Defensive role of granuloma againstSporothrix schenckii infection

The defensive role of granuloma againstSporothrix schenckii infection was studied histopathologically using nude(nu/ nu) and their heterozygous(nu/+) littermates.Three strains ofS. schenckii (Sp.-1, Sp-17 and Sp-56) were used in this experiment. Each mouse was inoculated into a tail vein with 10⁶ yeast cells of the Sp-1, Sp-17 or Sp-56. The mice were sacrificed at adequate intervals until the 30th day and histopathological sections were prepared from various organs.The numbers of lesions and yeast cells were counted using the liver sections. Furthermore, an experiment of lymph node cell transfer and immunological examinations were carried out.As results the susceptibility of mice to three strains were conspicuously different from each other. The Sp-1 showed the strongest pathogenicity and the Sp-56, the weakest. The susceptibility of the nu/ nu mice inoculated with the Sp-1 was much higher than that of the nu/+ mice and the difference was due to the killing functions of granuloma. Even though about two days' delay was observed in the granuloma formation in the nu/ nu mice in comparison with that in the nu/+ mice, these granulomata could not be distinguished from those of the nu/+ mice. However, functionally there was a definite difference between the granulomata formed in the nu/+ and nu/nu mice. Mononuclear cells forming the granulomata in the nu/ nu mice did not have the ability to kill the yeast cells they had engulfed. Cooperation with T-lymphocytes was necessary for the killing of the yeast cells. A significant response of MIF developed in the immunocompetent mice 11 days after inoculation of the Sp-56, and that day nearly coincided with the day when yeast cells of the Sp-1 began to be destroyed in the granulomata. It was also confirmed by the experiment of lymph node cell transfer that T-cell functions were indispensable for the killing of the yeast cells by mononuclear cells.From these results the authors hypothesize that the mononuclear cells activated with T-lymphocytes could play a leading role as the defense mechanism of mice againstS. schenckii infection.     

Defense mechanisms of mice against Fonsecaea pedrosoi infection

Defense mechanisms of a host against Fonsecaea pedrosoi infection were studied histopathologically using athymic nude (nu/nu) mice of BALB/c background and their heterozygous (nu/+) littermates. Thirty male nu/nu and 30 nu/+ mice, weighing 16–19 g, were employed in this experiment. The nu/nu or nu/+ mice were divided into 3 groups consisting of 10 each. Furthermore, 4 nu/nu mice were supplemented to investigate effects of lymph node cell transfer. Subglobose cells of F. pedrosoi Tsuchiya strain were obtained from a culture in brain heart infusion glucose (1%) broth with reciprocal shaking at 37 °C for 17 days, and then 0.02, 0.1 and 0.5% cells suspensions were prepared. Each cell suspension was allotted to one group of the nu/nu or nu/+ mice. 0.1 ml of the cell suspension was inoculated into a tail vein, then one mouse from each group was sacrificed 1, 2, 4, 6, 8, 10, 14, 18, 21 and 25 days after inoculation. In both the nu/nu and nu/+ mice, the brain, kidneys and heart were affected severely with the strain in that order. Histopathologically, the defense mechanisms of the nu/+ mice against the fungus infection consisted chiefly of 2 steps: first, of non-immune phagocytosis by polymorphonuclear leucocytes (PMNs), and second, of granuloma formation induced by cell-mediated immunity. Those of the nu/nu mice consisted only of one step: phagocytosis by PMNs. A difference in susceptibility to the strain between the nu/nu and nu/+ mice changed according to the amount of the fungal cells inoculated. When inoculated with the 0.02% cell suspension, the resistance of the nu/nu mice was stronger than that of the nu/+ mice. In contrast, when inoculated with the 0.5% cell suspension, the former was affected more severely than the latter. There were little differences in the susceptibility to the strain between the nu/nu and nu/+ mice inoculated with the 0.1% cell suspension. These data seem to indicate that the phagocytic function of PMNs of the nu/nu mice was more active than that of the nu/+ mice, and the nu/nu mice inoculated with the 0.5% cells suspension (beyond the phagocytic capacity) lost resistance against the fungus infection. When the nu/nu mice were transferred with lymph node cells before inoculation of the strain, granulomata were formed to prevent hyphae from growing freely in the tissue.     

Defensive role of granuloma againstSporothrix schenckii infection

The defensive role of granuloma againstSporothrix schenckii infection was studied histopathologically using nude(nu/nu) and their heterozygous(nu/+) littermates. Three strains ofS. schenckii (Sp.-1, Sp-17 and Sp-56) were used in this experiment. Each mouse was inoculated into a tail vein with 10⁶ yeast cells of the Sp-1, Sp-17 or Sp-56. The mice were sacrificed at adequate intervals until the 30th day and histopathological sections were prepared from various organs. The numbers of lesions and yeast cells were counted using the liver sections. Furthermore, an experiment of lymph node cell transfer and immunological examinations were carried out. As results the susceptibility of mice to three strains were conspicuously different from each other. The Sp-1 showed the strongest pathogenicity and the Sp-56, the weakest. The susceptibility of the nu/nu mice inoculated with the Sp-1 was much higher than that of the nu/+ mice and the difference was due to the killing functions of granuloma. Even though about two days’ delay was observed in the granuloma formation in the nu/nu mice in comparison with that in the nu/+ mice, these granulomata could not be distinguished from those of the nu/+ mice. However, functionally there was a definite difference between the granulomata formed in the nu/+ and nu/nu mice. Mononuclear cells forming the granulomata in the nu/nu mice did not have the ability to kill the yeast cells they had engulfed. Cooperation with T-lymphocytes was necessary for the killing of the yeast cells. A significant response of MIF developed in the immunocompetent mice 11 days after inoculation of the Sp-56, and that day nearly coincided with the day when yeast cells of the Sp-1 began to be destroyed in the granulomata. It was also confirmed by the experiment of lymph node cell transfer that T-cell functions were indispensable for the killing of the yeast cells by mononuclear cells. From these results the authors hypothesize that the mononuclear cells activated with T-lymphocytes could play a leading role as the defense mechanism of mice againstS. schenckii infection.     

Tissue responses against Cladosporium trichoides and its parasitic forms in congenitally athymic nude mice and their heterozygous littermates

The tissue responses against Cladosporium trichoides and its parasitic forms were studied using nude (nu/nu) mice and their heterozygous (nu/+) littermates of BALB/c background.1.0,0.1 and 0.01% cell suspensions were prepared from a culture broth which had been inoculated with the C. trichoides and cultured with reciprocal shaking at 27 ° C for 7 days. Sixty nu/nu or 60 nu/+ mice were divided into three groups consisting of 20 each which was allotted to one of the three cell suspensions. Each mouse was inoculated intravenously with 0.1 ml of either the cell suspensions. Two mice from each of the six groups were sacrificed at adequate intervals until 30 days after inoculation and histopathologic sections stained with H & E or by PAS were prepared from their visceral organs.There were no characteristic findings in the nu/nu and nu/+ mice inoculated with the 0.01% cell suspension. When inoculated with the 1.0% cell suspension, the brain was the favorite target organ in both groups of mice and the kidney was the second. When inoculated with the 0.1% cell suspension, brain lesions were observed only in the nu/nu mice. The susceptibility of the nu/nu mice was higher than that of the nu/+ mice.The parasitic forms in the brain of the nu/nu and nu/+ mice were slender septate true hyphae with or without polymorphonuclear leucocyte infiltrate, while in the liver, spleen and lung of both groups of mice the parasitic forms were short thick hyphae, moniliform hyphae, chlamydospores or round cells (sclerotic cells). Many giant cells containing fungal elements appeared in the liver of the nu/nu mice.     

Histopathological studies on experimental Cryptococcosis in nude mice

Cryptococcosis in nude (nu/nu) mice was examined histopathologically. In addition, effects of carrageenan and lymph node cell transfer againstCryptococcus infection were investigated. As controls, heterozygous littermates (nu/+mice) and mice of strain ddy (ddy mice) were employed.Each mouse was inoculated intravenously with 10⁵ yeast cells ofCryptococcus neoformans suspended in 0.2 ml phosphate-buffered saline. Two mice out of each group were sacrificed at appropriate intervals up to 25 days after inoculation and histopathological sections were prepared from them. They were stained with H & E and by PAS method. Histopathological characterristic in the brain was cyst formation with no cellular response. The brain was more severely in the nu/nu mice than in either the nu/+ or ddy mice. In the liver, there was a major difference in histopathological findings between the nu/nu and either of the other groups of mouse. In the nu/nu mice, cyst formation with no cellular response was induced, and on the contrary granuloma formation in the nu/+ and ddy mice. However, the granuloma formation was inhibited in the livers of the nu/+ and ddy mice by administration of carrageenan, and induced in the nu/nu mice by cell transfer. In the spleen and lymph nodes, lesions were severer in nu/nu mice than in either the nu/+ or ddy mice.These results suggested that the fungus' invasiveness of mice was strongly influenced by T-cell dependent mechanism.     

Induction of granuloma-dependent angiotensin-converting enzyme and eosinophil chemotactic factor in the skin of athymic nude mice

Activities of angiotensin-converting enzyme (ACE), other proteinases, and eosinophil chemotactic factor (ECF-G) are known to be elevated in hepatic hypersensitivity granulomas of thymus intact (nu/+) mice after Schistosoma mansoni infection. The enzyme activities also increase, but to a lesser degree in hepatic granulomas of athymic nude (nu/nu) mice, and ECF-G is not detectable. In this study isolated hepatic granulomas from nu/+ mice were grafted into the skin of uninfected nu/nu mice, and changes in those cellular functions were determined to examine whether the newly formed granulomas by recipient nu/nu cells acquire the functional activities as well as the histological appearance of nu/+ granulomas. ACE and ECF-G rapidly disappeared from grafted sites during the first 5 days, corresponding to loss of nu/+ cells from the graft. Reduction in activities of arylsulfatases, lysozyme, and acid phosphatase also occurred, but to a lesser extent. Recovery of ACE and ECF-G activities to the levels seen in nu/+ hepatic granulomas was observed by 14 days after grafting when nu/nu cells had accumulated in the grafts and formed new granulomas. Other enzymes increased to approximately half the levels seen in grafted donor granulomas. Circulating eosinophilia also increased. The findings indicate that nu/nu cells that accumulated in the skin grafts not only morphologically mimicked nu/+ type granulomas but also demonstrated nu/+ levels of cellular function. Analysis of skin granulomas developing in nu/+ mice after grafting of nu/+ hepatic granulomas showed the similar histology and enzymatic changes, whereas the skin sites inoculated with purified schistosome eggs alone caused neither significant histological changes nor elevation of ACE activity.     

Mycoplasma pulmonis Arthritis in Congenitally Athymic (Nude) Mice

Histopathological examinations were performed on arthritic joints and other organs of strain BALB/cA nu/nu and nu/+ mice intravenously injected with Mycoplasma pulmonis strain m53. In both groups of mice suffering from polyarthritis, acute inflammatory lesions with infiltration of polymorphonuclear leukocytes in the synovia and periarticular tissues were observed one to two weeks after injection. In nu/nu mice, the acute inflammation appeared repeatedly up to 20 weeks after inoculation, when the experiment was terminated, and furthermore, extensive synovial and periarticular necrosis were characteristically present after the 4th week. Only a small number of lymphocytes and plasma cells were in the lesions. In nu/+ mice, after the early acute inflammation of arthritis, relapses of the infiltration of polymorphonuclear leukocytes were also observed in some mice in and after the 10th week. In addition, infiltration of lymphocytes and plasma cells was substantial after the 15th week. Focal necrosis was sometimes found in the liver of nu/nu mice. Perivascular infiltration of small lymphocytes and plasma cells was found in the lungs, liver and kidney of nu/+ mice in and after the 15th week. Repair mechanisms of injured articular tissues in nu/nu mice were histopathologically poor, while those in nu/+ mice seemed to be progressive and quite similar to those reported by many investigators for mice with the thymus intact. The histopathological differences are discussed in respect to the thymus-dependent immune responses.     

Paracoccidioidomycosis in nude mice: Presence of filamentous forms of the fungus

Congenitally athymic nude mice (nu/nu) and their phenotypically normal littermates (nu/+) were intraperitoneally infected with yeast cells of a strain of Paracoccidioides brasiliensis. The nude mice developed a severe and generalized infection with an intense parasitism of several organs, accompanied by a low-grade of tissue reaction. The lesions were characterized by abundant yeast-like cells of the fungus, and in some animals, numerous hyphal forms could be well visualized. In control animals, infection was moderate, almost exclusively restricted to the area of inoculation, and the lesions presented few parasites surrounded by an inflammatory response. Filamentous forms of the fungus were never encountered in these animals.     

Effect of immune heterozygous spleen cell transfer on resistance to mouse hepatitis virus infection in nude mice

The role of cell mediated immune response to mouse hepatitis virus (MHV) infection in mice was studied by transferring spleen cells from immune heterozygous littermates (nu/+). A suppressive effect on viral growth was seen in infected nude (nu/nu) mice, whereas immune nu/+ serum transfer had no effect. The protective effect of immune nu/+ spleen cells was significantly reduced by treatment with anti-theta serum plus complement but not with anti-Ig serum. In infected nu/nu mice which received transfers of immune nu/+ cells, neutralizing antibody appeared although the titer was not high enough to protect nu/nu mice from fatal infection. Histopathologically, lymphocyte infiltration in hepatic lesions was evident in infected nu/nu mice with nu/+ cell transfer, while it was slight without nu/+ cell transfer.     

Transfer of granulomatous inflammation with nonviable preparations of schistosome granulomas in naive mice

Hepatic granulomas of euthymic (nu/+) mice infected with Schistosoma mansoni were freeze-dried or freeze-thawed 3 times and transplanted subcutaneously into naive nu/+ and athymic (nu/nu) mice. The grafted sites, studied histologically, showed formation of organized granulomas in nu/+ mice similar to donor granulomas as observed after grafting of freshly isolated granulomas. On the other hand, in nu/nu mice, the nonviable transplants elicited small and disorganized granulomas, like hepatic granulomas in nu/nu mice with schistosomiasis, but different from fresh nu/+ transplants in nu/nu skin. The findings indicate viable cells are not required for transfer of granulomatous reactions, but T cells are needed for full expression.     

Increased resistance of splenectomized mice to Sporothrix schenckii infection

The susceptibility of splenectomized mice to Sporothrix schenckii was studied, and the role of the spleen in the host defense is discussed. S. schenckii Sp-1 and ddy male mice were used. The mice were divided into 3 groups consisting of splenectomized, sham-operated and intact mice. Each mouse was inoculated intravenously with 2×10⁶ yeast cells 7 days after operation and the mice were sacrified at adequate intervals for 30 days. Then histological sections stained with H&E or by PAS were prepared from various visceral organs. Using the liver sections the number of yeast cells in a 40 mm² was counted. Furthermore, the colony forming unit in 100 mg of the liver tissue was compared to each other.In the sham-operated and intact mice many purulent lesions appeared on the 5th day. On the 8th day mononuclear cells accumulated at the foci, and on the 10th day most of the foci became granulomatous. The number of yeast cells in granulomatous lesions reached a peak on the 10th day and thereafter decreased abruptly. On the other hand, in the splenectomized mice approximately half of foci became granulomatous on the 5th day, and the number of yeast cells in the foci began to decrease after the 5th day.There were definite differences in the colony forming unit between the splenectomized and sham-operated or intact mice sacrificed 9 days after inoculation. The colony forming unit of the former is 9.3×10⁵ on the average, while that of the latter two is 5.6×10⁶ and 5.1×10⁶ on the average, respectively.In conclusion the resistance of ddy mice to S. Schenckii infection is enhanced due to splenectomy.     

Studies on relationship between cysts and granulomas in murine cryptococcosis

The histopathology of murine cryptococcosis was observed until the 55th day and particular attention was paid to whether or not cysts, which had been formed in the brain, could change to granulomas. Cryptococcus neoformans RIB-12M was used in this experiment. As experimental animals, five-week-old male BALB/c mice, weighing 20–22 g, were used. An infective inoculum was prepared by adjusting the number of cryptococci to 10⁶ or 5 × 10⁶/0.2 ml. Each mouse was inoculated intravenously with 0.2 ml of the cell suspension, and the colony forming unit of the brain and liver, and the histopathological findings in various visceral organs were investigated.40 × 10⁴ colonies grew from 100 mg of the brain tissue of the eighth day. Thereafter, the number increased gradually. It reached 500 × 10⁴ on the 20th day. The colony forming unit from the liver reached a peak on the 12th day (250 × 10⁴) and thereafter the number decreased gradually.Histopathologically, the brain and liver were severely affected with the fungus. In the brain cysts with cryptococci continued to increase until the end of the experiment. On the other hand, in the liver several purulent foci appeared on the second day. On the eighth day numerous mononuclear cells accumulated at the foci and their lesions changed to granulomatous ones with cryptococci. The number of granulomatous lesions reached a peak on the 16th day in the mice inoculated with 5 × 10⁶ cryptococci, and thereafter showed a tendency to decrease gradually.     

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.     

Cell-mediated immune responses in mice infected with fonsecaea pedrosoi

Time course of cellular and humoral immune responses in mice infected with Fonsecaea pedrosoi was investigated by using an antigen prepared from culture filtrate of this fungus. Mice were infected by intravenous injection with yeast-like cells of the fungus. Viable fungus was recovered from the brain of the infected mice until the 36th day after inoculation, and from the other organs examined until 14th to 16th day. Inflammatory lesions were observed in the brain, lung, heart, liver, spleen, kidney and intestine during the first 30 days after inoculation. Macrophage migration inhibition factor response in these mice was insignificant until 8 days after inoculation. A significant response was developed at day 10 and persisted until day 63. This response returned negative by 95 days after inoculation. Lymphocyte transformation response of these mice was negative until 4 days after inoculation. At day 6 blastogenic index increased to 1.5, and at day 10, 14 and 16 the indices were 1.8, 2.4 and 1.7 respectively. Precipitin response to this fungus could not be detected in these mice until 16 days after inoculation. Positive results were obtained at day 21 and lasted until 51 days after inoculation. The precipitin titers, however, did not exceed one fold in any of these mice.     

Decreased virulence in stable,acapsular mutants ofCryptococcus neoformans

Six acapsular strains ofCryptococcus neoformans obtained by chemical mutagenesis failed to produce a capsulein vivo and were avirulent in mice following high dose intramuscular, intraperitoneal or intravenous inoculation. Peritoneal granulomas were observed in all animals inoculated with the acapsular mutants. These granulomas were characterized by a large central mass consisting of intact, degenerating and necrotic yeast cells. This was surrounded by concentric layers of a broad band of histiocytes, a narrow band of fibroblasts, and around the periphery, a mass of lymphocytes and plasma cells. These isolates did not revert to an encapsulated or virulent state after more than a year of subculturing or 18 passages through mice.     

Role of L3T4+ and LyT-2+ cells in experimental visceral leishmaniasis

In contrast to euthymic (nu/+) BALB/c mice, athymic nude (nu/nu) BALB/c mice fail to control the visceral intracellular replication of Leishmania donovani, do not generate the macrophage-activating lymphokine IFN-gamma, and show little or no granulomatous tissue response. To characterize the T cell requirement for successful defense against L. donovani, nude mice were first reconstituted with unfractionated nu/+ immune spleen cells, which readily conferred the capacity to control and eliminate visceral (hepatic) L. donovani. In reconstituted mice, acquired resistance was paralleled by the ability of spleen cells to generate high levels of leishmanial Ag-stimulated IFN-gamma and the development of well formed liver granulomas. In contrast, nude mice reconstituted with either L3T4+- or Lyt-2+-enriched immune spleen cells alone failed to control visceral parasite replication and did not develop effective granulomas despite the finding that transfer of L3T4+ cells largely and Lyt-2+ cells partially restored the capacity to secrete IFN-gamma. To determine whether both T cell subsets were also required in a normal host, nu/+ BALB/c mice were treated with cell-depleting anti-L3T4 and anti-Lyt-2 mAb. Depletion of either T cell subset inhibited the acquisition of resistance to L. donovani and impaired the tissue granulomatous response. Thus, successful T cell-dependent host defense towards intracellular L. donovani and the tissue expression (granulomas) of this mechanism appear to require both L3T4+ and Lyt-2+ cells. A primary role for the L3T4+ cell may be IFN-gamma production; the role of the Lyt-2+ cell and the precise interaction of the two T cell subsets remain to be identified.     

Experimental histoplasmosis in temporarily „hibernating“ hamsters

Summary Although occasional hibernation was observed in golden hamsters kept at low temperatures during the winter months, the periods of hibernation were apparently too short to induce conversion of the yeast cells ofH. capsulatum into the mycelial phase or to prevent conversion into the yeast phase when inoculated in the mycelial phase.As a result of exposure to low temperatures, a heavily disseminated, severe and often fatal histoplasmosis was observed in contrast to slight dissemination in control animals kept at room temperature.In addition to extensive lesions in the organs in the heavily infected hamsters, severe fungemia, accumulations of numerous yeast cells within large cells and histoplasmic phlebitis and pleuritis of a proliferative character were seen.Schaumann bodies did not develop in granulomatous lesions of heavily infected animals kept at low temperatures, nor were they prominent in tissues with heavy accumulations of yeast cells or after inoculation with the mycelial phase.This project was supported in part by Grant E-576 from the National Institutes of Health.     

Sequential pathological studies in goats infected intratracheally withAspergillus fumigatus

Intratracheal inoculation of goats withAspergillus fumigatus spores resulted in the development of characteristic gross and microscopic lesions. The lesions were restricted to lungs and there was no dissemination of infection to other tissues of the body except liver in one goat 16 days after infection. The experiment was continued for 37 days. Gross changes in lungs were observed up to the 24th day post-infection. The lesions, in general, included congestion and oedema in the first 6 days followed by the development of varying greyish-white nodules in the lungs. Microscopic changes consisted of granulomatous reaction with well developed granulomas in lungs. Hyphae and conidiophores with fruiting bodies ofAspergillus fumigatus could be demonstrated in sections up to 24 days of infection. Reisolation of the fungus consistently was achieved up to 24 days. It is concluded that intratracheal inoculation ofAspergillus fumigatus spores in goats leads to pulmonary aspergillosis up to 24 days.     

Parasitism of monolayer cultures of dog tissue by Histoplasma capsulatum,I preliminary investigations

Summary Monolayer tissue cultures of canine kidney are demonstrated to by susceptible to invasion by yeast-phaseHistoplasma capsulatum. Primary and secondary tissue cultures of canine kidney show different levels of invasion by the pathogen at 24 hours after inoculation; these differences are interpreted as being related to the number of dividing host cells. By 72 hours after inoculation, similar numbers of yeast cells are demonstrable within the host cells of primary and secondary cultures. Essentially identical results were obtained when canine heart tissue cultures were inoculated with y-phaseH. capsulatum.Paper No.713, Department of Botany and Plant Pathology, The Ohio State University, 1735 Neil Avenue, Columbus 10, Ohio; correspondence should be directed to the junior author at the above address.     

Acute oral intragastric pathogenicity and toxicity in mice of <Emphasis Type="Italic">Paecilomyces fumosoroseus</Emphasis> isolated from whiteflies

Paecilomyces fumosoroseus, monospore culture EH-506/3, isolated in Mexico from Bemisia tabaci whitefly was tested for acute oral intragastric pathogenicity and toxicity in CD-1 mice. Animals were inoculated by gavage with only one dose (10⁸ conidia/animal) of viable (72 mice), heat-killed (24 mice) fungus and compared to 18 control mice. Clinical observations were done daily; mycological and histological tests were performed during necropsies at days 3, 10, 17, and 21 after the inoculation. No mice were clinically ill or died. At the end of the study, their mean weight corresponded to healthy adults. Positive fungal cultures of feces were obtained only 24 h after inoculation. Positive cultures were found in 15 out of 360 organs (liver, spleen, kidney, brain, lung) in 12 of 72 mice inoculated with viable conidia. Gross pathology exhibited splenomegaly and liver paleness in mice inoculated with viable and heat-killed fungus. Non-germinated conidia were observed in studied organs, without any pathological tissue reaction, suggesting no mycological or histopathological evidence of fungal multiplication. The fungus was able to persist, but did not cause permanent damage to the host. This study supports the non-pathogenic/toxic status of P. fumosoroseus EH-506/3 when administered intragastrically in mice.