• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.151-155
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• 1985

Female BALB/c mice weighing 18~20g were immunized by three injections of $1{\times}10^6$ Naegleria iowleri trophozoites intraperitoneally at the interval of one week 6 times for the pregnant mice and 3 times for the offspring mice. One week after immunization the mice were challenged intranasally with N. fcwleri trophozoites $5{\times}10^4$ under secobarbital anesthesia. Experimental primary amoebic meningoencephalitis developed between day 7 and 16 after infection. All mice were dead due to amoebic meningoencephalitis in all experimental groups except in the offspring born to non-immune mothers. Mean of survival time, which is the duration of survival of mice from infection to death, was delayed in the groups of mice born to immune mothers, immune mice born to immune mothers. Active or passive protective immunity against N. fowleri infection was demonstrated in the ismunized mice and mice born to immune mothers. But the effectiveness of immunization was greatly impaired in terms of mortality in the immune mice born to immune mothers when N. fowulsri was infected intranasally.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.156-164
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• 1985

To elucidate the effect of splenectomy on the development of experimental primary amoebic meningoencephalitis in mice, the death rate and survival time of mice infected intranasally with Naegleria fowleri trophozoites $5{\times}10^4$ cultivated in CGVS medium were compared according to the mouse age when splenectomy was done, and post-operation until experimental infection. Immunodigusion was undergone to detect the presence of serum antibod). due to N, fowleri infecttion in mice. Polyacrylamide gel electrophoresis was done to compare the protein fractions of mouse serum in each experimental groups. In experiment I, splenectomy was done 3 weeks and infection 4 weeks after birth, the death rate of control, sham operated and splenectomized group were 100%, 85% and 95%, and the mean survival time after infection 7.3 days, 7.5 days and 7.8 days, respectively. In experiment II, splenectomy was undergone 3 weeks and infection 6 weeks after birth, the death rate of of control, sham operated and splenectomized group were 95%, 95% and 95%, and the mean survival time after infection 12.1 days, 11.5 days and 11.5 days, respectively. In experiment III, splenectomy was done 5 weeks and infection 6 weeks after birth, the death rate of control, sham operated and splenectomized group were 95%, 90% and 95%, and the mean survival time after infection 8.1 days, 8.3 days and 8.5 days, respectively. By Ouchterlony immunodigusion, anti-JV. fowleri antibody in the serum of mouse with primary amoebic meningoencephalitis was detected against a N. fowleri antigen, which was prepared by ultrasonication of N, fowleri trophozoites, each reacting two lines of precipitation. The patterns of serum fractions by polyacrylamide gel electrophoresis were different between control and sham operated groups from splenectomized group in fraction II, III and V, the sera of which were collected after N. fowleri infection. This results may be summarized as that splenectomy has no effect on the development of primary amoebic meningoencephalitis in mice.

• 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.55 no.3
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• pp.233-238
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• 2017

Pathogenic Naegleria fowleri, Acanthamoeba castellanii, and Acanthamoeba polyphaga, are distributed worldwide. They are causative agents of primary amoebic meningoencephalitis or acanthamoebic keratitis in humans, respectively. Trophozoites encyst in unfavorable environments, such as exhausted food supply and desiccation. Until recently, the method of N. fowleri encystation used solid non-nutrient agar medium supplemented with heat-inactivated Escherichia coli; however, for the amoebic encystment of Acanthamoeba spp., a defined, slightly modified liquid media is used. In this study, in order to generate pure N. fowleri cysts, a liquid encystment medium (buffer 1) modified from Page's amoeba saline was applied for encystation of N. fowleri. N. fowleri cysts were well induced after 24 hr with the above defined liquid encystment medium (buffer 1). This was confirmed by observation of a high expression of differential mRNA of nfa1 and actin genes in trophozoites. Thus, this liquid medium can replace the earlier non-nutrient agar medium for obtaining pure N. fowleri cysts. In addition, for cyst formation of Acanthamoeba spp., buffer 2 (adjusted to pH 9.0) was the more efficient medium. To summarize, these liquid encystment media may be useful for further studies which require axenic and pure amoebic cysts.

• 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.23 no.1
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• pp.165-172
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• 1985

Present study aimed to elucidate the immunosuppressive effect of prednisolone on Naegleria fowlsri infection in mice. N. fowleri was cultured in CGVS medium (Willert and Le Ray, 1973) . White female mice, weighing about 18g, used for experiments were divided into five groups; untreated control group, prednisolone treated groups (before, during and after infection), and only prednisolone treated group. In the prednisolone treated group, the hormone was injected intramuscularly 5 doses of 10 mg/kg every other day. According to designated time of treatment, each mouse was challenged with $1{\times}10^5$ N. fowleri intranasally. Changes of body weights, clinical manifestations and number of dead mouse were observed. Brain and lung tissues of dead mice were cultured in the non-nutrient agar (Kasprzak and Mazur, 1972), or stained with hematoxylin.rosin for the examination of histopathological changes. Results of the experiment are summarized as follows: Mortality among the prednisolone treated groups was higher than that in untreated control group, and among the treated groups, the pretreated group showed shorter survival time. Body weights among untreated control mice showed no significant increase, however, treated groups of mice showed the decrease during the administration and recovery of the weights were observed at 2 to 3 days after the completion of treatment. In the treated control groups, the infected mice began to show the pathologic findings 5 days after infection while, the untreated mice began to show the findings 8 days after infection. Tissue damages in brain and lung occurred due to virulence of amoeba were more severe among treated mice than that in untreated control group. The above mentioned results suggest that the treatment with prednisolone weaken the resistance of mice against N. fowleri infection, and probably induce more severe primary amoebic meningoencephalitis. Especially severe pathological findings were shown in pre-treated group, compared with untreated group.

• 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.27 no.2
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• pp.73-78
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• 1989

Cell-mediated and humoral immune reactions in mice infected with pathogenic Acanthamoeba culbertsoni were observed according to the period of time after amoebic infection by intranasal inoculation. The degrees of blastogenesis of spleen cells induced by mitogens, which were measured using radioactive [$^3H$]-thynndine, were compared between infected and non-infected control groups. The mitogens used in this blastogenesis experiment were concanavalin A (Con A) and lipopolysaccharide(LPS). On the other hand, enzyme-linked immunosorbent assay(ELISA) was employed for the detection of humoral antibodies against A, culbertsoni. The levels of blastogenesis of splenocytes and strum litres in the experimental group showed increasing tendency a week after inoculation of A. cuzberiseni, although there was no difference between the experimental and control groups in other periods of the experimental time.

• 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.

• Journal of Ecology and Environment
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• v.47 no.3
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• pp.118-133
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• 2023

Background: Free-living amoebae (FLA) are widely distributed in freshwater, seawater, soil, and extreme environments, and play a critical role as feeders on diverse preys in the ecosystem. Also, some FLA can become opportunistic pathogens in animals including humans. The taxa Amoebozoa and Heterolobosea are important amoeboid groups associated with human pathogens. However, the identification and habitat of amoebae belonging to Amoebozoa and Heterolobosea remain poorly reported in the Republic of Korea. This study highlights the first record for identification and source of four amoebae including putative pathogens in the Republic of Korea. Results: In the present study, four previously reported FLA were isolated from freshwaters in Sangju Gonggeomji Reservoir (strain GO001), one of the largest reservoirs during the Joseon Dynasty period, and along the Nakdong River, the largest river in the Republic of Korea (strains NR5-2, NR12-1, and NR14-1) for the first time. Microscopic observations and 18S rDNA phylogenetic trees revealed the four isolated strains to be Acanthamoeba polyphaga (strains NR5-2 and NR12-1), Tetramitus waccamawensis (strain GO001), and Naegleria australiensis (strain NR14-1). Strains NR5-2 and NR12-1 might be the same species and belonged to the morphological Group 2 and the T4 genotype of Acanthamoeba. Strain GO001 formed a clade with T. waccamawensis in 18S rDNA phylogeny, and showed morphological characteristics similar to previously recorded strains, although the species' flagellate form was not observed. Strain NR14-1 had the typical morphology of Naegleria and formed a strongly supported clade with previously recorded strains of N. australiensis in phylogenetic analysis of 18S rDNA sequences. Conclusions: On the bases of morphological and molecular analyses, four strains of FLA were newly observed and classified in the Republic of Korea. Three strains belonging to the two species (A. polyphaga and N. australiensis) isolated from the Nakdong River have the potential to act as opportunistic pathogens that can cause fatal diseases (i.e. granulomatous amoebic encephalitis, Acanthamoeba Keratitis, and meningoencephalitis) in animals including humans. The Nakdong River in the Republic of Korea may provide a habitat for potentially pathogenic amoebae, but additional research is required to confirm the true pathogenicity of these FLA now known in the Republic of Korea.