• Parasites, Hosts and Diseases
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• v.57 no.3
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• pp.217-223
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• 2019

Acanthamoeba castellanii has ubiquitous distribution and causes primary acanthamoebic keratitis (AK). AK is a common disease in contact lens wearers and results in permanent visual impairment or blindness. In this study, we observed the cytopathic effect, in vitro cytotoxicity, and secretion pattern of cytokines in human corneal epithelial cells (HCECs) induced by A. castellanii trophozoites and/or cysts. Morphological observation revealed that panked dendritic HCECs co-cultured with amoeba cysts had changed into round shape and gradually died. Such changes were more severe in co-culture with cyst than those of co-cultivation with trophozoites. In vitro cytotoxicity assay revealed the highest cytotoxicity to HCECs in the co-culture system with amoeba cysts. A. castellanii induced the expression of $IL-1{\alpha}$, IL-6, IL-8, and CXCL1 in HCECs. Secreted levels of $IL-1{\alpha}$, IL-6, and IL-8 in HCECs co-cultured with both trophozoites and cysts were increased at an early incubation time (3 and 6 hr). These results suggested that cytopathic changes and pro-inflammatory cytokines release of HCECs in response to A. castellanii, especially amoebic cysts, are an important mechanism for AK development.

• Parasites, Hosts and Diseases
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• v.38 no.2
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• pp.99-102
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• 2000

In order to observe the cytotoxicity of Acanthamoeba spp., which were isolated from contact lens containers as ethiological agents for the probable amoebic keratitis in Korea, the crystal violet staining method and LDH release assay were carried out. In the crystal violet staining method, among eight contact lens container isolates, isolate 3 (Acanthauloeba KA/LS5) showed 83.6% and 81.8% of cytotoxicity, and isolate 7 (Acanthamoeba KA/LS37) showed 28.2% and 25.1% of cytotoxicity, in 1 mg/ml and 0.5 mg/ml Iysate treatments, respectively. Acanthamoeba cutbertsoni and A. healyi showed 84.0% and 82.8% of cytotoxicity. Similar results were observed in A. costellunii and A. hafchefti which showed 83.6% and 75.5% or cytotoxicity. Acanthamoeba roureba and A. polyphaga showed 9.0% and 1.7% of cytotoxicity. In the LDH release assay, isolate 3 (20.4%) showed higher cytotoxicity than other isolates in 1 mg/ml Iysate treatment. The results provide that at least isolate 3 has the cytotoxic effect against CHO cells and seems to be the pathogenic strain.

• 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.37 no.4
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• pp.229-236
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• 1999

In order to refer to the basic information regarding the identification of isolates obtained from a contact lens container in Korea, the isoelectric focusing gel electrophoresis was employed to compare the isoenzyme band patterns among Acanthamoeba spp. including eight isolates and the simple pairwise dissimilarity analysis was carried out. For an alkaline phosphate development, isolate 7 and Acanthamoeba polyphaga showed homologous band patterns, and isolates 1, 2, and 3 showed the same patterns. For lactate dehydrogenase, similar patterns were observed in isolates 2 and 3. Isolates 3 and 5 showed homologous band patterns for malate dehydrogenase and glucose phosphate isomerase. For hexokinase, isolates 4, 7, and A. hatchetti showed the same band patterns. In others, a considerable number of interstrain polymorphisms was observed in nine isoenzyme band patterns. In Acanthamoeba group II, genetic distances among isolates 1, 2, 3, 4, and 5 ranged from 0.104 to 0.200. In comparison to A. castellanii, A. hatchetti, and A. poIyphaga, genetic distances of isolates 7 and 8 were 0.254 and 0.219, respectively. In Acanthamoeba group III, including A. culbertsoni, A. healyi, and A. royreba, isolate 6 had genetic distances which ranged from 0.314 to 0.336. Finally, when comparing to the six reference Acanthamoeba, it was possible to classify isolates 1, 2, 3, 4, and 5, as genetically close-related species and as independent species group. Furthermore, isolates 6, 7 and 8 were identified as independent species as well.