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International Journal of Medical... Aug 2005The virulence-associated SpvB protein of Salmonella enterica is a mono (ADP-ribosyl)transferase defined to target mammalian actin. Exposure of Acanthamoeba rhysodes cell...
The virulence-associated SpvB protein of Salmonella enterica is a mono (ADP-ribosyl)transferase defined to target mammalian actin. Exposure of Acanthamoeba rhysodes cell lysate with SpvB and [32P]nicotinamide adenine dinucleotide (NAD) was here observed to result in labeling of a protein of 43 kDa that subsequently was identified as actin by immunoprecipitation. In parallel, ADP-ribosylation promoted degradation of the protozoan actin. SpvB-mediated actin degradation occurred in the presence of the serine protease inhibitor phenylmethylsulfonylfluoride (PMSF), but was inhibited upon addition of novobiocin, an inhibitor of mono (ADP-ribosyl)transferase activity, or upon addition of EDTA. Infection of A. rhysodes with SpvB-proficient S. enterica serovariant Dublin resulted in cytotoxicity and in characteristic SpvB-mediated actin degradation. Cells infected with SpvB-deficient bacteria showed a decrease in cytotoxicity and lack of actin degradation. Combining these results show that SpvB formally can ADP-ribosylate A. rhysodes actin but that the protozoan cell has the capacity to subsequently degrade ADP-ribosyl-tagged actin. These observations illustrate a hitherto undefined consequence of actin modification, and define a new pathway in the cellular actin dynamics.
Topics: ADP Ribose Transferases; Actins; Adenosine Diphosphate Ribose; Amoeba; Animals; Salmonella enterica; Virulence Factors
PubMed: 16128395
DOI: 10.1016/j.ijmm.2005.04.008 -
The Korean Journal of Parasitology Mar 2005The taxonomy of Acanthamoeba spp., an amphizoic amoeba which causes granulomatous amoebic encephalitis and chronic amoebic keratitis, has been revised many times. The...
Evaluation of taxonomic validity of four species of Acanthamoeba: A. divionensis, A. paradivionensis, A. mauritaniensis, and A. rhysodes, inferred from molecular analyses.
The taxonomy of Acanthamoeba spp., an amphizoic amoeba which causes granulomatous amoebic encephalitis and chronic amoebic keratitis, has been revised many times. The taxonomic validity of some species has yet to be assessed. In this paper, we analyzed the morphological characteristics, nuclear 18s rDNA and mitochondrial 16s rDNA sequences and the Mt DNA RFLP of the type strains of four Acanthamoeba species, which had been previously designated as A. divionensis, A. parasidionensis, A. mauritaniensis, and A. rhysodes. The four isolates revealed characteristic group II morphology. They exhibited 18S rDNA sequence differences of 0.2-1.1% with each other, but more than 2% difference from the other compared reference strains. Four isolates formed a different clade from that of A. castellanii Castellani and the other strains in morphological group II on the phylogenetic tree. In light of these results, A. paradivionensis, A. divionensis, and A. mauritaniensis should be regarded as synonyms for A. rhysodes.
Topics: Acanthamoeba; Animals; DNA, Mitochondrial; DNA, Ribosomal; Phylogeny; Polymorphism, Restriction Fragment Length; RNA, Ribosomal, 18S
PubMed: 15793353
DOI: 10.3347/kjp.2005.43.1.7 -
Applied and Environmental Microbiology Jun 2004The ability of salmonellae to become internalized and to survive and replicate in amoebae was evaluated by using three separate serovars of Salmonella enterica and five...
The ability of salmonellae to become internalized and to survive and replicate in amoebae was evaluated by using three separate serovars of Salmonella enterica and five different isolates of axenic Acanthamoeba spp. In gentamicin protection assays, Salmonella enterica serovar Dublin was internalized more efficiently than Salmonella enterica serovar Enteritidis or Salmonella enterica serovar Typhimurium in all of the amoeba isolates tested. The bacteria appeared to be most efficiently internalized by Acanthamoeba rhysodes. Variations in bacterial growth conditions affected internalization efficiency, but this effect was not altered by inactivation of hilA, a key regulator in the expression of the invasion-associated Salmonella pathogenicity island 1. Microscopy of infected A. rhysodes revealed that S. enterica resided within vacuoles. Prolonged incubation resulted in a loss of intracellular bacteria associated with morphological changes and loss of amoebae. In part, these alterations were associated with hilA and the Salmonella virulence plasmid. The data show that Acanthamoeba spp. can differentiate between different serovars of salmonellae and that internalization is associated with cytotoxic effects mediated by defined Salmonella virulence loci.
Topics: Acanthamoeba; Animals; Bacterial Proteins; Cell Line; Colony Count, Microbial; Culture Media; Dogs; Humans; Microscopy, Electron; Salmonella enterica; Trans-Activators; Virulence
PubMed: 15184177
DOI: 10.1128/AEM.70.6.3706-3714.2004 -
International Journal For Parasitology Jun 2000Three stresses, viz heat, oxidative and pH shocks, were applied to cultures of three species of Acanthamoeba, free-living Acanthamoeba rhysodes and pathogenic...
Three stresses, viz heat, oxidative and pH shocks, were applied to cultures of three species of Acanthamoeba, free-living Acanthamoeba rhysodes and pathogenic Acanthamoeba castellanii and Acanthamoeba culbertsoni. The effect of each stressor on trophozoite integrity was evaluated by the amount of heat shock protein (HSP)60 and HSP70 produced and by exclusion of 0.2% Congo Red. HSP60 and HSP70 levels were estimated using Western blotting and subsequent densitometric analyses. Unstimulated trophozoites from A. rhysodes produced the lowest background levels of HSP60 and HSP70 and were the amoebae most affected by (mammalian-type) stresses as judged by their enhanced HSP production and decreased viability upon exposure to such conditions. In contrast, unstimulated Acanthamoeba of the pathogenic variety had relatively high background levels of test HSPs and seemed undisturbed by the types of stresses they must deal with when entering their hosts. These studies suggest that high HSP levels in amphizoic acanthamoebae may indicate their involvement in (i) tolerance induction to hosts' stressors and/or (ii) in species' virulence.
Topics: Acanthamoeba; Animals; Antibodies, Monoclonal; Blotting, Western; Chaperonin 60; Congo Red; Electrophoresis, Polyacrylamide Gel; HSP70 Heat-Shock Proteins; Hot Temperature; Hydrogen Peroxide; Hydrogen-Ion Concentration; Image Processing, Computer-Assisted; Oxidative Stress
PubMed: 10899527
DOI: 10.1016/s0020-7519(00)00060-6 -
The Korean Journal of Parasitology Jun 1998Subgenus classification of Acanthamoeba remains uncertain. Twenty-three reference strains of Acanthamoeba including 18 (neo)type-strains were subjected for...
Subgenus classification of Acanthamoeba remains uncertain. Twenty-three reference strains of Acanthamoeba including 18 (neo)type-strains were subjected for classification at the subgenus level by riboprinting. PCR/RFLP analysis of 18S rRNA gene (rDNA). On the dendrogram reconstructed on the basis of riboprint analyses, two type-strains (A. astronyxis and A. tubiashi) of morphological group 1 diverged early from the other strains and were quite distinct from each other. Four type-strains of morphological group 3, A. culbertsoni, A. palestinensis, A. healyi were considered taxonomically valid, but A. pustulosa was regarded as an invalid synonym of A. palestinensis. Strains of morphological group 2 were classified into 6 subgroups. Among them, A. griffini which has an intron in its 18S rDNA was the most divergent from the remaining strains. Acanthamoeba castellanii Castellani, A. quina Vil3, A. lugdunensis L3a, A. polyphaga Jones, A. triangularis SH621, and A. castellanii Ma strains belonged to a subgroup, A. castellanii complex. However, A. quina and A. lugdunensis were regarded as synonyms of A. castellanii. The Chang strain could be regarded as A. hatchetti. Acanthamoeba mauritaniensis, A. divionensis, A. paradivionensis could be considered as synonyms of A. rhysodes. Neff strain was regarded as A. polyphaga rather than as A. castellanii. It is likely that riboprinting can be applied for rapid identification of Acanthamoeba isolated from the clinical specimens and environments.
Topics: Acanthamoeba; Animals; DNA, Protozoan; Polymerase Chain Reaction; Polymorphism, Restriction Fragment Length; RNA, Protozoan; RNA, Ribosomal, 18S
PubMed: 9637824
DOI: 10.3347/kjp.1998.36.2.69 -
The Journal of Eukaryotic Microbiology 1996Classification of Acanthamoeba at the subgenus level has been problematic, but increasing reports of Acanthamoeba as an opportunistic human pathogen have generated an...
Classification of Acanthamoeba at the subgenus level has been problematic, but increasing reports of Acanthamoeba as an opportunistic human pathogen have generated an interest in finding a more consistent basis for classification. Thus, we are developing a classification scheme based on RNA gene sequences. This first report is based on analysis of complete sequences of nuclear small ribosomal subunit RNA genes (Rns) from 18 strains. Sequence variation was localized in 12 highly variable regions. Four distinct sequence types were identified based on parsimony and distance analyses. Three were obtained from single strains: Type T1 from Acanthamoeba castellanii V006, T2 from Acanthamoeba palestinensis Reich, and T3 from Acanthamoeba griffini S-7. T4, the fourth sequence type, included 15 isolates classified as A. castellanii, Acanthamoeba polyphaga, Acanthamoeba rhysodes or Acanthamoeba sp., and included all 10 Acanthamoeba keratitis isolates. Interstrain sequence differences within T4 were 0%-4.3%, whereas differences among sequence types were 6%-12%. Branching orders obtained by parsimony and distance analyses were inconsistent with the current classification of T4 strains and provided further evidence of a need to reevaluate criteria for classification in this genus. Based on this report and others in preparation, we propose that Rns sequence types provide the consistent quantititive basis for classification that is needed.
Topics: Acanthamoeba; Animals; Base Sequence; DNA, Protozoan; DNA, Ribosomal; Genetic Heterogeneity; Humans; Molecular Sequence Data; Phylogeny; RNA, Ribosomal, 18S
PubMed: 8976608
DOI: 10.1111/j.1550-7408.1996.tb04510.x -
Journal of the Egyptian Society of... Aug 1994Samples from different water sources of Alexandria, and from nasal passages of 500 healthy children inhabiting areas nearby these sources were examined for the presence...
Samples from different water sources of Alexandria, and from nasal passages of 500 healthy children inhabiting areas nearby these sources were examined for the presence of free-living amoebae. These samples were cultured on 1.5% non nutrient agar streaked with bacteria. Amoebae were isolated and identified by means of their morphological characters and ability to produce flagellated forms. Characteristics of the cystic stages and pattern of excystation also aided in the identification of the various species. Nine species, Naegleria gruberi, N. fowleri, Acanthamoeba rhysodes, A. glebae, A. culbertsoni, A. astronyxis, A. palestinensis, V. avara and V. inornata were isolated from the water of canals and drains. N. gruberi and A. rhysodes were found in the nasal passages of six healthy children living near the contaminated canals. No amoebae were encountered in the drinking water, swimming pools, sea and lake water included in this study.
Topics: Acanthamoeba; Amoeba; Animals; Child; Egypt; Humans; Naegleria; Nasal Mucosa; Water
PubMed: 8077745
DOI: No ID Found -
Journal of Ophthalmic Nursing &... 19931. Acanthamoeba keratitis is an uncommon but increasingly prevalent infection with the potential to cause severe ocular damage. Acanthamoeba is a nonflagellated...
1. Acanthamoeba keratitis is an uncommon but increasingly prevalent infection with the potential to cause severe ocular damage. Acanthamoeba is a nonflagellated free-living amoeba that is ubiquitous in the environment. The most common type is A castellani, but A polyphagia, A rhysodes, A culbertson, and A hatchetti have been isolated from infected eyes. 2. Clinical features include foreign body sensation, blurred vision, tearing, and photophobia. There is minimal pain in the early stages of infection, but severe pain is a manifestation of the advanced stages of the disease. 3. The incidence of Acanthamoeba keratitis appears to be decreasing because of increased awareness, but education emphasizing proper lens sterilization is essential and should be carried out when contact lenses are first dispensed.
Topics: Acanthamoeba Keratitis; Humans; Primary Prevention; Prognosis
PubMed: 8158668
DOI: No ID Found -
Neurology Dec 1991A 39-year-old man with AIDS died after developing a variety of neurologic symptoms and signs. CT showed multiple enhancing lesions in the cerebral hemispheres and...
A 39-year-old man with AIDS died after developing a variety of neurologic symptoms and signs. CT showed multiple enhancing lesions in the cerebral hemispheres and cerebellum. Postmortem examination revealed parenchymal hemorrhagic and necrotizing lesions with a thrombo-occlusive vasculitis due to Acanthamoeba, which was typed as Acanthamoeba group 2, probably A rhysodes, by immunofluorescence.
Topics: Acanthamoeba; Acquired Immunodeficiency Syndrome; Adult; Amebiasis; Animals; Brain; Encephalitis; Granuloma; Humans; Male; Tomography, X-Ray Computed
PubMed: 1745363
DOI: 10.1212/wnl.41.12.1993 -
Journal of the Egyptian Society of... Apr 1991Water samples from four aquatic sites in Egypt were examined for the presence of free-living amoebae. Amoebae were isolated and cultured on 1.5% non-nutrient agar with...
Water samples from four aquatic sites in Egypt were examined for the presence of free-living amoebae. Amoebae were isolated and cultured on 1.5% non-nutrient agar with bacteria. They were studied morphologically and tested for production of flagellated forms, encystment, excystment, nuclear division, temperature tolerance and pathogenicity in young mice (8 - 10 gm). Didascalus thorntoni and Naegleria gruberi were dominant in all surface waters. Naegleria fowleri, Acanthamoeba glebae, A. culbertsoni and A. rhysodes were found in Lower Egypt, while Vahlkampfia avara and V. thornata were found in Upper Egypt. All species tolerated incubation temperatures of up to 36 degrees C except for A. rhysodes which degenerated at 34 degrees C. A. culbertsoni tolerated 38 degrees C but died at 40 degrees C. Amoebae were detected histologically in a necrotic brain tissue from only one mouse which was inoculated with A. culbertsoni.
Topics: Amebiasis; Amoeba; Animals; Egypt; Fresh Water; Male; Mice
PubMed: 2033288
DOI: No ID Found