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The Korean Journal of Parasitology Dec 2003A new species of Acanthamoeba was isolated from a freshwater fish in Korea and tentatively named Acanthamoeba sp. YM-4 (Korean isolate YM-4). The trophozoites were...
A new species of Acanthamoeba was isolated from a freshwater fish in Korea and tentatively named Acanthamoeba sp. YM-4 (Korean isolate YM-4). The trophozoites were 11.0-23.0 micrometer in length and had hyaline filamentous projections. Cysts were similar to those of A. culbertsoni and A. royreba, which were previously designated as Acanthamoeba group III. Acanthamoeba YM-4 can survive at 40 degrees C, and its generation time was 19.6 hr, which was longer than that of A. culbertsoni. In terms of the in vitro cytotoxicity of lysates, Acanthamoeba YM-4 was weaker than A. culbertsoni, but stronger than A. polyphaga. On the basis of the mortality of experimentally infected mice, Acanthamoeba YM-4 was found to be highly virulent. The isoenzymes profile of Acanthamoeba YM-4 was similar to that of A. royreba. An anti-Acanthamoeba YM-4 monoclonal antibody, McAY7, was found to react only with Acanthamoeba YM-4, and not with A. culbertsoni. Random amplified polymorphic DNA marker analysis and RFLP analysis of mitochondrial DNA and of 18S small subunit ribosomal RNA, placed Acanthamoeba YM-4 in a separate cluster on the basis of phylogenetic distances. Thus the Acanthamoeba Korean isolate YM-4 was identified as a new species, and assigned as Acanthamoeba sohi.
Topics: Acanthamoeba; Amebiasis; Animals; DNA, Mitochondrial; DNA, Protozoan; Fish Diseases; Gills; Goldfish; Korea; Mice; Phylogeny; Polymorphism, Restriction Fragment Length; RNA, Ribosomal, 18S; Random Amplified Polymorphic DNA Technique; Virulence
PubMed: 14699258
DOI: 10.3347/kjp.2003.41.4.181 -
Investigative Ophthalmology & Visual... Mar 2008Acanthamoebae provoke a vision-threatening corneal infection known as Acanthamoeba keratitis (AK). It is thought that Acanthamoeba-specific IgA antibodies present in...
PURPOSE
Acanthamoebae provoke a vision-threatening corneal infection known as Acanthamoeba keratitis (AK). It is thought that Acanthamoeba-specific IgA antibodies present in mucosal secretions such as human tears, milk, and saliva provide protection against infection by inhibiting the adhesion of parasites to host cells. The goal of the present study was to determine whether human mucosal secretions have the potential to provide protection against the Acanthamoeba-induced cytopathic effect (CPE) by an additional mechanism that is independent of IgA.
METHODS
Breast milk was used as a model of human mucosal secretions. In vitro CPE assays were used to examine the CPE inhibitory effect of IgA-depleted milk and various milk fractions obtained by gel filtration. The activity of amebic proteinases was examined by zymography.
RESULTS
IgA-depleted milk inhibited the Acanthamoeba-induced CPE in a concentration-dependent manner. Milk proteins were separated into four major fractions (F1-F4) by gel filtration. Of these four fractions, CPE inhibitory activity was detected largely in fraction F3. In contrast, fractions F1, F2, and F4 lacked CPE inhibitory activity. Moreover, fraction F3, but not F1, F2, or F4, inhibited amebic proteinases.
CONCLUSIONS
These data, in conjunction with published findings showing that amebic proteinases are responsible for the induction of Acanthamoeba CPE, led us to propose that human mucosal secretions have the potential to provide protection against Acanthamoeba-induced CPE by an additional mechanism that is independent of IgA and that involves the inhibition of cytotoxic proteinases of amebae.
Topics: Acanthamoeba; Animals; Cell Survival; Cells, Cultured; Chromatography, Gel; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Epithelium, Corneal; Female; Humans; Immunoglobulin A, Secretory; Microscopy, Phase-Contrast; Milk Proteins; Milk, Human; Molecular Weight; Protozoan Proteins; Rabbits
PubMed: 18326724
DOI: 10.1167/iovs.07-1130 -
Experimental Parasitology Sep 2010Three different cell lines (murine macrophages, HeLa and osteosarcoma cells) were assayed in order to check for the manifestation of the cytopathic effects of three...
Three different cell lines (murine macrophages, HeLa and osteosarcoma cells) were assayed in order to check for the manifestation of the cytopathic effects of three strains of Acanthamoeba recently isolated in our laboratory from contact lens cases: CLC-16, CLC-41.r and CLC-51-l. Adhesion and cytotoxicity assays were carried out with these strains and the type strain Acanthamoeba castellanii Neff as a control. Briefly, the ability of these amoebae to bind to the three cell lines was calculated and supernatants were examined for cytotoxicity by measuring lactate dehydrogenase released as an estimate of cytotoxicity using a commercial detection kit. The three strains showed high adhesion and cytotoxicity levels when tested in the three cell lines. This study demonstrates the ability of these amoebae to degrade any of the tested cell lines. To the best of our knowledge, this is the first report of the in vitro effects of acanthamoebae on osteosarcoma cells.
Topics: Acanthamoeba; Animals; Cell Adhesion; Cell Line; Cell Line, Tumor; HeLa Cells; Humans; L-Lactate Dehydrogenase; Macrophages; Mice; Osteosarcoma
PubMed: 19857490
DOI: 10.1016/j.exppara.2009.10.011 -
Journal of Medical Microbiology Aug 2005The majority of the keratitis-causing Acanthamoeba isolates are genotype T4. In an attempt to determine whether predominance of T4 isolates in Acanthamoeba keratitis is...
The majority of the keratitis-causing Acanthamoeba isolates are genotype T4. In an attempt to determine whether predominance of T4 isolates in Acanthamoeba keratitis is due to greater virulence or greater prevalence of this genotype, Acanthamoeba genotypes were determined for 13 keratitis isolates and 12 environmental isolates from Iran. Among 13 clinical isolates, eight (61.5%) belonged to T4, two (15.3%) belonged to T3 and three (23%) belonged to the T2 genotype. In contrast, the majority of 12 environmental isolates tested in the present study belonged to T2 (7/12, 58.3%), followed by 4/12 T4 isolates (33.3%). In addition, the genotypes of six new Acanthamoeba isolates from UK keratitis cases were determined. Of these, five (83.3%) belonged to T4 and one was T3 (16.6%), supporting the expected high frequency of T4 in Acanthamoeba keratitis. In total, the genotypes of 24 Acanthamoeba keratitis isolates from the UK and Iran were determined. Of these, 17 belonged to T4 (70.8%), three belonged to T2 (12.5%), three belonged to T3 (12.5%) and one belonged to T11 (4.1%), confirming that T4 is the predominant genotype (S2=4.167; P=0.0412) in Acanthamoeba keratitis.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Animals; Genotype; Iran; RNA, Ribosomal, 18S; Sequence Analysis, DNA; United Kingdom
PubMed: 16014429
DOI: 10.1099/jmm.0.45970-0 -
Parasites & Vectors Aug 2016Acanthamoeba spp. are free-living ubiquitous protozoans capable of causing Acanthamoeba meningitis/meningoencephalitis (AME) of the central nervous system in humans....
BACKGROUND
Acanthamoeba spp. are free-living ubiquitous protozoans capable of causing Acanthamoeba meningitis/meningoencephalitis (AME) of the central nervous system in humans. Acanthamoeba spp. are divided into 20 different genotypes (T1-T20) on the basis of variation in nucleotide sequences of the 18S rRNA gene. The objective of this study was to identify the genotypes of Acanthamoeba spp. in patients of Acanthamoeba meningitis/meningoencephalitis (AME) using 18S rRNA gene-based PCR assay. The present study provides information regarding the involvement of the most prevalent and predominant genotype of Acanthamoeba spp. in Acanthamoeba meningitis/meningoencephalitis infections in India.
METHODS
Cerebrospinal fluid (CSF) was collected from 149 clinically suspected Acanthamoeba meningitis/meningoencephalitis (AME) patients reporting to the outpatient department/causality services of the Neurosciences Centre, AIIMS, New Delhi, India during the past five years. Samples were inoculated onto 2 % non-nutrient agar plates overlaid with E. coli and incubated at 30 °C for 14 days. Among 149 suspected patients, ten were found culture-positive for Acanthamoeba spp. out of which six isolates were established in axenic culture for molecular analysis. DNA was isolated and a PCR assay was performed for amplification of the Diagnostic fragment 3 (DF3) (~280 bp) region of the 18S rRNA gene from axenic culture of six Acanthamoeba spp. isolates. Rns genotyping was performed on the basis of the variation in nucleotide sequences of DF3 region of the 18S rRNA gene.
RESULTS
In the phylogenetic analysis, all of the six Acanthamoeba spp. isolates were found to belong to genotype T4. The sequence homology search for these six isolates in the NCBI databank showed homology with the available strains of Acanthamoeba spp. The newly generated sequences are available in the GenBank database under accession numbers KT004416-KT004421.
CONCLUSIONS
In the present study, genotype T4 was found as the most prevalent and predominant genotype in Acanthamoeba meningitis/ meningoencephalitis infections. Hence further studies are needed to develop optimal therapeutic strategy against Acanthamoeba spp. of genotype T4 to combat against the infections.
Topics: Acanthamoeba; DNA, Protozoan; DNA, Ribosomal; Genotype; Humans; India; Meningitis; Meningoencephalitis; Phylogeny; RNA, Ribosomal, 18S
PubMed: 27507421
DOI: 10.1186/s13071-016-1729-5 -
Acta Microbiologica Et Immunologica... Mar 2013Acanthamoeba species are free-living amoebae that can be found in almost every range of environments. Within this genus, a number of species are recognized as human...
Acanthamoeba species are free-living amoebae that can be found in almost every range of environments. Within this genus, a number of species are recognized as human pathogens, potentially causing Acanthamoeba keratitis, granulomatous amoebic encephalitis, and chronic granulomatous lesions. Soil and water samples were taken from experimental station at Julianna Major of Plant Protection Institute of Centre for Agricultural Research, Hungarian Academy of Sciences (CAR HAS). We detected living Acanthamoeba spp. based on culture-confirmed detection combined with the molecular taxonomic identification method. Living Acanthamoeba spp. were detected in thirteen (65%) samples. The presence of Acanthamoeba spp. in the samples depends significantly on the rhizosphere plants. The most frequently identified living Acanthamoeba genotype was T4 followed by T11, T2/T6 and T17. Genotypes T4 and T11 of Acanthamoeba, are responsible for Acanthamoeba keratitis as well as granulomatous amoebic encephalitis, and should therefore be considered as a potential health risk associated with human activities in the environment.
Topics: Acanthamoeba; Base Sequence; Genotype; Medicago sativa; Molecular Sequence Data; Phylogeny; Rhizosphere; Zea mays
PubMed: 23529297
DOI: 10.1556/AMicr.60.2013.1.4 -
Microbiology Spectrum Apr 2022species are among the most ubiquitous protists that are widespread in soil and water and act as both a replicative niche and vectors for dispersal. They are the most...
species are among the most ubiquitous protists that are widespread in soil and water and act as both a replicative niche and vectors for dispersal. They are the most important human intracellular pathogens, causing keratitis (AK) and severely damaging the human cornea. The sympatric lifestyle within the host and amoeba-resisting microorganisms (ARMs) promotes horizontal gene transfer (HGT). However, the genomic diversity of only A. castellanii and A. polyphaga has been widely studied, and the pathogenic mechanisms remain unknown. Thus, we examined 7 clinically pathogenic strains by comparative genomic, phylogenetic, and rhizome gene mosaicism analyses to explore amoeba-symbiont interactions that possibly contribute to pathogenesis. Genetic characterization and phylogenetic analysis showed differences in functional characteristics between the "open" state of T3 and T4 isolates, which may contribute to the differences in virulence and pathogenicity. Through comparative genomic analysis, we identified potential genes related to virulence, such as metalloprotease, laminin-binding protein, and HSP, that were specific to the genus . Then, analysis of putative sequence trafficking between and Pandoraviruses or Acanthamoeba castellanii medusaviruses provided the best hits with viral genes; among bacteria, Pseudomonas had the most significant numbers. The most parsimonious evolutionary scenarios were between and endosymbionts; nevertheless, in most cases, the scenarios are more complex. In addition, the differences in exchanged genes were limited to the same family. In brief, this study provided extensive data to suggest the existence of HGT between and ARMs, explaining the occurrence of diseases and challenging Darwin's concept of eukaryotic evolution. has the ability to cause serious blinding keratitis. Although the prevalence of this phenomenon has increased in recent years, our knowledge of the underlying opportunistic pathogenic mechanism maybe remains incomplete. In this study, we highlighted the importance of Pseudomonas in the pathogenesis pathway using comprehensive a whole genomics approach of clinical isolates. The horizontal gene transfer events help to explain how endosymbionts contribute to act as an opportunistic pathogen. Our study opens up several potential avenues for future research on the differences in pathogenicity and interactions among clinical strains.
Topics: Acanthamoeba; Gene Transfer, Horizontal; Genomics; Humans; Phylogeny; Pseudomonas; Virulence Factors
PubMed: 35416714
DOI: 10.1128/spectrum.00025-22 -
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 -
Parasitology International Dec 2010A Thai Acanthamoeba isolate named AS recovered from a corneal scraping of a keratitis patient was genotypically determined as T4. AS trophozoites were used for studying...
A Thai Acanthamoeba isolate named AS recovered from a corneal scraping of a keratitis patient was genotypically determined as T4. AS trophozoites were used for studying Acanthamoeba-induced apoptosis in mouse neuroblastoma NA cells during in vitro co-cultivation. The Acanthamoeba-exposed NA cells showed signs of apoptosis including cell shrinkage, nuclear condensation and DNA fragmentation. The effect was confirmed by DNA laddering electrophoresis. Involvement of caspase enzymes and mitochondrial pro- and anti-apoptotic proteins (Bax and Bcl-2) in AS-induced apoptosis was determined. The use of Z-VAD-FMK, a pan-caspase inhibitor, significantly reduced the apoptotic effect, while Bax/Bcl-2 ratio analysis showed a significant increase in the expression of apoptotic proteins in AS-exposed NA cells. These results strongly indicated that apoptosis induced by AS trophozoites is caspase-dependent and is mediated by over-expression of pro-apoptotic proteins in the mitochondrial pathway. This is the first report on the role of Bax in mediating apoptosis induced by Acanthamoeba.
Topics: Acanthamoeba; Animals; Apoptosis; Caspase Inhibitors; Caspases; Cell Line, Tumor; Genotype; Humans; Mice; Molecular Sequence Data; Neuroblastoma; Proto-Oncogene Proteins c-bcl-2; Sequence Analysis, DNA; Thailand; Trophozoites; bcl-2-Associated X Protein
PubMed: 20601106
DOI: 10.1016/j.parint.2010.06.007 -
Annals of Parasitology 2019Acanthamoeba spp. are free-living amoeba commonly found in environmental sources such as soil, water, and dust. This ubiquitous amoeba is the causative agent of amoebic...
Acanthamoeba spp. are free-living amoeba commonly found in environmental sources such as soil, water, and dust. This ubiquitous amoeba is the causative agent of amoebic keratitis (AK) and encephalitis. The present study aimed to investigate the presence of Acanthamoeba spp. in the water sources of Kermanshah city, Iran. Sixty water samples were taken from different localities of Kermanshah including agricultural canals, rivers, and swimming pools. Filtration and cultivation were carried out on non-nutrient agar medium (NNA). The axenic cultivation was performed for all of the positive isolates. PCR analysis was performed on positive samples. Sequencing was done for 12 PCR products. Genotypes were identified by blast search and homology analysis. The obtained data were analyzed using Statistical Package for the Social Sciences (SPSS 16) software. Acanthamoeba spp. was found in 46 (76.66%) water samples and amoebae were grown in the TYI-S-33 medium. Sequencing of 12 samples proved that Acanthamoeba belonged to T4 (75%), T2 (8.34%), T5 (8.33%) and T11 (8.33%) genotypes. In this study, Acanthamoeba T4 (75%), T2 (8.34%), T5 (8.33%) and T11 (8.33%) genotypes were isolated from the water of Kermanshah city. Thus, hygiene consideration is recommended to prevent the contamination.
Topics: Acanthamoeba; Fresh Water; Genotype; Iran
PubMed: 32191987
DOI: 10.17420/ap6504.226