Cytopathogenicity ofNaegleria fowleri in mammalian cell cultures

John, David T.; John, Rebecca A.

doi:10.1007/bf00931066

Cited by 17 publications

(10 citation statements)

References 27 publications

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“…and Naegleria spp. (De Jonckheere 1980; John & John 1989). The pattern of CPE is different between amoeba species, but typically cytolysis is the end point and can occur in as little as 2 days following incubation (De Jonckheere 1980).…”

Section: Discussionmentioning

confidence: 99%

“…In addition to limited reproducibility and the influence of temperature, the in vitro cytopathogenicity of amoebae is also dependent upon the target cell used. For example, Naegleria fowleri is cytopathogenic for mammalian lung, kidney, foreskin, ovary, connective tissue, neuroblastoma and carcinoma cell lines, but the African green‐monkey kidney (Vero) cell line has proven to be the most effective in assessing the pathogenicity of strains of this species (John & John 1989). In the present study CPE of gill derived Neoparamoeba sp.…”

Section: Discussionmentioning

confidence: 99%

“…These cytopathic effects (CPE) are for the most part the result of proteolytic enzymes causing direct cytolysis or stimulating apoptosis of cells in the infected tissue. The nature of the CPE of these organisms can be modelled in vitro using cell cultures as the target tissue (John & John 1989). The cytopathogenicity of gill derived Neoparamoeba sp.…”

Section: Introductionmentioning

confidence: 99%

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In vitro interactions between Neoparamoeba sp. and Atlantic salmon epithelial cells

Bütler

Nowak

2004

Journal of Fish Diseases

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Neoparamoeba sp., including the putative aetiological agent of amoebic gill disease in cultured fish (N. pemaquidensis), were incubated in vitro with an Atlantic salmon gill epithelium (RGE-2) cell line. Proliferation by the amoeba population was dependent upon culture osmolarity; no growth occurred at 330 mm x kg(-1) but a sixfold increase was observed at 1000 mm x kg(-1). At 780 mm x kg(-1) there was a fourfold increase in the amoeba population but a concurrent decrease in RGE-2 cell density that was significantly greater than that caused by the high culture osmolarity alone. This apparent cytopathic effect (CPE) developed rapidly and resulted in complete cytolysis of the monolayer in 5 days. CPE occurred in multiple foci and presented as cell vacuolation, rounding and clumping, and the rapid clearance of large areas of the cell monolayer. The possibility that CPE is because of the presence of Neoparamoeba sp. derived cytolytic products is discussed in the context of the pathology of the disease in vivo and the occurrence of secreted cytopathogenic compounds in other amoeba species.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In vitro interactions between Neoparamoeba sp. and Atlantic salmon epithelial cells

Bütler

Nowak

2004

Journal of Fish Diseases

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“…Naegleria trophozoites can produce CPE by troglocytosis, contact-dependent lysis, or a combination of the two (8,10,15,16). Although trophozoites of Acanthamoeba spp.…”

Section: Discussionmentioning

confidence: 99%

Apoptosis as a mechanism of cytolysis of tumor cells by a pathogenic free-living amoeba

1994

Parasitology Today

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Previous studies have shown that trophozoites of the pathogenic free-living amoeba Acanthamoeba castellanii rapidly lysed a variety of tumor cells in vitro. Tumor cells undergoing parasite-mediated lysis displayed characteristic cell membrane blebbing reminiscent of apoptosis. The present investigation examined the role of apoptosis (programmed cell death) in Acanthamoeba-mediated tumor cell lysis. The results showed that more than 70%o of tumor cell DNA was fragmented following exposure to Acanthamoeba cell extracts. By contrast, only 7% of untreated control cells underwent DNA fragmentation. DNA fragmentation increased significantly in a dose-dependent fashion following concentration of the parasite extract. Apoptosis was also confirmed by DNA ladder formation. Characteristic DNA ladders, consisting of multimers of approximately 180 to 200 bp, were produced by tumor cells exposed to Acanthamoeba cell extracts. The morphology of tumor cell lysis was examined by light and scanning electron microscopy. Tumor cells exposed to parasite extract displayed morphological features characteristic of apoptosis including cell shrinkage, cell membrane blebbing, formation of apoptotic bodies, and nuclear condensation. By contrast, similar effects were not found in tumor cells exposed to extract similarly prepared from normal mammalian cells (i.e., human keratocytes). The results suggest that at least one species of pathogenic free-living amoeba is able to lyse tumor cells by a process that culminates in apoptosis.Acanthamoeba species are ubiquitous pathogenic free-living protozoal organisms that have been isolated from an unbelievably diverse range of habitats (17).

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“…1986). It is commonly accepted that the pathogenicity of N. fowleri can be increased by serial mouse brain passages (John & Howard, 1993;Marciano-Cabral, 1988) as well as by passages in tissue cultures (John & John, 1989). In vitro, it has been shown that trophozoites destroy their target cells by a combination of phagocytosis and the cytolytic action of secreted enzymes (Visvesvara & Callaway, 1974).…”

Section: Introductionmentioning

confidence: 99%

Development of a high- versus low-pathogenicity model of the free-living amoeba Naegleria fowleri

et al. 2012

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Species in the genus Naegleria are free-living amoebae of the soil and warm fresh water. Although around 30 species have been recognized, Naegleria fowleri is the only one that causes primary amoebic meningoencephalitis (PAM) in humans. PAM is an acute and fast progressing disease affecting the central nervous system. Most of the patients die within 1-2 weeks of exposure to the infectious water source. The fact that N. fowleri causes such fast progressing and highly lethal infections has opened many questions regarding the relevant pathogenicity factors of the amoeba. In order to investigate the pathogenesis of N. fowleri under defined experimental conditions, we developed a novel high-versus low-pathogenicity model for this pathogen. We showed that the composition of the axenic growth media influenced growth behaviour and morphology, as well as in vitro cytotoxicity and in vivo pathogenicity of N. fowleri. Trophozoites maintained in Nelson's medium were highly pathogenic for mice, demonstrated rapid in vitro proliferation, characteristic expression of surface membrane vesicles and a small cell diameter, and killed target mouse fibroblasts by both contact-dependent and -independent destruction. In contrast, N. fowleri cultured in PYNFH medium exhibited a low pathogenicity, slower growth, increased cell size and contact-dependent target cell destruction. However, cultivation of the amoeba in PYNFH medium supplemented with liver hydrolysate (LH) resulted in trophozoites that were highly pathogenic in mice, and demonstrated an intermediate proliferation rate in vitro, diminished cell diameter and contact-dependent target cell destruction. Thus, in this model, the presence of LH resulted in increased proliferation of trophozoites in vitro and enhanced pathogenicity of N. fowleri in mice. However, neither in vitro cytotoxicity mechanisms nor the presence of membrane vesicles on the surface correlated with the pathologic potential of the amoeba. This indicated that the pathogenicity of N. fowleri remains a complex interaction between as-yet-unidentified cellular mechanisms.

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Cytopathogenicity ofNaegleria fowleri in mammalian cell cultures

Cited by 17 publications

References 27 publications

In vitro interactions between Neoparamoeba sp. and Atlantic salmon epithelial cells

In vitro interactions between Neoparamoeba sp. and Atlantic salmon epithelial cells

Apoptosis as a mechanism of cytolysis of tumor cells by a pathogenic free-living amoeba

Development of a high- versus low-pathogenicity model of the free-living amoeba Naegleria fowleri

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