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PubMed1994

A natural focus of Histoplasma capsulatum var. duboisii is a bat cave.

The natural reservoir of Histoplasma capsulatum var. duboisii, the etiological agent of histoplasmosis duboisii (African histoplasmosis) is not yet known. We report the isolation of H. capsulatum var. duboisii from soil admixed with bat guano and from the intestinal contents of a bat in a sandstone cave in a rural area, Ogbunike in Anambra State of Nigeria. Eight of 45 samples of soil admixed with bat guano yielded H. capsulatum var. duboisii. Of the 35 bats belonging to the species Nycteris hispida and Tadirida pumila examined, only one (N. hispida) yielded this fungus from its intestinal contents. Identification of the isolates as Histoplasma was confirmed by exoantigen tests and by mating with tester strains of H. capsulatum. In vitro conversion to large yeast from suggestive of H. capsulatum var. duboisii was obtained on brain heart infusion agar supplemented with sheep blood and glutamine or cysteine. Pathogenicity tests with mice for all the isolates confirmed their identity by the demonstration of large yeast forms (8-15 microns in diameter) within giant cells in the infected tissues. Investigations on the possible occurrence of human infections in the area are in progress.

Animals↗
PubMed1979

Lymphocyte stimulation by yeast phase Histoplasma capsulatum in presumed ocular histoplasmosis syndrome.

We measured skin reactions serum antibody, and lymphocyte stimulation to Histoplasma antigens in a series of patients with presumed ocular histoplasmosis syndrome and in controls. The most sensitive test, lymphocyte stimulation to H. capsulatum sonicate, also correlated with severity of the disease. Lymphocyte stimulation to Histoplasma may be a useful adjunct to the monitoring of presumed ocular histoplasmosis syndrome.

Antibodies, Fungal↗
PubMed1993

Aberrant Histoplasma capsulatum. Confirmation of identity by a chemiluminescence-labeled DNA probe.

A cottony, light tan, filamentous fungus with pear-shaped microconidia and lacking tuberculated macroconidia was isolated from a bronchial lavage specimen. Subculture on several media at 37 degrees C failed to convert the fungus to a yeast form after several weeks; attempts at in vivo conversion in mice were also unsuccessful. Sera obtained several months apart showed M bands with Histoplasma capsulatum (HC) antigen by immunodiffusion and an increase in complement fixation titers with mycelial and yeast phase antigens of HC. Parallel identity was obtained on two occasions with exoantigen culture confirmation reagents for HC from Immuno-Mycologics as well as one of identity with Nolan reagents. Extracts from four Chrysosporium spp. strains had no identity reactions with HC with either kit. The fungus was identified as HC by the Accuprobe Histoplasma chemiluminescence-labeled DNA probe directed at ribosomal RNA, whereas all four Chrysosporium spp. isolates tested negative. DNA probes are a fast and accurate method to confirm the identity of aberrant fungal isolates.

Aged↗
PubMed1984

Histoplasma capsulatum in the eye.

The ocular pathologic findings in an immunosuppressed patient who died of disseminated histoplasmosis are described. Histoplasma capsulatum was found in large numbers within the endothelial cells of the choroid, in one area each of the ciliary body and trabecular meshwork. There was a minimal inflammatory response. No granulomas were noted. Previously reported cases of ocular histoplasmosis in immunosuppressed patients are similar in that, with one exception, granulomatous inflammation was not demonstrated. Thirteen eyes in which histoplasma organisms have been found in the eye are reviewed.

Adult↗
PubMed2000

Endogenous endophthalmitis caused by Histoplasma capsulatum var. capsulatum: a case report and literature review.

OBJECTIVE: We report the first case of clinically diagnosed endogenous endophthalmitis caused by Histoplasma capsulatum var. capsulatum in a patient with the acquired immune deficiency syndrome. DESIGN: Interventional case report and literature review. INTERVENTION: Pars plana vitrectomy and scleral buckling procedure in the left eye with intravenous and intravitreal amphotericin in both eyes. MAIN OUTCOME MEASURES: The clinical features, culture results, visual outcome, and complications were studied. RESULTS: This case demonstrates a bilateral endophthalmitis with severe subretinal exudation, choroidal granulomas, and intraretinal hemorrhage leading to exudative bilateral retinal detachments. Vitreous cultures grew H. capsulatum var. capsulatum. Treatment consisted of intravenous amphotericin, intravitreal amphotericin (both eyes), pars plana vitrectomy (left eye), and scleral buckling procedure (left eye) with resulting counting fingers vision (right eye) and 20/300 (left eye). Four cases of Histoplasma endophthalmitis have been reported previously, all of which had a documented history of disseminated histoplasmosis and resulted in enucleation. CONCLUSIONS: H. capsulatum should be considered a possible etiologic agent of endophthalmitis, especially in patients with a history of disseminated histoplasmosis and/or immune deficiency.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

Interaction of Histoplasma capsulatum yeasts with galactosylated surface molecules of murine macrophages.

BACKGROUND: Histoplasma capsulatum (H.c.) yeast-cell binding to glycosylated surface molecules of murine macrophages was studied using attachment inhibition assays with different carbohydrate-treated H.c. yeast cells and participation of galactose and its derivatives as main sugar inhibitor was always demonstrated. METHODS: Liposomes incorporated with macrophage membrane proteins (MMP) were constructed to test involvement of macrophage surface glycoprotein molecules in H.c. binding. Yeasts attachment to MMP liposomes was successfully evaluated by ELISA method. Afterward, inhibition of H.c. yeast-cell attachment to [1,2-3H(N)]-cholesterol-MMP liposomes was monitored by radioactivity counting of the yeast-liposome pellet centrifuged at 500 g for 30 min when yeasts were previously incubated with different sugars. Other inhibition attachment assays using light microscopy and modified ELISA adapted to peritoneal or alveolar macrophage monolayers were also performed to determine inhibition mediated by carbohydrates. In these assays, Candida albicans (C.a.) was used as control of another type of yeast containing a lectin-like molecule. RESULTS: Histoplasma capsulatum yeasts attachment to MMP liposomes showed important decrease of radioactive counts when treated with galactose and lactose molecules. Light microscopy and modified ELISA confirmed inhibition mediated by galactose and its derivatives either in peritoneal or alveolar macrophages, and beta-galactose was better recognized than its alpha-anomer. In contrast, C.a. attachment to peritoneal or alveolar macrophages was not markedly affected by galactose-derivative molecules. CONCLUSIONS: Results suggest presence of a lectin-like component in H.c. yeast cells and reveal involvement of galactosylated surface molecules of murine macrophages as specific-sugar (ligand) residues recognized by the fungal lectin.

Animals↗
PubMed2001

Cloning and analysis of mold-specific genes in the dimorphic fungus Histoplasma capsulatum.

A critical feature in the pathogenesis of the respiratory pathogen Histoplasma capsulatum is the conversion from the mold form (found in soil) to the yeast form in the lungs of the host. Little is known about the molecular biology of Histoplasma dimorphism. In particular, the possible roles of genes which are transcriptionally silent in yeast (i.e. mold-specific) have not been studied. We have produced a cDNA library highly enriched for mold-upregulated clones by fragmenting cDNA and removing yeast-specific and common sequences with a highly efficient enzyme degrading subtraction method. Screening of randomly selected clones identified cDNA fragments representing 16 different mold-upregulated genes. Because multiple cDNA fragments can be treated as alleles in a genetic screen, we were able to apply probability analysis to estimate the total number of mold-upregulated genes. We estimate that there are 27 upregulated genes; cDNA fragments of 16 have been isolated. Here we report the first isolation and analysis of cDNA from two mold-specific genes, MS8 (GenBank AF292398) and MS88 (GenBank AF357882). The MS8 transcript was very strongly expressed in mold but not detected on Northern blots with yeast RNA. The putative MS8 protein was predicted to be 21.3 kDa (203 aa), very rich in glutamine and glycine and had a calculated pI of 6.76. The MS88 transcript was weakly expressed in mold and not detected in yeast. The putative MS88 protein was predicted to be 22.5 kDa (219 aa) with a pI of 4.46. GenBank similarity searches revealed that the putative MS8 protein was similar to a glutamine-rich protein, of unknown function, from the fungus Colletotrichum gloeosporioides (GenBank U94186). No significant matches were found for the putative MS88 protein.

Amino Acid Sequence↗
PubMed1998

Histoplasma acquisition of calcium and expression of CBP1 during intracellular parasitism.

A highly adapted parasite of macrophages, the yeast phase of Histoplasma capsulatum, survives and proliferates within phagolysosomes, while the mycelial phase exists only as a saprophyte in the soil. We have shown previously that these two phases of Histoplasma differ in their calcium requirements for growth and in the production of a released calcium-binding protein (CBP). Cloning and sequencing the CBP1 gene revealed two introns, a putative signal peptide and potential calcium-binding sites. We also evaluated CBP1 expression by reverse transcription-polymerase chain reaction (RT-PCR) of yeasts grown in broth culture and within two host cell types, a macrophage-like cell line and respiratory epithelial cells. H. capsulatum yeasts expressed CBP1 in all of these settings. Splenocytes from mice immunized with H. capsulatum yeasts responded to purified CBP in proliferation assays, providing evidence for the production of CBP during the infection of mammalian hosts. In addition, after H. capsulatum yeasts were subjected to a calcium-free shock, exogenously added CBP allowed yeasts to incorporate more calcium than yeasts incubated without added CBP. These results suggest that CBP may function to provide yeasts with calcium when they are in a low-calcium environment, such as the phagolysosomal compartment within macrophages.

Amino Acid Sequence↗
PubMed2000

Antibodies to antigens of Histoplasma, Blastomyces and Candida in HIV patients and carriers in Nigeria.

Serum samples from 60 subjects with confirmed HIV-1 infection including 28 AIDS patients and 32 carriers were examined by immunodiffusion for precipitating antibodies to antigens of Histoplasma, Blastomyces and Candida. Seven of the subjects, four patients and three carriers, showed antibodies to histoplasmin prepared from mycelial cultural filtrate of Histoplasma capsulatum var. capsulatum and H. capsulatum var. duboisii although without any clinical signs of classical or African histoplasmosis. Another eight subjects comprising five patients and three carriers demonstrated antibodies to yeast cell antigen of Candida albicans; three of the patients had oral lesions clinically suggestive of Candida infection. None of the serum samples revealed antibodies to "A" antigen (yeast cell antigen) of Blastomyces dermatitidis.

AIDS-Related Opportunistic Infections↗
PubMed1984

Evaluation of commercial reagents to identify the exoantigens of Blastomyces dermatitidis, Coccidioides immitis, and Histoplasma species cultures.

Commercially available individual serologic reagents (Nolan/Scott Biological Laboratories, Inc.) and an "exoantigen identification system" (a kit supplied by Immuno-Mycologics, Inc.) were evaluated at two laboratories for their possible application in the microimmunodiffusion test to identify Blastomyces dermatitidis, Coccidioides immitis, and Histoplasma species. Both laboratories accurately identified all the cultures, and comparison of the results obtained with the commercial products and those established with the conventional methods performed by a third control laboratory demonstrated full agreement. The use of these two commercial products is recommended for the immunologic identification of cultures suspected of being B. dermatitidis, C. immitis, and Histoplasma species. It was observed, however, that the exoantigen reactions for four B. dermatitidis and two C. immitis isolates were much sharper and more readable with the individual reagents than the reactions observed with the kit.

Antigens, Fungal↗
PubMed1978

Significance of thymus-derived lymphocytes in immunity elicited by immunization with ribosomes or live yeast cells of Histoplasma capsulatum.

The lymphoid cells responsible for protective immunity to histoplasmosis were characterized. Adoptive transfer of spleen and peritoneal cells treated with antiserum to theta-antigen from mice immunized with ribosomes or live yeast cells of Histoplasma capsulatum abrogated the ability of these cells to protect the syngeneic recipients, whereas treatment of lymphoid cells with antiserum to IgG did not affect the immunity. Prior removal of glass-adhering cells from spleen and peritoneal cell suspensions did not alter their protective activity. Treatment with mitomycin C, an antimitotic agent, ablated the capacity of immune lymphocytes to protect the syngeneic recipients. These results indicate that the immune spleen and peritoneal cells that confer immunity to histoplasmosis are thymus-dependent (T) lymphocytes and that their active proliferation in the recipients is necessary for expression of the protective immunity. Furthermore, the immunity elicited by immunization with histoplasma ribosomes and live yeast cells is mediated by a similar mechanism.

Adhesiveness↗
PubMed2000

Clinical prediction model for differentiation of disseminated Histoplasma capsulatum and Mycobacterium avium complex infections in febrile patients with AIDS.

BACKGROUND: Disseminated infection with Histoplasma capsulatum and Mycobacterium avium complex (MAC) in patients with AIDS are frequently difficult to distinguish clinically. METHODS: We retrospectively compared demographic information, other opportunistic infections, medications, symptoms, physical examination findings and laboratory parameters at the time of hospital presentation for 32 patients with culture documented disseminated histoplasmosis and 58 patients with disseminated MAC infection. RESULTS: Positive predictors of histoplasma infection by univariate analysis included lactate dehydrogenase level, white blood cell (WBC) count, platelet count, alkaline phosphatase level, and CD4 cell count. By multivariate logistic regression analysis, those characteristics that remained significant included a lactate dehydrogenase value > or =500 U/L (risk ratio [RR], 42; 95% confidence interval [CI], 18.53-97.5; p < .001), alkaline phosphatase < or =300 U/L (RR, 9.35; 95% CI, 2.61-33.48; p = .008), WBC < or =4.5 x 10(6)/L (RR, 21.29; 95% CI, 6.79-66.75; p = .008), and CD4 cell count (RR, 0.958; 95% CI, 0.946-0.971; p = .001). CONCLUSIONS: A predictive model for distinguishing disseminated histoplasmosis from MAC infection was developed using lactate dehydrogenase and alkaline phosphatase levels as well as WBC count. This model had a sensitivity of 83%, a specificity of 91%, and a misclassification rate of 13%.

AIDS-Related Opportunistic Infections↗
PubMed2004

Fosmid-based physical mapping of the Histoplasma capsulatum genome.

A fosmid library representing 10-fold coverage of the Histoplasma capsulatum G217B genome was used to construct a restriction-based physical map. The data obtained from three restriction endonuclease fingerprints, generated from each clone using BamHI, HindIII, and PstI endonucleases, were combined and used in FPC for automatic and manual contig assembly builds. Concomitantly, a whole-genome shotgun (WGS) sequencing of paired-end reads from plasmids and fosmids were assembled with PCAP, providing a predicted genome size of up to 43.5 Mbp and 17% repetitive DNA. Fosmid paired-end sequences in the WGS assembly provide anchoring information to the physical map and result in joining of existing physical map contigs into 84 clusters containing 9551 fosmid clones. Here, we detail mapping the Histoplasma capsulatum genome comprehensively in fosmids, resulting in an efficient paradigm for de novo sequencing that uses a map-assisted whole genome shotgun approach.

Contig Mapping↗
PubMed2004

False-positive Histoplasma antigenemia caused by antithymocyte globulin antibodies.

False-positive Histoplasma antigen results were identified in two patients who received rabbit antithymocyte globulin (ATG, Thymoglobulin(R)) to prevent allograft rejection. To determine the prevalence of false-positive results following the administration of Thymoglobulin, sequential specimens were tested from a cohort of transplant recipients. Of 107 such patients, 17 (15.9%) demonstrated false-positive tests for Histoplasma antigenemia. False antigenemia peaked at 2-4 weeks after ATG administration and cleared over the next few months. Physicians should be aware of the potential for false-positive results in specimens from patients who have received ATG.

Animals↗
PubMedDate not supplied

Comparative evaluation of the Premier enzyme immunoassay, micro-immunodiffusion and complement fixation tests for the detection of Histoplasma capsulatum var. capsulatum antibodies.

A total of 178 sera, including 68 from proven cases of histoplasmosis (65 positive for the presence of Histoplasma capsulatum var. capsulatum antibodies and three positive for antigen), 93 from patients with suspected histoplasmosis but with no laboratory evidence of H. capsulatum var. capsulatum infection, 14 from humans with heterologous fungal and non-fungal infections and three from normal individuals, were tested for IgG H. capsulatum antibodies and M or M and H precipitins by enzyme immunoassay (EIA) (Meridian Diagnostics, Cincinnati, OH, USA) and microimmunodiffusion (MID) respectively. Sixty-three of the 68 histoplasmosis case sera demonstrated IgG antibody, and 65 of 68 demonstrated the presence of specific precipitins in the MID test. Nine positive case sera, when tested with the Laboratory Branch complement fixation (LBCF) test, reacted positively to whole yeast and histoplasmin antigens (titres 1:8 to 1:512). Three histoplasmosis case sera repeatedly tested negative for IgG, specific precipitins and complement-fixing antibodies, whereas they were positive for Histoplasma antigen. Eighteen of 95 sera from patients without evidence of histoplasmosis demonstrated IgG antibody in the EIA only. Among these positive sera, three out of three cases of aspergillosis and three out of five cases of blastomycosis were confirmed. Sera from HIV-infected and healthy individuals did not show IgG or M and/or H antibodies to H. capsulatum. Ninety-three sera were negative by both EIA and MID. The EIA for IgG was less sensitive (97%) than MID (100%). The specificity of EIA and MID was 84% and 100% respectively.

Antibodies, Fungal↗
PubMed1986

Irreversible block of the mycelial-to-yeast phase transition of Histoplasma capsulatum.

p-Chloromercuriphenylsulfonic acid (PCMS), a sulfhydryl inhibitor, prevented the mycelial-to-yeast transition of the dimorphic fungal pathogen, Histoplasma capsulatum. The effect of PCMS was specific for the mycelial-to-yeast transformation; it had no effect on growth of either the yeast or mycelial forms or on the yeast-to-mycelial transition. The failure of PCMS-treated mycelia to transform to yeast was permanent and irreversible. PCMS-treated mycelia could not infect mice but could stimulate resistance to infection by a pathogenic strain of Histoplasma capsulatum. These results suggest a new general strategy for vaccine development in diseases caused by dimorphic pathogens.

4-Chloromercuribenzenesulfonate↗
PubMed1967

Soluble antigens for immunofluorescence detection of Histoplasma capsulatum antibodies.

Soluble antigens from Histoplasma capsulatum in the mycelial and yeast phase were purified by gel filtration, fixed onto paper discs, and employed in an indirect immunofluorescence procedure to detect antibody in sera from individuals infected with H. capsulatum. The elution patterns of crude histoplasmin passed through Sephadex G-200 revealed two minor peaks of protein showing immunofluorescence, complement fixing, and precipitating-antigen activity. A large peak containing the pigment and other low molecular weight materials showed no serological activity. A polysaccharide antigen obtained from fragmented, deproteinized yeast-phase cells was reactive in the fluorescent-antibody test but showed no antigen activity in complement fixation or precipitin tests. Although certain sera from culturally proven cases of blastomycosis, coccidioidomycosis, and cryptococcosis reacted with the purified Histoplasma antigens, preliminary evaluation indicated that the immunofluorescence technique may be of value as a screening procedure for the serodiagnosis of histoplasmosis.

Antibodies↗
PubMed1977

Cell wall studies of Histoplasma capsulatum and Blastomyces dermatitidis using autologous and heterologous enzymes.

Enzymes capable of hydrolyzing cell walls of Blastomyces dermatitidis and chemotypes I and II of Histoplasma capsulatum were prepared in the laboratory or obtained from commercial sources. They included chitinases, beta-1,3-glucanases, beta-1,6-glucanase, and Pronase. Monosaccharides and disaccharides of glucose released from the cell walls by the enzymes were determined qualitatively by paper and gas-liquid chromatography, and monosaccharides were quantitated by the latter technique as well. An enzyme system isolated from Streptomyces sp. containing both chitinase and glucanase released maximum amounts of glucose and N-acetylglucosamine from the cell walls of H. capsulatum chemotype I. A chitinase preparation, free of glucanase, from Serratia marcescens released only chitobiose and N-acetylglucosamine from chemotype I cell walls, but the total quantity of N-acetylglucosamine released was about 60% less than that released by the Streptomyces system. A beta-1,3-glucanase from Bacillus circulans hydrolyzed the cell walls of H. capsulatum chemotype I, but a beta-1,6-glucanase failed to release glucose from the same walls. Autolytic enzymes, viz., beta-1,3-glucanases and several glycosidases were detected as constitutive enzymes in both yeast and mycelial phases of B. dermatitidis and H. capsulatum chemotypes I and II. No difference in the amount of activity was found between cell sap and culture filtrate preparations. The beta-glucanases prepared from the Histoplasma and Blastomyces strains were active on the cell walls of the yeast phases of H. capsulatum chemotypes I and II, releasing laminaribiose and glucose, but were essentially inactive on the cell walls of B. dermatitidis. Chitinase, beta-1,6-glucanase, alpha-glucanase, and alpha-glucosidase activities were absent from these fungal enzyme preparations.

Acetylglucosamine↗