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Acanthamoeba Polyphaga

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Bernard La Scola – One of the best experts on this subject based on the ideXlab platform.

S.n. Smith – One of the best experts on this subject based on the ideXlab platform.

Didier Raoult – One of the best experts on this subject based on the ideXlab platform.

  • Acanthamoeba Polyphaga mimivirus Virophage Seroconversion in Travelers Returning from Laos
    Emerging Infectious Diseases, 2012
    Co-Authors: Philippe Parola, Bernard La Scola, Aurelie Renvoise, Elisabeth Botelho-nevers, Christelle Desnues, Didier Raoult
    Abstract:

    During January 2010, a husband and wife returned from Laos to France with probable parasitic disease. Increased antibodies against an Acanthamoeba Polyphaga mimivirus virophage indicated seroconversion. While in Laos, they had eaten raw fish, a potential source of the virophage. This virophage, associated with giant viruses suspected to cause pneumonia, could be an emerging pathogen.

  • viruses with more than 1 000 genes mamavirus a new Acanthamoeba Polyphaga mimivirus strain and reannotation of mimivirus genes
    Genome Biology and Evolution, 2011
    Co-Authors: Philippe Colson, Didier Raoult, Bernard La Scola, Natalya Yutin, Svetlana A Shabalina, Catherine Robert, Ghislain Fournous, Eugene V Koonin
    Abstract:

    The genome sequence of the Mamavirus, a new Acanthamoeba Polyphaga mimivirus strain, is reported. With 1,191,693 nt in length and 1,023 predicted protein-coding genes, the Mamavirus has the largest genome among the known viruses. The genomes of the Mamavirus and the previously described Mimivirus are highly similar in both the protein-coding genes and the intergenic regions. However, the Mamavirus contains an extra 5′-terminal segment that encompasses primarily disrupted duplicates of genes present elsewhere in the genome. The Mamavirus also has several unique genes including a small regulatory polyA polymerase subunit that is shared with poxviruses. Detailed analysis of the protein sequences of the two Mimiviruses led to a substantial amendment of the functional annotation of the viral genomes.

  • Is Acanthamoeba Polyphaga Mimivirus an Emerging Causative Agent of Pneumonia
    Emerging Infections 9, 2010
    Co-Authors: Philippe Colson, Didier Raoult
    Abstract:

    Acanthamoeba Polyphaga mimivirus (APMV) is the first member of a new family of nucleocytoplasmic large DNA viruses called the Mimiviridae. Another giant virus, named mamavirus, was discovered in 2008 and is considered another APMV strain. Moreover, nosocomially acquired pneumonias account for 10 to 15% of all hospital-acquired infections, and pneumonia is actually the leading cause of nosocomial infection in intensive care units (ICU), where ventilator-associated pneumonias (VAP) are the most frequently observed hospital-acquired infections and are associated with high morbidity and mortality. Mimivirus was one of the agents investigated by serological testing, among other conventional pneumonia agents. Among pneumonia patients with amoeba-associated pathogens, more had seroconversion to mimivirus (5 cases) than to any other pathogen. In addition, mimivirus was second among the four most frequently encountered agents of pneumonia diagnosed with high levels of evidence (3.8%), behind Pseudomonas aeruginosa (4.8%) but before Escherichia coli (1.9%) and Legionella pneumophila (1.4%). It should be noted that only one-third of the therapeutic regimens are effective in pneumonia patients needing ventilators. Serology linked APMV to pneumonia, but infection was documented by PCR in only one patient. current data prompt us to consider APMV and its relatives as biosafety level 2 pathogens and to enforce the respiratory care protocols aimed at limiting exposure to amoeba-associated microorganisms (AAMs).

Steven L. Kelly – One of the best experts on this subject based on the ideXlab platform.

  • Azole antifungal agents to treat the human pathogens Acanthamoeba castellanii and Acanthamoeba Polyphaga through inhibition of sterol 14α-demethylase (CYP51)
    Antimicrobial agents and chemotherapy, 2015
    Co-Authors: David C. Lamb, Andrew G. S. Warrilow, Nicola J. Rolley, Josie E. Parker, W. David Nes, Stephen N. Smith, Diane E. Kelly, Steven L. Kelly
    Abstract:

    In this study, we investigate the amebicidal activities of the pharmaceutical triazole CYP51 inhibitors fluconazole, itraconazole, and voriconazole against Acanthamoeba castellanii and Acanthamoeba Polyphaga and assess their potential as therapeutic agents against Acanthamoeba infections in humans. Amebicidal activities of the triazoles were assessed by in vitro minimum inhibition concentration (MIC) determinations using trophozoites of A. castellanii and A. Polyphaga. In addition, triazole effectiveness was assessed by ligand binding studies and inhibition of CYP51 activity of purified A. castellanii CYP51 (AcCYP51) that was heterologously expressed in Escherichia coli. Itraconazole and voriconazole bound tightly to AcCYP51 (dissociation constant [Kd] of 10 and 13 nM), whereas fluconazole bound weakly (Kd of 2,137 nM). Both itraconazole and voriconazole were confirmed to be strong inhibitors of AcCYP51 activity (50% inhibitory concentrations [IC50] of 0.23 and 0.39 μM), whereas inhibition by fluconazole was weak (IC50, 30 μM). However, itraconazole was 8- to 16-fold less effective (MIC, 16 mg/liter) at inhibiting A. Polyphaga and A. castellanii cell proliferation than voriconazole (MIC, 1 to 2 mg/liter), while fluconazole did not inhibit Acanthamoeba cell division (MIC, >64 mg/liter) in vitro. Voriconazole was an effective inhibitor of trophozoite proliferation for A. castellanii and A. Polyphaga; therefore, it should be evaluated in trials versus itraconazole for controlling Acanthamoeba infections.

  • analysis of Acanthamoeba Polyphaga surface carbohydrate exposure by fitc lectin binding and fluorescence evaluation
    Journal of Applied Microbiology, 2004
    Co-Authors: Edward A. G. Elloway, Richard A. Armstrong, Roger Bird, Steven L. Kelly, S.n. Smith
    Abstract:

    Aims: Characterization of the representative protozoan Acanthamoeba Polyphaga surface carbohydrate exposure by a novel combination of flow cytometry and ligand-receptor analysis. Methods and Results: Trophozoite and cyst morphological forms were exposed to a panel of FITC-lectins. Population fluorescence associated with FITC-lectin binding to Acanthamoebal surface moieties was ascertained by flow cytometry. Increasing concentrations of representative FITC-lectins, saturation binding and determination of K d and relative Bmax values were employed to characterize carbohydrate residue exposure. FITC-lectins specific for N-acetylglucosamine, N-acetylgalactosamine and mannose/glucose were readily bound by trophozoite and cyst surfaces. Minor incremental increases in FITC-lectin concentration resulted in significant differences in surface fluorescence intensity and supported the calculation of ligand-binding determinants, Kd and relative B max, which gave a trophozoite and cyst rank order of lectin affinity and surface receptor presence. Conclusions: Trophozoites and cysts expose similar surface carbohydrate residues, foremost amongst which is N-acetylglucosamine, in varying orientation and availability. Significance and Impact of the Study: The outlined versatile combination of flow cytometry and ligand-receptor analysis allowed the characterization of surface carbohydrate exposure by protozoan morphological forms and in turn will support a valid comparison of carbohydrate exposure by other single-cell protozoa and eucaryotic microbes analysed in the same manner.

  • Analysis of Acanthamoeba Polyphaga surface carbohydrate exposure by FITC–lectin binding and fluorescence evaluation
    Journal of applied microbiology, 2004
    Co-Authors: Edward A. G. Elloway, Richard A. Armstrong, Roger Bird, Steven L. Kelly, S.n. Smith
    Abstract:

    Aims: Characterization of the representative protozoan Acanthamoeba Polyphaga surface carbohydrate exposure by a novel combination of flow cytometry and ligand-receptor analysis. Methods and Results: Trophozoite and cyst morphological forms were exposed to a panel of FITC-lectins. Population fluorescence associated with FITC-lectin binding to Acanthamoebal surface moieties was ascertained by flow cytometry. Increasing concentrations of representative FITC-lectins, saturation binding and determination of K d and relative Bmax values were employed to characterize carbohydrate residue exposure. FITC-lectins specific for N-acetylglucosamine, N-acetylgalactosamine and mannose/glucose were readily bound by trophozoite and cyst surfaces. Minor incremental increases in FITC-lectin concentration resulted in significant differences in surface fluorescence intensity and supported the calculation of ligand-binding determinants, Kd and relative B max, which gave a trophozoite and cyst rank order of lectin affinity and surface receptor presence. Conclusions: Trophozoites and cysts expose similar surface carbohydrate residues, foremost amongst which is N-acetylglucosamine, in varying orientation and availability. Significance and Impact of the Study: The outlined versatile combination of flow cytometry and ligand-receptor analysis allowed the characterization of surface carbohydrate exposure by protozoan morphological forms and in turn will support a valid comparison of carbohydrate exposure by other single-cell protozoa and eucaryotic microbes analysed in the same manner.

Edward A. G. Elloway – One of the best experts on this subject based on the ideXlab platform.

  • analysis of Acanthamoeba Polyphaga surface carbohydrate exposure by fitc lectin binding and fluorescence evaluation
    Journal of Applied Microbiology, 2004
    Co-Authors: Edward A. G. Elloway, Richard A. Armstrong, Roger Bird, Steven L. Kelly, S.n. Smith
    Abstract:

    Aims: Characterization of the representative protozoan Acanthamoeba Polyphaga surface carbohydrate exposure by a novel combination of flow cytometry and ligand-receptor analysis. Methods and Results: Trophozoite and cyst morphological forms were exposed to a panel of FITC-lectins. Population fluorescence associated with FITC-lectin binding to Acanthamoebal surface moieties was ascertained by flow cytometry. Increasing concentrations of representative FITC-lectins, saturation binding and determination of K d and relative Bmax values were employed to characterize carbohydrate residue exposure. FITC-lectins specific for N-acetylglucosamine, N-acetylgalactosamine and mannose/glucose were readily bound by trophozoite and cyst surfaces. Minor incremental increases in FITC-lectin concentration resulted in significant differences in surface fluorescence intensity and supported the calculation of ligand-binding determinants, Kd and relative B max, which gave a trophozoite and cyst rank order of lectin affinity and surface receptor presence. Conclusions: Trophozoites and cysts expose similar surface carbohydrate residues, foremost amongst which is N-acetylglucosamine, in varying orientation and availability. Significance and Impact of the Study: The outlined versatile combination of flow cytometry and ligand-receptor analysis allowed the characterization of surface carbohydrate exposure by protozoan morphological forms and in turn will support a valid comparison of carbohydrate exposure by other single-cell protozoa and eucaryotic microbes analysed in the same manner.

  • Analysis of Acanthamoeba Polyphaga surface carbohydrate exposure by FITC–lectin binding and fluorescence evaluation
    Journal of applied microbiology, 2004
    Co-Authors: Edward A. G. Elloway, Richard A. Armstrong, Roger Bird, Steven L. Kelly, S.n. Smith
    Abstract:

    Aims: Characterization of the representative protozoan Acanthamoeba Polyphaga surface carbohydrate exposure by a novel combination of flow cytometry and ligand-receptor analysis. Methods and Results: Trophozoite and cyst morphological forms were exposed to a panel of FITC-lectins. Population fluorescence associated with FITC-lectin binding to Acanthamoebal surface moieties was ascertained by flow cytometry. Increasing concentrations of representative FITC-lectins, saturation binding and determination of K d and relative Bmax values were employed to characterize carbohydrate residue exposure. FITC-lectins specific for N-acetylglucosamine, N-acetylgalactosamine and mannose/glucose were readily bound by trophozoite and cyst surfaces. Minor incremental increases in FITC-lectin concentration resulted in significant differences in surface fluorescence intensity and supported the calculation of ligand-binding determinants, Kd and relative B max, which gave a trophozoite and cyst rank order of lectin affinity and surface receptor presence. Conclusions: Trophozoites and cysts expose similar surface carbohydrate residues, foremost amongst which is N-acetylglucosamine, in varying orientation and availability. Significance and Impact of the Study: The outlined versatile combination of flow cytometry and ligand-receptor analysis allowed the characterization of surface carbohydrate exposure by protozoan morphological forms and in turn will support a valid comparison of carbohydrate exposure by other single-cell protozoa and eucaryotic microbes analysed in the same manner.