scholarly journals Temperature-Dependent Parasitic Relationship between Legionella pneumophila and a Free-Living Amoeba (Acanthamoeba castellanii)

2008 ◽  
Vol 74 (14) ◽  
pp. 4585-4588 ◽  
Author(s):  
Akira Ohno ◽  
Naoyuki Kato ◽  
Ryota Sakamoto ◽  
Soichiro Kimura ◽  
Keizo Yamaguchi
Keyword(s):  
Legionella Pneumophila ◽  
Low Temperatures ◽  
Acanthamoeba Castellanii ◽  
Temperature Dependent ◽  
Free Living ◽  
Free Living Amoeba ◽  
Effects Of Temperature ◽  
Number Of Bacteria

ABSTRACT We analyzed the effects of temperature on the interaction of Legionella pneumophila with Acanthamoeba castellanii. At <20°C, overexpression of type 1 metacaspase, a stimulator of A. castellanii encystation, was associated with a reduced number of bacteria within amoeba. At low temperatures, A. castellanii seems to eliminate L. pneumophila by encystation and digestion.

scholarly journals Mitigation of Expression of Virulence Genes in Legionella pneumophila Internalized in the Free-Living Amoeba Willaertia magna C2c Maky

Pathogens ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 447 ◽  
Author(s):  
Rayane Mouh Mameri ◽  
Jacques Bodennec ◽  
Laurent Bezin ◽  
Sandrine Demanèche
Keyword(s):  
Gene Expression ◽  
Legionella Pneumophila ◽  
Virulence Genes ◽  
Natural Habitat ◽  
Acanthamoeba Castellanii ◽  
Severe Form ◽  
Aquatic Environments ◽  
Free Living ◽  
Intracellular Parasites ◽  
Free Living Amoeba

Legionella pneumophila is a human pathogen responsible for a severe form of pneumonia named Legionnaire disease. Its natural habitat is aquatic environments, being in a free state or intracellular parasites of free-living amoebae, such as Acanthamoeba castellanii. This pathogen is able to replicate within some amoebae. Willaertia magna C2c Maky, a non-pathogenic amoeba, was previously demonstrated to resist to L. pneumophila and even to be able to eliminate the L. pneumophila strains Philadelphia, Lens, and Paris. Here, we studied the induction of seven virulence genes of three L. pneumophila strains (Paris, Philadelphia, and Lens) within W. magna C2c Maky in comparison within A. castellanii and with the gene expression level of L. pneumophila strains alone used as controls. We defined a gene expression-based virulence index to compare easily and without bias the transcript levels in different conditions and demonstrated that W. magna C2c Maky did not increase the virulence of L. pneumophila strains in contrast to A. castellanii. These results confirmed the non-permissiveness of W. magna C2c Maky toward L. pneumophila strains.

scholarly journals Legionella pneumophila Contains a Type II General Secretion Pathway Required for Growth in Amoebae as Well as for Secretion of the Msp Protease

1999 ◽  
Vol 67 (7) ◽  
pp. 3662-3666 ◽  
Author(s):  
Laura M. Hales ◽  
Howard A. Shuman
Keyword(s):  
Legionella Pneumophila ◽  
Acanthamoeba Castellanii ◽  
Gram Negative Bacteria ◽  
Type Ii ◽  
Free Living ◽  
Gram Negative ◽  
Secretion Pathway ◽  
Free Living Amoeba ◽  
Substitution Mutation

ABSTRACT We report the identification of a set of Legionella pneumophila genes that encode products with homology to proteins of the type II general secretion pathway of gram-negative bacteria. A strain containing a deletion-substitution mutation of two of these genes was unable to secrete the Msp protease. This strain was unable to multiply within the free-living amoeba Acanthamoeba castellanii yet was able to kill HL-60-derived macrophages. Because Msp is not required for growth in amoebae, other proteins which are important for growth in amoebae are likely secreted by this pathway.

Impact of inter-amoebic phagocytosis on the L. pneumophila growth

2020 ◽  
Vol 367 (18) ◽  
Author(s):  
Rafik Dey ◽  
Mouh Rayane Mameri ◽  
Selena Trajkovic-Bodennec ◽  
Jacques Bodennec ◽  
Pierre Pernin
Keyword(s):  
Legionella Pneumophila ◽  
Acanthamoeba Castellanii ◽  
Pathogenic Bacterium ◽  
Free Living ◽  
Vermamoeba Vermiformis ◽  
Free Living Amoeba ◽  
Hartmannella Vermiformis ◽  
Freshwater Environments

ABSTRACT Free-living amoebae are known to act as replication niches for the pathogenic bacterium Legionella pneumophila in freshwater environments. However, we previously reported that some strains of the Willaertia magna species are more resistant to L. pneumophila infection and differ in their ability to support its growth. From this observation, we hypothesize that L. pneumophila growth in environment could be partly dependent on the composition of amoebic populations and on the possible interactions between different amoebic species. We tested this hypothesis by studying the growth of L. pneumophila and of a permissive free-living amoeba, Vermamoeba vermiformis (formerly named Hartmannella vermiformis), in co-culture with or without other free-living amoebae (Acanthamoeba castellanii and W. magna). We demonstrate the occurrence of inter-amoebic phagocytosis with A. castellanii and W. magna being able to ingest V. vermiformis infected or not infected with L. pneumophila. We also found that L. pneumophila growth is strongly impacted by the permissiveness of each interactive amoeba demonstrating that L. pneumophila proliferation and spread are controlled, at least in part, by inter-amoebic interactions.

scholarly journals Isoniazid Conjugated Magnetic Nanoparticles Loaded with Amphotericin B as a Potent Antiamoebic Agent against Acanthamoeba castellanii

Antibiotics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 276
Author(s):  
Kawish Iqbal ◽  
Sumayah Abdelnasir Osman Abdalla ◽  
Ayaz Anwar ◽  
Kanwal Muhammad Iqbal ◽  
Muhammad Raza Shah ◽  
...  
Keyword(s):  
Magnetic Nanoparticles ◽  
Amphotericin B ◽  
Central Nervous System Infection ◽  
Acanthamoeba Castellanii ◽  
Acanthamoeba Keratitis ◽  
Free Living ◽  
Granulomatous Amoebic Encephalitis ◽  
Nano Drug Delivery ◽  
Free Living Amoeba ◽  
Acanthamoeba Species

The pathogenic free-living amoeba, Acanthamoeba castellanii, is responsible for a rare but deadly central nervous system infection, granulomatous amoebic encephalitis and a blinding eye disease called Acanthamoeba keratitis. Currently, a combination of biguanides, amidine, azoles and antibiotics are used to manage these infections; however, the host cell cytotoxicity of these drugs remains a challenge. Furthermore, Acanthamoeba species are capable of transforming to the cyst form to resist chemotherapy. Herein, we have developed a nano drug delivery system based on iron oxide nanoparticles conjugated with isoniazid, which were further loaded with amphotericin B (ISO-NPs-AMP) to cause potent antiamoebic effects against Acanthamoeba castellanii. The IC50 of isoniazid conjugated with magnetic nanoparticles and loaded with amphotericin B was found to be 45 μg/mL against Acanthamoeba castellanii trophozoites and 50 μg/mL against cysts. The results obtained in this study have promising implications in drug discovery as these nanomaterials exhibited high trophicidal and cysticidal effects, as well as limited cytotoxicity against rat and human cells.

scholarly journals Encystment Induces Down-Regulation of an Acetyltransferase-Like Gene in Acanthamoeba castellanii

Pathogens ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 321 ◽  
Author(s):  
Steven Rolland ◽  
Luce Mengue ◽  
Cyril Noël ◽  
Stéphanie Crapart ◽  
Anne Mercier ◽  
...  
Keyword(s):  
Bioinformatics Analysis ◽  
Acanthamoeba Castellanii ◽  
Acanthamoeba Keratitis ◽  
Free Living ◽  
Adverse Conditions ◽  
Genetic Modifications ◽  
Granulomatous Amoebic Encephalitis ◽  
Free Living Amoeba ◽  
Causative Agents

Acanthamoeba castellanii is a ubiquitous free-living amoeba. Pathogenic strains are causative agents of Acanthamoeba keratitis and granulomatous amoebic encephalitis. In response to adverse conditions, A. castellanii differentiate into cysts, which are metabolically inactive and resistant cells. This process, also named encystment, involves biochemical and genetic modifications that remain largely unknown. This study characterizes the role of the ACA1_384820 Acanthamoeba gene during encystment. This gene encodes a putative N-acetyltransferase, belonging to the Gcn5-related N-acetyltransferase (GNAT) family. We showed that expression of the ACA1_384820 gene was down-regulated as early as two hours after induction of encystment in A. castellanii. Interestingly, overexpression of the ACA1_384820 gene affects formation of cysts. Unexpectedly, the search of homologs of ACA1_384820 in the Eukaryota gene datasets failed, except for some species in the Acanthamoeba genus. Bioinformatics analysis suggested a possible lateral acquisition of this gene from prokaryotic cells. This study enabled us to describe a new Acanthamoeba gene that is down-regulated during encystment.

Temperature acclimation of the caudal photoreceptor response in the crayfish Orconectes rusticus (Girard)

1988 ◽  
Vol 66 (5) ◽  
pp. 1168-1171 ◽  
Author(s):  
Jim H. Belanger
Keyword(s):  
Stimulus Intensity ◽  
Low Temperatures ◽  
Temperature Acclimation ◽  
Thermal Capacity ◽  
Maximum Frequency ◽  
Orconectes Rusticus ◽  
Temperature Dependent ◽  
Caudal Photoreceptor ◽  
Effects Of Temperature ◽  
Nerve Cords

Crayfish (Orconectes rusticus (Girard)) were acclimated for 3 weeks at 5 and 25 °C. The effects of temperature and temperature acclimation on the latency, maximum frequency, and sensitivity to stimulus intensity of the caudal photoreceptor response were examined in isolated abdominal nerve cords. Each of these components was temperature dependent. The maximum frequency of the response showed thermal capacity acclimation but latency did not. Caudal photoreceptor response was insensitive to stimulus intensity at low temperatures but acclimation improved sensitivity.

scholarly journals Investigation of potential pathogenicity of Willaertia magna by investigating the transfer of bacteria pathogenicity genes into its genome

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Issam Hasni ◽  
Nisrine Chelkha ◽  
Emeline Baptiste ◽  
Mouh Rayane Mameri ◽  
Joel Lachuer ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Draft Genome ◽  
Phylogenetic Reconstruction ◽  
Genomic Data ◽  
Cytotoxicity Test ◽  
Protein Homology ◽  
Free Living ◽  
A Genome ◽  
Free Living Amoeba ◽  
Potential Pathogenicity

AbstractWillaertia magna c2c maky is a thermophilic amoeba closely related to the genus Naegleria. This free-living amoeba has the ability to eliminate Legionella pneumophila, which is an amoeba-resisting bacterium living in an aquatic environment. To prevent the proliferation of L. pneumophila in cooling towers, the use of W. magna as natural biocide has been proposed. To provide a better understanding of the W. magna genome, whole-genome sequencing was performed through the study of virulence factors and lateral gene transfers. This amoeba harbors a genome of 36.5 megabases with 18,519 predicted genes. BLASTp analyses reported protein homology between 136 W. magna sequences and amoeba-resistant microorganisms. Horizontal gene transfers were observed based on the basis of the phylogenetic reconstruction hypothesis. We detected 15 homologs of N. fowleri genes related to virulence, although these latter were also found in the genome of N. gruberi, which is a non-pathogenic amoeba. Furthermore, the cytotoxicity test performed on human cells supports the hypothesis that the strain c2c maky is a non-pathogenic amoeba. This work explores the genomic repertory for the first draft genome of genus Willaertia and provides genomic data for further comparative studies on virulence of related pathogenic amoeba, N. fowleri.

Synthesis of diphosphoinositide by a supernatant fraction from Acanthamoeba castellanii

1976 ◽  
Vol 54 (9) ◽  
pp. 772-777 ◽  
Author(s):  
J. Thomas Buckley
Keyword(s):  
Acanthamoeba Castellanii ◽  
Supernatant Fraction ◽  
Two Dimensional ◽  
Free Living ◽  
Low Concentrations ◽  
Free Living Amoeba

Homogenates of the free-living amoeba Acanthamoeba castellanii incorporate phosphate from [γ-32P]ATP into a lipid which co-chromatographs with diphosphoinositide on one- and two-dimensional chromatography. Incorporation into lipids similar in mobility to triphosphoinositide is not detected. The product co-chromatographs with diphosphoinositide whether exogenous phosphatidylinositol or total amoeba lipid is the substrate. The inositide kinase is almost entirely located in the supernatant fraction after centrifugation at 100 000 g. Incorporation of phosphate from [γ-32P]ATP is linear for at least 15 min in the presence of 0.5 mM phosphatidylinositol. The enzyme requires Mg2+ or Mn2+ as well as ATP and it is not affected by low concentrations of Ca2+. The apparent Km for phosphatidylinositol is 2 mM. Both ADP and cAMP inhibit the reaction.

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