• Parasites, Hosts and Diseases
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• v.23 no.2
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• pp.293-299
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• 1985

This study is to verify the protective ability against experimental Naegleria meningoencephalitis by immunization with Naegleria fowleri in mice. Naegleria fewleri, strain 0359, and Naegleria gruberi, strain EGB, were used in this study, and cultured in CGVS medium akenically. Inbred BALB/C mice, weighing about 20g, were immunized by three intraperitoneal injection of $1{\times}10^6$ N. fowleri trophozoites at the interval of one week. This N. fowleri trophozoites antigen was fixed with 5% formaldehyde. N. fowleri trophozoites from culture were homogenized with soiicator at $4^{\circ}C$ as monitored by phase contrast microscopy, and their membrane and cell content preparations were made for the immunization of mice. Their inoculation dose in volume was equivalent to the $1{\times}10^6$ trophozoites in each injection for immunization. And N. gruberi trophosoites, whieh was fixed with 5% formaldehyde, were also used for immunisation. Mice were inoculated intranasally with $5{\times}10^4$ N. fowleri trophozoites in a 511 suspension under anesthesia by as intraperitoneal injection of about 1 mg secobarbiturate. Nervousness, rotation or sluggish behaviour were observed in the mice which were infected with N. fewleri. Necrotic lesion was demonstrated in the anterior portion of brain, especially in the olfactory lobe. The inflammatory cell infiltration with numerous H. fowleri trophozoites was noticed. This pathological changes were more extensive in the control than in the experimental groups. Mice were dead due to experimental primary amoebic meningoencephalitis that developed between 8 days and 23 days after inoculation. Mortality rate of the mice was low in the immunized experimental group. Mean survival time, which is the survival duration of mice from the infection to death, was prolonged significantly in the immunized mice except in the mice immunized with JV, fowleri membrane. Even in the mice immunized with N. gruberi, survival time was delayed. In summary, the effectiveness of immunization is demonstrated in terms of protective immunity against Naegleria meningoencephalitis in mice.

• Parasites, Hosts and Diseases
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• v.59 no.5
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• pp.501-505
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• 2021

The pathogenic free-living amoeba Naegleria fowleri causes primary amoebic meningoencephalitis, a fatal infection, by penetrating the nasal mucosa and migrating to the brain via the olfactory nerves. N. fowleri can induce host cell death via lytic necrosis. Similar to phosphorylation, O-linked β-N-acetylglucosamine (O-GlcNAc) glycosylation (O-GlcNAcylation) is involved in various cell-signaling processes, including apoptosis and proliferation, with O-GlcNAc addition and removal regulated by O-GlcNAc transferase and O-GlcNAcase (OGA), respectively. However, the detailed mechanism of host cell death induced by N. fowleri is unknown. In this study, we investigated whether N. fowleri can induce the modulation of O-GlcNAcylated proteins during cell death in Jurkat T cells. Co-incubation with live N. fowleri trophozoites increased DNA fragmentation. In addition, incubation with N. fowleri induced a dramatic reduction in O-GlcNAcylated protein levels in 30 min. Moreover, pretreatment of Jurkat T cells with the OGA inhibitor PUGNAc prevented N. fowleri-induced O-deGlcNAcylation and DNA fragmentation. These results suggest that O-deGlcNAcylation is an important signaling process that occurs during Jurkat T cell death induced by N. fowleri.

• Korean Journal of Veterinary Service
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• v.42 no.4
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• pp.169-175
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• 2019

Naegleria fowleri, a pathogenic free-living amoeba, leads to a fatal infection known as primary amebic meningoencephalitis (PAM) in human and animals. PAM is an acute, fulminant, necrotizing, and hemorrhagic disease that leads to death in approximately seven days. In this study, we investigate the cytotoxicity of target cells and the secreted molecules of N. fowleri under the non-contact condition. The target cell (U87MG cell) treated with N. fowleri lysates showed no morphological changes and no cytotoxicity. By contrast, the U87MG cells co-cultured with N. fowleri trophozoites under the non-contact condition induced morphological changes and reduction in number. When U87MG cells were co-cultured with N. fowleri trophozoites under the non-contact condition for 30 min, 2 hr, and 4 hr, the levels of cytotoxicity of target cells were 32.3, 35.5, and 37.8%, respectively. Particularly, when the ratio of amoeba to target cells is 10 to 1, the level of cytotoxicity of target cells was 49.7% at 30 min. To show the proteins secreted from N. fowleri under the non-contact condition, we carried out 2D electrophoresis and observed 6 major proteins. Finally, these results suggest that the molecules released from N. fowleri under the non-contact condition induce the cell death and this process is an important step in pathogenesis of N. fowleri.

• Parasites, Hosts and Diseases
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• v.21 no.2
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• pp.234-240
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• 1983

The pathogenicity of free-living amoeba, Waegleria fcwleri, is influenced according to the strain, cultural condition and host (Culbertson et at., 1968; Carter, 1970; Wong et at., 1975), Phillips (1973) demonstrated that Entamoeba histolytica became avirulent after more than 2 year maintenance in axonic culture in vitro. This study was carried out to compare the difference in pathogenicity between two strains of N. fowleri, one of a prolonged maintenance in arsenic medium and the other one obtained by serial brain passage in mice. The 0 strain was that N. fowleri had cultivated axenically more than 7 years in CGVS medium. The 2-1 strain was obtained from the brain of mouse inoculated intranasally with a strain, which was from the mouse brain infected with 0 strain, and cultured for 15 weeks until the beginning of this experiment. White male mice weighing 18-22 g were used. Mice were anesthetized by an intraperitoneal injection of about 1 mg secobarbital, and inoculated intranasally with $10{\times}$10^4 live N. fowleri trophoBoites in a $5{\;}{\mu}l$ cell suspension. Sluggish behaviour, nervousness, rotation and leg paralysis were developed earlier and more frequently in the 2-1 experimental group than the control 0 group. Pathological changes such as inflammatory and necrotic lesion were observed in the olfactory and anterior portion of brain, and these changes were more extensive in the 2-1 group. The edematous and inflammatory changes in lung were demonstrated in mice died after 13th day post-inoculation. The experimental mice of 2-1 group began to die suddenly from 7th day post-inoculation, and the survival time in 2-1 group mice was shorter than 0 group mice. The typical primary amoebic meningoencephalitis was developed in the mice inoculated intranasally with N. fowleri. The prolonged maintenance of N. fowleri amoebae in axonic CGVS medium was observed to have lost their original pathogenicity for mice, but their pathogenicity was restored by serial brain passage in mice.

• Biomedical Science Letters
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• v.16 no.4
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• pp.221-227
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• 2010

To elucidate the invasion mechanism of pathogenic Naegleria fowleri, especially a receptor-ligand recognition, we investigated the in vitro cytotoxicity of pathogenic N. fowleri and nonpathogenic N. gruberi to murine macrophages, RAW 264.7, by adding four kinds of saccharides, ${\alpha}$-fucose, ${\beta}$-galactose, ${\alpha}$-D-mannopyranoside (${\alpha}$-mannose) and xylose. There was not enough of a difference in the cytotoxicity of N. fowleri treated with 10 mM of each saccharide. In particular, the cytotoxicity of N. fowleri was highly inhibited by 100 mM ${\alpha}$-mannose, which was 62.3% inhibition calculated by the analysis of lactate dehydrogenase (LDH) release assay. Although murine macrophages were not significantly destroyed by nonpathogenic N. gruberi under hematoxylin staining, the cytotoxicity of N. gruberi was inhibited from 31.5% to 14.5% (P<0.01) by 100 mM ${\alpha}$-mannose treatment. The binding of N. fowleri to macrophages was inhibited from 33% to 50% by 100 mM ${\alpha}$-mannose. Furthermore, as results of the adhesion assays which were performed to determine whether binding of Naegleria is mediated by saccharides-binding protein, the binding ability of N. fowleri as well as N. gruberi was inhibited by 100 mM ${\alpha}$-mannose.

• Parasites, Hosts and Diseases
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• v.22 no.2
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• pp.253-258
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• 1984

Experimentally, primary amoebic meningoencephalitis (PAM) is induced by Naegleria fowleri in mouse and development of PAM may be inauenced by the strain, weight and sex of mouse, and inoculum size of N. fowleri trophozoite. In this paper, the effect of these factors on PAM development of mouse was studied. N. fowleri trophozoites, strain 0359, were introduced into mouse intranasally under secobarbital anesthesia (0.05mg/g). 1. PAM was developed more frequently in BALB/C mouse than ICR mouse. 2. The survival time of mouse with PAM was influenced by the weight, that is, it was shorter in 15 g mouse than in the heavier groups. 3. No difEerence was observed on PAM development according to sect. 4. In case of inoculated amoeba, PAM incidence of $0.5{\times}10^4$ was markedly decreased.

• Parasites, Hosts and Diseases
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• v.27 no.2
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• pp.79-86
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• 1989

A pathogenic free-living amoeba, Naegleria fowleri, causes primary amoebic meningoencephalitis to human and experimental animals. This infection is rare, but the mortality is very high. Nowadays, drug treatment or active immunization of human or mice are being tried with partial effectiveness. This study shows passive immunization effect by transfer of immunized spleen cells, serum, or milk from immunized mother in mouse experimental model. Young BALB/c mice were immunized intraperitoneally with $2~3{\times}10^{6}$ trophozoites of N. fowleri, and spleen cells and sera were collected for injection to recipient mice. There were seven transfer groups, i.e., immunized mouse serum, spleen cells, serum and spleen cells, normal mouse serum, spleen cells, serum and spleen cells, and control group. Three days later, BALB/c mice were inoculated with $1{\times}10^{4}$ trophozoites of N. fowleri intranasally. After infection, decreased mortality ana prolonged survival time of mice were noted in immunized Bloops compared with non.immuniBed control group. The groups Injected with immunized spleen cells or normal serum shewed lower moltality than that of controls bult showed no changes of Serum IgG level. The groups injected with immunized serum or normal spleen cells showed increased serum IgG level after immunization but hundred percent mortality was observed. Mother mice were ifnfnunised increperitqneeliy with $2~3{\times}10^{6}$ trephozoites of N. fowleri at the end of pregnancy and weaning Period. Soon after the delivery, Jitters born of non-immunszed mother were matched with immunized mother for feeding immune milk. After three weeks, the litters were infected with $1{\times}10^{4}$ trophozeites of N. fowleri or sacrificed for serum collection to measure the IgG levels. The results show that anti-JV. fowleri IgG from mother was transferred to litter through milk but this IgG did not inauence the mortality or survival time of the infected mice.

• Parasites, Hosts and Diseases
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• v.30 no.1
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• pp.33-42
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• 1992

Naegleria fowleri, a free-living amoeba commonly found in moist soil and fresh water, enters the body via the nasal mucosa and migrates along the olfactory nerve to t he brain, where it causes acute amoebic meningoencephalitis. In the present study 7 clones secreting monoclonal antibodies (McAbs) against N. fowleri were produced and the effector function of them was investigated. Their isotopes were IgGl (Nf 1, Nf 154), 19G3 (Nf 137) and 19A (Nf 1, Nf 2, Nf 256, Nf 279). Five McAbs (McAb Nf 2, Nf 279, Nf 27, Nf 154, Nf 137) were specific for N. fowleri by ELISA and recognized the antigenic determinants located on the trophoBoite surface by IFAT and immunoperoxidase stain. These aye McAbs had capacity to agglutinate N. fowleri trophozoites and inhibited the growth of the amoeba in culture medium. McAb Nf 2 inhibited proliferation of trophozoites in vitro significantly. Also the cytotoxicity of JV. fowleri against CHO cell was reduced in the presence of McAb Nf 2 and McAb Nf 154. From these results McAb Nf 2 was confirmed to weaken the virulence of the amoeba among 7 screened McAbs.

• Parasites, Hosts and Diseases
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• v.25 no.2
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• pp.195-198
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• 1987

In order to test the function of Iymphocytes in Naegleria fowleri-nniected mice, the in nitro blastogenic response of splenocyte cultures to non-specific mitogens was studied. Concanavalin A and lipopolysaccharide stimulation were used as tests of T cell and B cell function. For the first 14 days following N. fowleri infection, Iymphoblastic transformation induced by T-cell mitogen was markedly reduced in comparison to the uninfected control mice. The blastogenic response to B-cell mitogen remained depressed in the infected mice up to 14 days after infection. The fluorescent antibody titers of sera of N. fowleri infected mice were between 1 : 4 and 1 : 32. The results suggest that there is a suppression of cell mediated immunity during the acute course of experimental Naegleria meningoencephalitis in mice.

• Biomedical Science Letters
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• v.27 no.4
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• pp.323-328
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• 2021

Naegleria fowleri is a free-living amoeba causing primary amoebic encephalitis. In this study, we analyzed how the N-aceytlglucosamine (GlcNAc) and D-galactose affected the interaction between Naegleria fowleri and methicillin-resistant Staphylococcus aureus (MRSA) or Escherichia coli O157:H7, and the interaction with bacteria when monosaccharides were treated with N. fowleri for a longer pre-incubation time. When GlcNAc was treated with N. fowleri for 1 hr, the E. coli association was almost the same as that of the control not treated with GlcNAc until the concentration of GlcNAc was 25 mM. However, the E. coli association was reduced by approximately 91% with 100 mM GlcNAc. E. coli invasion into N. fowleri showed statistical significance only in the group treated with 100 mM GlcNAc. The interaction when treated with galactose showed a very different pattern in the 50 mM galactose group than when treated with GlcNAc. In the MRSA interaction, a statistically significant decrease in association (76.3% by GlcNAc and 88.7% by galactose) and invasion (3.6% by GlcNAc and 9.3% by galactose) was shown by the concentration of two 100 mM monosaccharides. The group treated with monosaccharides at the same time showed almost no difference in all interactions from the group treated with monosaccharides at the same time. Taken together, it suggested that the effect of monosaccharides on the interaction of several Gram-negative or positive bacteria and the evidence that the interaction could be enhanced by longer pre-incubation time.