Nutritional characters in Ramularia species

Groups of mice were neonatally thymectomized and treated with antithymocyte serum (ATS) prior to challenge infection with viable yeast phase (YP)Histoplasma capsulatum G-17M. Moderate leucocytosis and moderate lymphopenia were seen in immunodeficient animals after infection. Surviving immunodeficient mice exhibited low levels of migration, inhibition activity, while peritoneal exudate cells and spleen cells harvested from surviving infected and untreated normal mice showed significant migration inhibition in the presence of histoplasmin antigen.The LD₅₀ values for YP cells ofH. capsulatum were 1.1×10⁶ for normal untreated mice, 6.0×10⁵ for thymectomized mice, and 6.3×10⁵ for ATS-treated mice. Thymectomized mice that also received ATS treatment exhibited an LD₅₀ of 1.7×10⁵ and were 6.5 times more susceptible to infection then normal mice. Mice which were either thymectomized or treated with ATS were 1.7 times as susceptible as normal mice to infection withH. capsulatum. The criterion of susceptibility is a decrease in the LD₅₀ value.     

Serological and skin test cross-reactivity between Histoplasma capsulatum and Oidiodendron kalrai

Guinea pigs were infected with yeast cells ofHistoplasma capsulatum andOidiodendrom kalrai. They were skin tested 6 and 12 weeks post-infection with both homologous and heterologous antigens. There was almost complete skin test cross-reactivity between histoplasmin and oidiodendrin after 12 but not after 6 weeks. There were also strong serologic cross-reactions among 6 different anti-H. capsulatum hyperimmune sera and oidiodendrin. However, cross-reactions among anti-O. kalrai sera and histoplasmin could not be demonstrated.     

Additional studies of histoplasmin formation

Summary Culture filtrates of 20 strains ofHistoplasma capsulatum were studied to determine the effect of certain growth conditions on histoplasmin formation. The presence of histoplasmin was denoted by an antigenic titer of 1:4 or higher with the complement fixation test.The data indicated that, in addition to verifying that the strain used affected histoplasmin formation, the morphological condition of the inoculum was extremely important. It was found that most strains which converted readily to the yeast phase at 37° C produced histoplasmin poorly. Tests with different volumes of media also showed that 500 ml volumes of culture media produced histoplasmin with higher titers than 3 liter volumes when cultured at 25° C for six months.Some additional histoplasmin could be liberated by sonification of the mycelial pad from culture filtrates which contained histoplasmin. A few strains produced high titer histoplasmin by the shake method if incubated for three months, but they had low titers after only six weeks.Complement fixation tests with sera from proven cases of histoplasmosis indicated that histoplasmin from a single strain ofH. capsulatum can give identical results with those obtained with histoplasmin from a pool ofH. capsulatum strains if H and M antigen components are present.     

In situ localization of antigens of Histoplasma capsulatum using colloidal gold immune electron microscopy

Histoplasma capsulatum contains multiple antigens, among them the H antigen and M antigen, which are useful in serologic testing for histoplasmosis. We prepared 7 mouse monoclonal antibodies (5 IgG, 2 IgM) to histoplasmin, and compared these with polyclonal histoplasmin antibodies raised in rabbits and mice. Both monoclonal and polyclonal antibodies were high titered by ELISA. Colloidal gold immune electron microscopy (CGIEM) showed that polyclonal antibodies to histoplasmin or H antigen bound at multiple sites in the cell wall, cytoplasm, and nucleus of Histoplasma yeast cells. In contrast, antibodies to M antigen selectively label the cell membrane and antibodies to alkali soluble cell wall antigen label only the cell wall. Polyclonal antibodies cross reacted extensively with other fungi, both by ELISA and CGIEM. Monoclonal antibodies stained only cytoplasmic epitopes, but also cross reacted with other fungi by electron microscopy. Only periodate treated H antigen elicited polyclonal antibodies which were more specific than those of untreated H antigen or histoplasmin.     

Cross-protection between Histoplasma capsulatum and Oidiodendron kalrai in mice

Summary Cross-protection studies were carried out by immunizing mice intraperitoneally with live and formalin killed yeast cells ofHistoplasma capsulatum andOidiodendron kalrai. Immunized and non-immunized mice were challenged intravenously 21 days later with the yeast cells ofHistoplasma capsulatum. The greatest protection was observed in mice immunized with live cells ofH. capsulatum and was definitely superior to that obtained with killed cells ofH. capsulatum. Significant protection against challenge byH. capsulatum was observed in mice immunized with killed but not with live cells ofO. kalrai.This work was supported from a research grant from the Bremer Foundation.The authors wish to thank Professor CharlotteC. Campbell for the supply ofHistoplasma capsulatum culture.     

Migration inhibition factor study in Histoplasma capsulatum

Mice sublethally infected with viable Histoplasma capsulatum or immunized with merthiolate-killed yeast phase cells showed decreased mortality on subsequent challenge infection as compared to controls. Migration inhibition (MI) assays using peritoneal and spleen cells from immunized but unchallenged mice showed no parallel correlation with percent mortality. MI assay indices fluctuated without concomitant changes in resistance to challenge injection with live yeast phase cells. Viable vaccines induced greater resistance to challenge infection than killed cells, although both were comparable in sensitizing ability as measured by MI assay techniques with this mouse model.     

Media matters! Alterations in the loading and release of Histoplasma capsulatum extracellular vesicles in response to different nutritional milieus

Histoplasma capsulatum is a dimorphic fungus that most frequently causes pneumonia, but can also disseminate and proliferate in diverse tissues. Histoplasma capsulatum has a complex secretion system that mediates the release of macromolecule‐degrading enzymes and virulence factors. The formation and release of extracellular vesicles (EVs) are an important mechanism for non‐conventional secretion in both ascomycetes and basidiomycetes. Histoplasma capsulatum EVs contain diverse proteins associated with virulence and are immunologically active. Despite the growing knowledge of EVs from H. capsulatum and other pathogenic fungi, the extent that changes in the environment impact the sorting of organic molecules in EVs has not been investigated. In this study, we cultivated H. capsulatum with distinct culture media to investigate the potential plasticity in EV loading in response to differences in nutrition. Our findings reveal that nutrition plays an important role in EV loading and formation, which may translate into differences in biological activities of these fungi in various fluids and tissues.     

Respiratory infection of mice with Histoplasma capsulatum

Summary Mice were infected by exposure to varying doses ofHistoplasma capsulatum yeast cells in the Henderson aerosol apparatus.Ten per cent of the animals were infected by inhalation of only 5 yeast cells. In the larger dosages used, 5, 400 to 24, 200 cells per animal, 90 to 100% infections were obtained. The disease spread rapidly from the lungs to the liver and spleen, with the liver generally containing the largest number of yeast cells. With small numbers of cells inhaled, mice were more highly positive at 4 weeks after exposure. In larger doses, per cent positive was highest at 2–4 weeks and mice sacrificed at later periods were less likely to yield as many positive animals.Presented in part at the annual meeting of the American Society for Microbiology, 1962.Work reported in this paper was supported in part by Grant E 1992 of the National Institutes of Health, U.S. Public Health Service.     

Immunomodulation by Histoplasma capsulatum products; polyclonal activation and mitogenic effects

The presence of reactive spleen cells to sheep red blood cells (SRBC) in nonimmunized BALB/c mice injected with histoplasmin, the culture filtrate of Histoplasma capsulatum, was monitored for 21 days following inoculation. Polyclonal activation, as evidenced by a sharp increase in the number of anti-SRBC rosetteforming cells (RFC), as well as an enhanced response to heterologous non-cross-reactive erythrocytes from other species, was found in the spleens of these rodents on Days 11 to 13. Elimination of B-cell-derived RFC by the addition of complement indicated that the erythrocyte-binding cells consisted of both T- and B-lymphocytes. An immunosuppressive effect was detected if histoplasmin was injected 2 days before the antigen (SRBC), but could be reversed by injecting the filtrate 30 min prior to the antigen, as is found with polyclonal activators displaying immunosuppressive activity. Histoplasmin also had a mitogenic effect on lymphocyte obtained from the spleen, bone marrow, and thymus similar in magnitude to that produced by lipopolysaccharide (LPS) and concanaval in A. The biological significance of these findings is discussed.     

Experimental histoplasmosis capsulati in athymic nude mice

Granuloma formation in nude (nu/nu) mice and their heterozygous littermates (nu/+ mice) against Histoplasma capsulatum var. capsulatum infection was studied.A culture of H. capsulatum var. capsulatum, isolated from a granuloma in the nasal cavity of a Japanese patient, was used in this experiment. Sixteen specific-pathogen-free male nu/nu and 32 nu/+ mice were used in this study.The nu/+ mice were divided into two groups. Sixteen nu/+ mice in one group and 16 nu/nu mice were inoculated intraperitoneally with 10⁶ yeast cells of the fungus, those in the other group of nu/+ mice were inoculated intravenously with the same number of the yeast cells. Two mice out of each group were sacrificed 2, 3, 7, 11, 14, 18, 25 and 30 days after inoculation, and each of their organs was examined histopathologically. In addition, pieces of these tissues were cultured on Sabouraud's dextrose agar slants.In the nu/+ mice inoculated intraperitoneally, although the fungus was recovered from the spleen, kidney and lymph nodes during the initial course of the infection, lesions were not detected in their histopathological sections. In the nu/+ mice inoculated intravenously, colonies were recovered from all of the organs examined, other than the brain and thymus, 7 days after inoculation.Histopathologically, a few microfoci consisting chiefly of mononuclear cells with or without yeast cells were found in the liver sections 4 days after inoculation. Seven and 11 days after inoculation the number of lesions had increased. They had large accumulations of mononuclear cells. From day 14 on, almost all of the yeast cells had lost most of their staining affinity or were destroyed in the granuloma. From day 25 on, the granulomatous lesions changed gradually to fibrous tissue.In the nu/nu mice the fungus was readily recovered from the spleen, liver, kidney and lymph nodes. Histopathologically, a few microfoci consisting of mononuclear cells were present in the liver sections 4 days after inoculation. That is to say, during the initial course of infection granulomas were formed. In the liver, from day 7 on, the lesions were large and their number increased. However, there was a definite difference between the nu/nu and nu/+ mice. In the former, the yeast cells were not killed, and they continued to multiply within the granulomas. These granulomas were never transformed into fibrous tissue.     

Immunocytochemical staining of Histoplasma capsulatum at the electron microscopic level

Summary Rabbits were immunized with histoplasmin emulsified in Freund's complete adjuvant. Antibody raised in these rabbits was exposed to Histoplasma capsulatum yeast cells, either in tissue culture medium, or after in vitro or in vivo phagocytosis by mouse macrophages. The sites of antibody binding were identified using an immunoperoxidase technique. At least two sites of antibody binding were identified, one to the fungal cell wall and the other to the outer cell membrane. Within 6 h after phagocytosis by macrophages, fungal cell walls appeared roughened, with what appeared to be cell wall antigen released into the phagolysosome, appearing associated with the phagolysosome membrane, and possibly adjacent macrophage cytoplasm. Similar staining of fungal antigen was noted in alveolar macrophages which had ingested Histoplasma capsulatum after a respiratory challenge. This method may be useful in detailing the host/pathogen interactions which occur in human pulmonary histoplasmosis.     

Immunology of histoplasmosis: Humoral and cellular activity from a polysacchari-de-protein complex and its deproteinized fraction in experimentally immunized mice

In a previous publication it was reported that a polysaccharide-protein complex (PPC), sensitive to -glucosidase, was isolated from Histoplasma capsulatum. This complex was strongly reactive in an agar gel diffusion assay with sera from patients with histoplasmosis, but was unreactive with sera from patients with coccidioidomycosis. Here, the studies with human sera have been expanded and attempts were made to determine the response of mice immunized with nonviable H. capsulatum or Cocccidioides immitis to PPC or its deproteinized fraction (D-PPC) using more sensitive tests for antibody and including also test for cell-mediated immunity. Histoplasmin and coccidioidin were compared with PPC or its deproteinized fraction (D-PPC) in all assays. In a counterimmunoelectrophoresis (CIE) assay, PPC and D-PPC reacted only with sera from patients with histoplasmosis, whereas cross reactions were noted with histoplasmin and coccidioidin using heterologous sera. Cross-reaction were observed with all four antigen preparations and both types of antisera using a micro complement fixation assay. The assay for macrophage migration inhibitory factor (MIF) was also relatively nonspecific, in that inhibition occurred with cells from animals sensitized with Histoplasma or Coccidioides using both homologous and heterologous antigens. In the footpad assay, histoplasmin and coccidioidin were highly cross-reactive in animals sensitized with the heterologous fungus, but the PPC and D-PPC from H. capsulatum elicited significant reactions only in animals sensitized with Histoplasma.     

II. Evidence of the presence in yeast extract of substances which stimulate the growth of Histoplasma capsulatum and blastomyces dermatitidis similarly to that found in starling manure extract

Summary A medium consisting of agar plus yeast extract contained the necessary metabolites for rapid growth and sporulation ofHistoplasma capsulatum andBlastomyces dermatitidis. H. capsulatum when harvested after 10 or 30 days incubation period from this medium was shown to have a similar number of spores as well as total particle viability for each period of growth.The growth characteristics ofH. capsulatum and four different isolates ofB. dermatitidis on yeast extract medium were similar to that obtained previously using starling (Sturnis vulgaris) manure extract medium. These characteristics are rapid growth consisting of many viable spores and a low ratio of vegetative mycelium.Several isolations ofH. capsulatum from naturally contaminated soil specimens were made using yeast extract medium.From the Communicable Disease Center, Public Health Service, U. S. Department of Health, Education, and Welfare.     

Histoplasmosis in northwestern Argentina II: Prevalence ofHistoplasmosis capsulati and Paracoccidioidomycosis in the population south of Chuscha,Gonzalo and Potrero in the province of Tucuman

The present work was undertaken to obtain epidemiological data on the extent and distribution ofHistoplasma capsulatum var.capsulatum andParacoccidiodes brasiliensis infections south of the Chuscha, Gonzalo and Potrero areas of Argentina. Skin tests surveys of the human population with histoplasmin and paracoccidioidin were carried out in the permanent population of those localities. The infection index of the population showed that the area south of Chuscha has a high-prevalence of histoplasmosis capsulati. The Gonzalo and Potrero areas, according to their rates of infection also can be considered to have a relatively high prevalence of this disease. The frequency of individuals infected withP. brasiliensis suggests that the level of exposure to this fungus is considerable, especially in Gonzalo where the frequency of infection was 9.23%. The endemic areas of both diseases can be superimposed, as occurs in the northeastern part of Argentina.     

Adherence Patterns of <Emphasis Type="Italic">Histoplasma capsulatum</Emphasis> Yeasts to Bat Tissue Sections

The adherence of Histoplasma capsulatum yeasts to lung, spleen, liver, gut, and trachea cryosections of Artibeus hirsutus bats and inbred BALB/c mice (control) was studied after in vitro yeast-tissue incubations. Candida albicans yeasts were used as a well-known adherent fungal model in the mice host, and latex beads were used as a negative adherence control. Adhered yeast cells were identified by using crystal violet staining and the immunoperoxidase method with specific antibodies. H. capsulatum yeasts adhered to all tissues tested, mainly in the lung. Moreover, H. capsulatum yeasts adhered preferentially to white and red spleen pulp, in contrast to the dispersed distribution of C. albicans yeasts. H. capsulatum yeasts were mostly found on the sinusoidal face of hepatocytes. In general, the gut showed a higher number of adhered H. capsulatum yeasts than the trachea in both bats and mice. H. capsulatum and C. albicans yeasts developed high selectivity for the lamina propria of the gut. In addition, H. capsulatum yeasts interacted better with the lamina propria and adventitia of the trachea. The number of H. capsulatum yeast cells that adhered to each tissue section type was always greater than the corresponding number of C. albicans yeast cells, and latex beads never adhered to the tissue sections. Controls with anti-H. capsulatum and normal rabbit sera showed a significant blockage of H. capsulatum yeast adherence to lung tissue. This is the first study describing the patterns of H. capsulatum yeast adherence to different bat and mouse tissues.     

A natural focus ofHistoplasma capsulatum var.duboisii is a bat cave

The natural reservoir ofHistoplasma capsulatum var.duboisii, the etiological agent of histoplasmosis duboisii (African histoplasmosis) is not yet known. We report the isolation ofH. 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 yieldedH. capsulatum var.duboisii. Of the 35 bats belonging to the speciesNycteris hispida andTadirida pumila examined, only one (N. hispida) yielded this fungus from its intestinal contents. Identification of the isolates asHistoplasma was confirmed by exoantigen tests and by mating with tester strains ofH. capsulatum. In vitro conversion to large yeast from suggestive ofH. 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 µm in diameter) within giant cells in the infected tissues. Investigations on the possible occurrence of human infections in the area are in progress.A poster based on this work was presented at the 11th ISHAM Congress in Montreal, Canada (22–28 June 1991), La-Hoffman Roche, Basel, Switzerland kindly financed the trip of one of us (H.C.G) for the Congress.     

Comparative fluorescent antibody staining of histoplasma capsulatum and histoplasma duboisii with a specific anti-yeast phase H. Capsulatum conjugate

Summary The specific anti-yeast phaseHistoplasma capsulatum conjugate has been tested against 13 yeast phase strains ofH. capsulatum and 9 ofH. duboisii. The conjugate was specific forH. capsulatum, no yeast phase form ofH. duboisii obtained in vitro or in vivo reacted with it. The taxonomic implications of these results are discussed.     

Incidence of histoplasmin hypersensitivity in the Philippines

Long-term residents of the Philippines were skin tested with histoplasmin skin test material. This study was conducted with 143 electric company (MERALCO) employees from Manila, Philippines. We found that 37 (26 %) of the subjects were skin test positive. Characteristics of the positive group were: average age of 37 years; all except one were lifelong inhabitants of Metro Manila; 25 were male and 12 were female; one-half of the subjects reported extended contact with chickens. Despite these findings, histoplasmosis is considered to be a very rare disease in the Philippines. This survey indicates that Histoplasma capsulatum is sufficiently present in the Philippines to come in contact withone-fourth of the test population. This reinforces the hypothesis that histoplasmosis is present in the Philippines and is probably being misdiagnosed as granulomatous-inducing diseases such as tuberculosis, e.g., so-called “drug resistant” tuberculosis. We recommend larger surveys of this type and attempts to culture the etiologic agent from natural sources such as chicken and bat droppings. This revised version was published online in July 2006 with corrections to the Cover Date.     

Studies in histoplasmosis III. Cross reactions and characterization of histoplasma and blastomyces inhibitory factors

Summary The Histoplasma tissue inhibitory factor HIF has been demonstrated in tissues of hamsters and mice infected with four strains ofHistoplasma capsulatum. A similar HIF has been demonstrated in liver homogenates from hamsters infected withBlastomyces dermatitidis.High titer HIF completely inhibits growth of yeast cells. Lower relative proportions of HIF: yeast cells results in diminution in number of colonies and delay in initiation of growth.The Histoplasma and Blastomyces HIF show cross-inhibition with the heterologous yeast cells, but do not inhibit the respective mycelia from these organisms although HIF is adsorbed from the supernatant by both yeasts and mycelium.Histoplasma HIF adsorbs, without inhibiting growth, toCandida albicans, Cryptococcus neoformans, Bacillus subtilis andEscherichia coli.Because of the non-specific adsorption of HIF, it is probable that it may often be present in tissue but not demonstrable because bound and probable that production of an HIF in infectious diseases may be a general phenomenon.Supported by Public Health Service Grant No. 1-SO-IFR-05359-01.     

Two-dimensional immunoelectrophoresis of histoplasmin and a purified polysaccharide-protein antigen ofHistoplasma capsulatum

Crude histoplasmin and a polysaccharide-protein complex (PPC-histo) antigens obtained from culture filtrates ofHistoplasma capsulatum were analyzed by single and tandem two-dimensional immunoelectrophoresis (TD-IEP) using a rabbit hyperimmune anti-histoplasmin polyvalent serum. Single TD-IEP showed 14 arc precipitates for histoplasmin. Continuity of arcs 2, 6, and 7, and 9 and 10 was observed, suggesting a different polymeric configuration of the same antigen. This was also confirmed in tandem TD-IEP of histoplasmin with homologous (PPC-histo) and heterologous PPC's fromBlastomyces dermatitidis, Paracoccidioides brasiliensis andCoccidioides immitis. Tandem TD-IEP of histoplasmin and PPC-histo displayed a similar antigenic pattern to histoplasmin alone, being arcs 1 and 3 more evident and apparently present only in histoplasmin and PPC-histo. Tandem TD-IEP showed common antigens among the other heterologous fungal purified antigens, and seems useful to observe the multiplicity of antigens present in fungal preparations and to identify those precipitates (arcs 1 and 3) that are predominant in the purified preparation.