded. The proteinases hydrolysed both casein and bovine serum albumin indicating a broad substrate specificity. Both elastolytic proteinases had similar optimum pH (pH 8) and temperature (35 degrees C); over 90% residual elastolytic activity was measured in the crude enzymes of v. duboisii and v. capsulatum after incubation in the pH ranges 4.5-8.0 and 4.0-7.0 respectively, at 4 degrees C for 24 h. The proteinases were not significantly inhibited by any of the tested proteinase inhibitors. The molecular weights, estimated by column chromatography, were 23 kD. A probable role in the pathogenesis of histoplasmosis is discussed.

Histoplasma↗

PubMed1992

In vivo generation of linear plasmids with addition of telomeric sequences by Histoplasma capsulatum.

Histoplasma capsulatum is a dimorphic pathogenic fungus that is a major cause of respiratory and systemic mycosis. We previously developed a transformation system for Histoplasma and demonstrated chromosomal integration of transforming plasmid sequences. In this study, we describe another Histoplasma mechanism for maintaining transforming DNA i.e. the generation of modified, multicopy linear plasmids carrying DNA from the transforming Escherichia coli plasmid. Under selective conditions, these linear plasmids were stable and capable of retransforming Histoplasma without further modification. In vivo modification of the transforming DNA included duplication of plasmid sequence and telomeric addition at the termini of linear DNA. Apparently Histoplasma telomerase, like that of other organisms such as humans and Tetrahymena, is able to act on non-telomeric substrates. The terminus of a Histoplasma linear plasmid was cloned and shown to contain multiple repeats of GGGTTA, the telomeric repeat unit also found in vertebrates, trypanosomes, and slime moulds.

Base Sequence↗

PubMed1990

Histoplasma capsulatum endophthalmitis after cataract extraction.

A 60-year-old white man from an area endemic for Histoplasma capsulatum presented with a vitreous wick, hypopyon iritis, and dense vitreitis 2 months after removal of an anterior chamber intraocular lens (IOL) for chronic iritis. A diagnostic vitrectomy was performed and H. capsulatum was cultured and identified 2 weeks later. Despite intravitreal and intravenous amphotericin as well as repeat vitrectomies, the inflammation worsened and the eye was removed. Results of histopathologic examination showed Histoplasma organisms along the vitreous wick, over the surface of the iris and ciliary body, and over the retina. No organisms were found in the choroid. Dalen-Fuchs-type nodules similar to those of sarcoid also were noted, but there was no evidence of granulomatous inflammation in the uvea. Because of his unilateral disease with Histoplasma in the vitreous wick, negative serology, and an absence of systemic infection, the authors believe that this patient had a previously unreported form of ocular Histoplasma, exogenous postoperative Histoplasma endophthalmitis.

Cataract Extraction↗

PubMed1989

Significance of Histoplasma antigen in the cerebrospinal fluid of patients with meningitis.

A radioimmunoassay was previously developed for detection of Histoplasma capsulatum antigen in the blood and urine of patients with disseminated histoplasmosis. In this investigation, cerebrospinal fluid (CSF) specimens from 14 episodes of Histoplasma meningitis occurring in 12 patients were tested by radioimmunoassay. Histoplasma capsulatum antigen was detected in the CSF of five patients. Cerebrospinal fluid cultures were positive for H capsulatum in three of these five patients. Antibodies to H capsulatum were found in nine of the 13 CSF specimens tested. The radioimmunoassay for Histoplasma antigen was also positive in the CSF in one of 11 patients with coccidioidal meningitis but not in 17 patients with cryptococcal meningitis. It was concluded that Histoplasma antigen is present in the CSF of some patients with histoplasmosis and chronic meningitis, but cross-reactions may occur in patients with coccidioidal meningitis.

Antigens, Fungal↗

PubMed1977

Histoplasma meningitis with common variable hypogammaglobulinemia.

Histoplasma meningitis (HM) has been reported to occur primarily in association with disseminated histoplasmosis (DH). We report a case of histoplasma meningitis occurring in a patient with common variable hypogammaglobulinemia (CVH) in which no manifestations of DH were observed. L. L., a 66-year-old Caucasian male, clerical worker, developed occasional episodes of dizziness and tinnitus in mid-1971. During 1972, increasing frequency of these episodes and gradually progressive confusion were noted. In January 1973, vomiting, forther confusion, obnubilation, and a left central facial paresis developed and he was hospitalized. Physical examination revealed no pulmonary abnormalities, lymphadenopathy or hepatosplenomegaly. Over the ensuing 6-week evaluation, there was occasional fever to 38.5 degrees C. Chest roentgenogram was normal. Cerebral angiography suggested a mass in the left cerebellar hemisphere. EEG was diffusely slow. Multiple CSF examinations revealed: Glucose 7-18 mg/with a normal blood glucose, protein 109-256 mg/and cells 66-140 (95 + % mononuclear). Histoplasma capsulatum was cultured from CSF but not from sputum, urine, blood or bone marrow. Skin tests for PPD, histoplasmosis, coccidiodomycosis, blastomycosis, mumps, dinitrochlorobenzene and streptokinase-streptodornase were negative then and 6 months later. Histoplasma serum antibody was absent. Immunoglobulin analysis revealed IgG 430 mg %, IgA 46 mg %, and IgM 35 mg %, which with the history and skin test results suggested CVH. Treatment with 2.51 gm of amphotericin B given intravenously over a 3-month period resulted in complete reversal of all neurologic signs and clearing of the confusion. The remission has been maintained for two years. This case represents a primary infection of the CNS by histoplasma. The relationship between the HM and the CVH will be discussed.

Agammaglobulinemia↗

PubMed1976

Specific immunological test for the rapid identification of members of the genus Histoplasma.

A sensitive and specific immunological method was developed for rapid identification of the mycelial forms of Histoplasma capsulatum var. capsulatum, H. capsulatum var. duboisii, and H. farciminosum and for separation of these pathogenic fungi from morphologically similar hyphomycetes and other fungal pathogens. This method is based on the fact that all of the Histoplasma spp. produce H and M histoplasmin antigens, whereas the other fungi do not. Inocula consisting of heavy mycelial growth from a pure, full-grown culture were transferred into flasks containing small volumes of brain heart infusion broth. These cultures were placed on a shaker and grown at 25 C. Using the micro-immunodiffusion technique and antisera containing antibodies to H and M precipitinogens, we detected exoantigens in 3-day-old brain heart infusion culture supernatants concentrated 25 and 50 times. The ability of the procedure to identify Histoplasma spp. was evaluated by testing 96 unknown mycelial cultures that grossly or microscopically resembled Histoplasma spp. Three- and six-day-old concentrated culture supernatants prepared from each unknown were tested against rabbit anti-Arthroderma tuberculatum, Chrysosporium keratinophilum, H. capsulatum var. duboisii, and Corynascus (Thielavia) sepedonium sera and human histoplasmosis case serum. Each unknown was also identified by conventional laboratory procedures involving cultural and, where necessary, in vivo studies. In the comparative evaluation the immunological test was observed to be 100% sensitive. It permitted the accurate generic identification of the Histoplasma spp. within 5 days, in contrast to the average of 33 days required by the routine mycological procedure.

Antigens, Fungal↗

PubMed1978

Histoplasma meningitis with hyperactive suppressor T cells in cerebrospinal fluid.

Histoplasma meningitis usually occurs in conjunction with disseminated histoplasmosis. We studied a patient with common variable hypogammaglobulinemia who manifested meningitis without disseminated histoplasmosis. No histoplasma antibody was detected in cerebrospinal fluid (CSF) or blood. Evaluation of lymphocyte function in the blood revealed normal numbers of T cells with increased numbers of B cells. Most blood lymphocytes were identifiable, but most lymphocytes in CSF were null cells. Lymphocyte proliferative response to phytohemagglutinin or pokeweed mitogen was poor. T cells in CSF suppressed proliferative responses to histoplasma antigen by cells from blood or CSF, whereas T cells from blood did not. This difference suggested compartmentalization of T-cell function. The lack of humoral and cellular response to histoplasma in CSF may have allowed meningitis to develop, while the cellular response to histoplasma elsewhere prevented development of disseminated histoplasmosis.

Aged↗

PubMed1992

Comparative evaluation of a chemiluminescent DNA probe and an exoantigen test for rapid identification of Histoplasma capsulatum.

A chemiluminescent DNA probe (Accuprobe) assay developed by Gen Probe, Inc., for the rapid identification of Histoplasma capsulatum was evaluated and compared with the exoantigen test by using 162 coded cultures including Histoplasma capsulatum var. capsulatum, Histoplasma capsulatum var. duboisii, Histoplasma capsulatum var. farciminosum, Blastomyces dermatitidis, Coccidioides immitis, Paracoccidioides brasiliensis, and morphologically related saprobic fungi. Each test uses a chemiluminescent, acridinium ester-labeled, single-stranded DNA probe that is complementary to the rRNA of the target organism. Lysates of the test cultures were prepared by sonication with glass beads and heat treated. After the rRNA was released from the target organism, the labeled DNA probe combined with the target H. capsulatum rRNA to form a stable DNA-RNA hybrid. A hybridization protection assay was used, and the chemiluminescence of hybrids was measured initially with a Leader 1 luminometer as relative light units and later during the investigation with a probe assay luminometer as probe light units. Of the 162 coded mycelial cultures tested by the Accuprobe assay, 105 were identified as H. capsulatum. The test could be performed with an inoculum of a few square millimeters (1 to 2 mm2) of growth. In the primary evaluation, the Accuprobe identified 103 of the 105 cultures as H. capsulatum within 2 h. The remaining two cultures, contaminated with bacteria, had to be purified before the Accuprobe assay identified them correctly as H. capsulatum. Since each coded culture was concurrently tested for H. capsulatum, B. dermatitidis, and C. immitis exoantigens, the identification of all three dimorphic pathogens was provided simultaneously. Of the 162 coded cultures tested, 105 were identified by the exoantigen test as H. capsulatum, 12 were identified as B. dermatitidis, 13 were identified as C. immitis, and 32 were negative for H. capsulatum, B. dermatitidis, and C. immitis. The bacterial contamination in two isolates did not interfere with the exoantigen testing. The exoantigen test required 7- to 10-day-old colonies and required 48 to 72 h of incubation before definitive identification was obtained.

Antigens, Fungal↗

PubMed1991

Reevaluation of the teleomorph of the genus Histoplasma by ubiquinone systems.

Ubiquinone systems of the genus Histoplasma and Blastomyces dermatitidis were examined and the relationship between the two genera, Emmonsiella and Ajellomyces, was discussed. Ubiquinone systems have been adopted as a useful taxonomic criteria at the generic level for fungi. We investigated ubiquinone systems of sexual and asexual strains of Histoplasma species and Blastomyces dermatitidis. All the strains of the former group had dihydrogenated ubiquinone-10(Q-10(H2] as the major isoprenologue, while the latter had ubiquinone-10(Q-10). From the result, it was concluded that the teleomorph of Histoplasma species should be brought back to Emmonsiella.

Ascomycota↗

PubMed1985

Detection of an antigenic cell wall layer in Histoplasma capsulatum. An immunoelectron microscopic study.

Histoplasma capsulatum yeast cells have been studied by immunoelectron microscopy using rabbit polyclonal antisera and a biotin-avidin-peroxidase detection system. An antigenic surface layer has been visualized in the cell wall of immunostained organisms. This layer was not seen in samples prepared by standard electron microscopic methods or in negative controls used with the immunocytochemical technique. Without immunostaining the cell wall of Histoplasma appeared almost transparent. In contrast, after immunoperoxidase staining the cell wall was conspicuous, bounded by the darkly stained outer layer. This electron dense layer, appeared to be a reservoir of surface antigens that were recognized by anti-Histoplasma antibodies.

Animals↗

PubMed1991

Histoplasma capsulatum infection associated with continuous ambulatory peritoneal dialysis.

Fungal infection has become increasingly more important in patients undergoing continuous ambulatory peritoneal dialysis. We report here a case of Histoplasma capsulatum infection in such a Hong Kong Chinese patient who presented with fever and peritonitis. Histoplasma capsulatum was isolated from the dialysis fluid and histoplasma antibody was detected in the serum. The patient responded to the combined treatment of fluconazole, 5-flurocytosine and amphotericin B. This is the first reported case of histoplasmosis in Hong Kong.

Amphotericin B↗

PubMed2025

Expansion of secreted cystine knot proteins reveals virulence factors in the human fungal pathogen Histoplasma.

Identifying fungal secreted factors that influence host infection remains a key challenge in microbial pathogenesis. While secreted effectors, particularly small cysteine-rich proteins, are well characterized in plant fungal pathogens, their counterparts in mammalian pathogens are understudied. We apply criteria from plant fungal effectors to the mammalian fungal pathogen Histoplasma, yielding a set of putative effectors highly enriched for knottins, proteins that adopt a distinctive cystine knot fold. Using an algorithm, we further identify 25 putative knottins in the Histoplasma genome, revealing a significant expansion of knottin genes. Knottin domains are found in diverse molecules but play an unknown role in virulence. Functional studies of individual Histoplasma knottins demonstrate their critical roles in intracellular survival and host cell lysis during macrophage infection as well as virulence in vivo. These findings highlight the importance of knottins in fungal pathogenesis and suggest their broader relevance for discovering conserved mechanisms of host manipulation.

Histoplasma↗

PubMedDate not supplied

Ocular histoplasmosis due to Histoplasma farciminosum in Egyptian donkeys.

In this study 19 donkeys suffering from face excoriations below the medial canthas and lesions in the lacrymal apparatus were subjected to clinical radiological and microbiological investigations. Also histopathological examination of biopsy materials from ocular lesions were made. Eleven out of 19 donkeys (57.9%) showed specific lesions in the lacrymal apparatus. Mycological examination revealed the isolation of Histoplasma cells from 10 out of 19 examined cases. The isolated Histoplasma culture, although not completely identical to H. farciminosum, was more related to this than to other Histoplasma species. Histopathological examination revealed the presence of marked tissue infiltration by lymphocytes, monocytes and macrophages. Also the fungal organism appeared as double-contoured yeast cells lying within macrophages and giant cells.

Animals↗

PubMed1977

Adoptive transfer of immunity from mice immunized with ribosomes or live yeast cells of Histoplasma capsulatum.

This investigation was designed to compare the role of lymphoid cells and immune serum in protective immunity induced by immunization with ribosomes or live yeast cells of Histoplasma capsulatum. Spleen cells, peritoneal cells, and serum from C3H mice immunized with Histoplasma ribosomes or live cells were transferred intravenously to separate groups of syngeneic recipients. All recipients along with a set of immunized and control mice were challenged intravenously with 4 x 10(6) yeast cells of H. capsulatum, and protection was assessed. Immunization with ribosomes or live cells provided 90 to 100% protection. Mice receiving filtered spleen cells or peritoneal cells from donors immunnized with live cells showed 90 to 100% protection; 80 to 90% protection was observed for mice receiving cells from ribosome-immunized donors. In contrast, no evidence of protection was seen in mice receiving serum from either live-cell- or ribosome-immunized mice. Peritoneal cells were far more efficient than spleen cells in adoptive transfer of immunity. The adoptive immunity in recipients persisted for at least 3 weeks after transfer, the longest period tested in the present study. These results indicate that the immunity elicited by immunization with Histoplasma ribosomes or live cells is mediated by a cellular mechanism.

Animals↗

PubMed1986

Development and characterization of Histoplasma capsulatum-reactive murine T-cell lines and clones.

Experimental studies have suggested that antigen-specific T lymphocytes are important mediators of resistance to infection with the pathogenic fungus Histoplasma capsulation. To gain a better understanding of the role of T lymphocytes, we developed murine T-cell lines and clones that recognized Histoplasma antigens. These T cells were of the helper/inducer phenotype (Thy-1.2+ Lyt-1+ L3T4+ Lyt-2-) and exerted multiple immunological functions. T-cell lines and 12 clones proliferated vigorously in response to histoplasmin; the T-cell lines and 6 clones also were reactive with heterologous fungal antigens prepared from either Blastomyces dermatitidis or Coccidioides immitis. Recognition of antigen by T cells was H-2 restricted; in the absence of antigen, four clones demonstrated alloreactivity. All T-cell clones conferred local delayed-type hypersensitivity responses when injected with antigen into footpads of mice. Ten of 12 T-cell clones released interleukin-2 after stimulation with antigen, and all clones tested secreted interferon. Moreover, culture supernatants from antigen-stimulated clones armed peritoneal macrophages to inhibit intracellular growth of H. capsulatum yeast cells. All clones assayed exerted nonspecific help. Thus, development of T-cell clones should facilitate analysis of the regulatory properties of Histoplasma-specific T cells.

Animals↗

PubMed1989

Relative susceptibilities of inbred mouse strains C57BL/6 and A/J to infection with Histoplasma capsulatum.

Differences in the 30-day survival of Histoplasma capsulatum after intravenous injection indicated that the A/J strain of inbred mouse was more resistant to experimental infection than was the C57BL/6 strain. CFU from the spleens of infected animals increased during the first week after injection but gradually declined over the next 3 weeks. The CFU per gram of tissue in the C57BL/6 animals were 10- to 100-fold higher than were those in the A/J mice during the time between 7 and 28 days after infection. The units of gamma interferon (IFN-gamma) in supernatants of spleen cells stimulated with heat-killed yeast cells of H. capsulatum reached a peak at the time of the largest number of CFU per gram of tissue. The titers of IFN-gamma at days 3 to 5 were higher in the A/J mice than they were in the C57BL/6 mice, but from days 7 to 28, the titers of IFN-gamma were not correlated with the more efficient clearance of the fungus from the spleens of A/J mice. The L3T4+ spleen cells were shown to be active IFN-gamma producers. Treatment of Histoplasma-infected mice with anti-IFN-gamma antibody resulted in much larger tissue burdens of the fungus in the lungs and spleens of treated animals than in untreated animals. There was no marked difference in the result of treatment with anti-IFN-gamma antibody between A/J and C57BL/6 mice. Treatment of Histoplasma-infected mice with recombinant murine IFN-gamma did not alter the course of infection in either inbred strain of mouse.

Animals↗

PubMed1986

Evaluation of cross-reactions in Histoplasma capsulatum serologic tests.

Cross-reactivity in Histoplasma serologic tests was evaluated by using sera from patients with histoplasmosis and other infections. Serum samples from 127 of 134 (95%) patients with histoplasmosis were judged positive by complement fixation tests, and 121 (90%) showed H bands, M bands, or both by immunodiffusion. Of these 134 patients, cross-reactions were seen to Blastomyces dermatitidis in 53 patients (40%), to Coccidioides immitis in 20 patients (16%), and to Aspergillus fumigatus in 3 patients (2%) by complement fixation. Serum samples from 5 of 99 patients (5%) with other fungal infections and from 5 of 46 patients (11%) with tuberculosis had M precipitin bands by the Histoplasma immunodiffusion test, whereas none of the 123 sera from patients with other bacterial, Mycoplasma, or viral infections showed H or M precipitin bands. In the complement fixation test, positive reactions were observed in 16 of 90 patients (18%) with other fungal infections, in 14 of 41 patients (34%) with tuberculosis, and in 18 of 105 patients (17%) with other bacterial, Mycoplasma, or viral infections. Positive reactions were seen by radioimmunoassay in 54 of 110 patients (49%) with other fungal infections, in 23 of 46 patients (50%) with tuberculosis, and in 35 of 123 patients (28%) with with other bacterial, Mycoplasma, or viral infections. These results demonstrate a wider range of cross-reactions in Histoplasma serology than has been previously recognized, and the cross-reactivity was greatest when observed by radioimmunoassay. Caution should be exercised in the interpretation of serologic data from patients with suspected fungal infections.

Antibodies, Fungal↗