-
International Journal of Environmental... Feb 2023Primary amoebic meningoencephalitis (PAM) is a rare but lethal infection of the brain caused by a eukaryote called (). The aim of this review is to consolidate the... (Review)
Review
INTRODUCTION
Primary amoebic meningoencephalitis (PAM) is a rare but lethal infection of the brain caused by a eukaryote called (). The aim of this review is to consolidate the recently published case reports of infection by describing its epidemiology and clinical features with the goal of ultimately disseminating this information to healthcare personnel.
METHODS
A comprehensive literature search was carried out using PubMed, Web of Science, Scopus, and OVID databases until 31 December 2022 by two independent reviewers. All studies from the year 2013 were extracted, and quality assessments were carried out meticulously prior to their inclusion in the final analysis.
RESULTS
A total of 21 studies were selected for qualitative analyses out of the 461 studies extracted. The cases were distributed globally, and 72.7% of the cases succumbed to mortality. The youngest case was an 11-day-old boy, while the eldest was a 75-year-old. Significant exposure to freshwater either from recreational activities or from a habit of irrigating the nostrils preceded onset. The symptoms at early presentation included fever, headache, and vomiting, while late sequalae showed neurological manifestation. An accurate diagnosis remains a challenge, as the symptoms mimic bacterial meningitis. Confirmatory tests include the direct visualisation of the amoeba or the use of the polymerase chain reaction method.
CONCLUSIONS
infection is rare but leads to PAM. Its occurrence is worldwide with a significant risk of fatality. The suggested probable case definition based on the findings is the acute onset of fever, headache, and vomiting with meningeal symptoms following exposure to freshwater within the previous 14 days. Continuous health promotion and health education activities for the public can help to improve knowledge and awareness prior to engagement in freshwater activities.
Topics: Aged; Humans; Male; Amoeba; Brain; Central Nervous System Protozoal Infections; Fever; Headache; Naegleria fowleri
PubMed: 36833715
DOI: 10.3390/ijerph20043021 -
Scientific Reports Apr 2021The Amoebozoa, a group containing predominantly amoeboid unicellular protists has been shown to play an important ecological role in controlling environmental bacteria....
The Amoebozoa, a group containing predominantly amoeboid unicellular protists has been shown to play an important ecological role in controlling environmental bacteria. Amoebozoans not only graze bacteria but also serve as a safe niche for bacterial replication and harbor endosymbiotic bacteria including dangerous human pathogens. Despite their importance, only a few lineages of Amoebozoa have been studied in this regard. In this research, we conducted a comprehensive genomic and transcriptomic study with expansive taxon sampling by including representatives from the three known clades of the Amoebozoa. We used culture independent whole culture and single cell genomics/transcriptomics to investigate the association of bacteria with diverse amoebozoans. Relative to current published evidence, we recovered the largest number of bacterial phyla (64) and human pathogen genera (51) associated with the Amoebozoa. Using single cell genomics/transcriptomics we were able to determine up to 24 potential endosymbiotic bacterial phyla, some potentially endosymbionts. This includes the majority of multi-drug resistant pathogens designated as major public health threats. Our study demonstrates amoebozoans are associated with many more phylogenetically diverse bacterial phyla than previously recognized. It also shows that all amoebozoans are capable of harboring far more dangerous human pathogens than presently documented, making them of primal public health concern.
Topics: Amoeba; Amoebozoa; Bacteria; Genomics; Phylogeny
PubMed: 33850182
DOI: 10.1038/s41598-021-87192-0 -
Molecular Biology and Evolution Sep 2017Amoebozoa is the eukaryotic supergroup sister to Obazoa, the lineage that contains the animals and Fungi, as well as their protistan relatives, and the breviate and...
Amoebozoa is the eukaryotic supergroup sister to Obazoa, the lineage that contains the animals and Fungi, as well as their protistan relatives, and the breviate and apusomonad flagellates. Amoebozoa is extraordinarily diverse, encompassing important model organisms and significant pathogens. Although amoebozoans are integral to global nutrient cycles and present in nearly all environments, they remain vastly understudied. We present a robust phylogeny of Amoebozoa based on broad representative set of taxa in a phylogenomic framework (325 genes). By sampling 61 taxa using culture-based and single-cell transcriptomics, our analyses show two major clades of Amoebozoa, Discosea, and Tevosa. This phylogeny refutes previous studies in major respects. Our results support the hypothesis that the last common ancestor of Amoebozoa was sexual and flagellated, it also may have had the ability to disperse propagules from a sporocarp-type fruiting body. Overall, the main macroevolutionary patterns in Amoebozoa appear to result from the parallel losses of homologous characters of a multiphase life cycle that included flagella, sex, and sporocarps rather than independent acquisition of convergent features.
Topics: Amoeba; Amoebozoa; Animals; Biological Evolution; Eukaryota; Evolution, Molecular; Fungi; Gene Library; Invertebrates; Phylogeny; Sequence Analysis, DNA
PubMed: 28505375
DOI: 10.1093/molbev/msx162 -
Nucleic Acids Research Jan 2011AmoebaDB (http://AmoebaDB.org) and MicrosporidiaDB (http://MicrosporidiaDB.org) are new functional genomic databases serving the amoebozoa and microsporidia research...
AmoebaDB (http://AmoebaDB.org) and MicrosporidiaDB (http://MicrosporidiaDB.org) are new functional genomic databases serving the amoebozoa and microsporidia research communities, respectively. AmoebaDB contains the genomes of three Entamoeba species (E. dispar, E. invadens and E. histolityca) and microarray expression data for E. histolytica. MicrosporidiaDB contains the genomes of Encephalitozoon cuniculi, E. intestinalis and E. bieneusi. The databases belong to the National Institute of Allergy and Infectious Diseases (NIAID) funded EuPathDB (http://EuPathDB.org) Bioinformatics Resource Center family of integrated databases and assume the same architectural and graphical design as other EuPathDB resources such as PlasmoDB and TriTrypDB. Importantly they utilize the graphical strategy builder that affords a database user the ability to ask complex multi-data-type questions with relative ease and versatility. Genomic scale data can be queried based on BLAST searches, annotation keywords and gene ID searches, GO terms, sequence motifs, protein characteristics, phylogenetic relationships and functional data such as transcript (microarray and EST evidence) and protein expression data. Search strategies can be saved within a user's profile for future retrieval and may also be shared with other researchers using a unique strategy web address.
Topics: Databases, Genetic; Encephalitozoon; Entamoeba; Genome, Fungal; Genome, Protozoan; Genomics
PubMed: 20974635
DOI: 10.1093/nar/gkq1006 -
Antimicrobial Agents and Chemotherapy Jun 2022Infection with pathogenic free-living amoebae, including Naegleria fowleri, spp., and Balamuthia mandrillaris, can lead to life-threatening illnesses, primarily because...
Infection with pathogenic free-living amoebae, including Naegleria fowleri, spp., and Balamuthia mandrillaris, can lead to life-threatening illnesses, primarily because of catastrophic central nervous system involvement. Efficacious treatment options for these infections are lacking, and the mortality rate due to infection is high. Previously, we evaluated the N. fowleri glucokinase (Glck) as a potential target for therapeutic intervention, as glucose metabolism is critical for viability. Here, we extended these studies to the glucokinases from two other pathogenic free-living amoebae, including Acanthamoeba castellanii (Glck) and (Glck). While these enzymes are similar (49.3% identical at the amino acid level), they have distinct kinetic properties that distinguish them from each other. For ATP, Glck and Glck have apparent values of 472.5 and 41.0 μM, while Homo sapiens Glck (Glck) has a value of 310 μM. Both parasite enzymes also have a higher apparent affinity for glucose than the human counterpart, with apparent values of 45.9 μM (Glck) and 124 μM (Glck) compared to ~8 mM for Glck. Additionally, Glck and Glck differ from each other and other Glcks in their sensitivity to small molecule inhibitors, suggesting that inhibitors with pan-amoebic activity could be challenging to generate.
Topics: Acanthamoeba; Amebiasis; Amoeba; Balamuthia mandrillaris; Glucokinase; Humans; Naegleria fowleri
PubMed: 35604214
DOI: 10.1128/aac.02373-21 -
Folia Microbiologica Oct 2021Acanthamoeba is known to interact with a plethora of microorganisms such as bacteria, fungi and viruses. In these interactions, the amoebae can be predatory in nature,... (Review)
Review
Acanthamoeba is known to interact with a plethora of microorganisms such as bacteria, fungi and viruses. In these interactions, the amoebae can be predatory in nature, transmission vehicle or an incubator. Amoebae consume microorganisms, especially bacteria, as food source to fulfil their nutritional needs by taking up bacteria through phagocytosis and lysing them in phagolysosomes and hence play an eminent role in the regulation of bacterial density in the nature and accountable for eradication of around 60% of the bacterial population in the environment. Acanthamoeba can also act as a "Trojan horse" for microbial transmission in the environment. Additionally, Acanthamoeba may serve as an incubator-like reservoir for microorganisms, including those that are pathogenic to humans, where the microorganisms use amoebae's defences to resist harsh environment and evade host defences and drugs, whilst growing in numbers inside the amoebae. Furthermore, amoebae can also be used as a "genetic melting pot" where exchange of genes as well as adaptation of microorganisms, leading to higher pathogenicity, may arise. Here, we describe bacteria, fungi and viruses that are known to interact with Acanthamoeba spp.
Topics: Acanthamoeba; Bacterial Physiological Phenomena; Fungi; Host Microbial Interactions; Virus Physiological Phenomena
PubMed: 34145552
DOI: 10.1007/s12223-021-00889-7 -
Clinical Microbiology Reviews Jul 2002Free-living amebas are widely distributed in soil and water, particularly members of the genera Acanthamoeba and NAEGLERIA: Since the early 1960s, they have been... (Review)
Review
Free-living amebas are widely distributed in soil and water, particularly members of the genera Acanthamoeba and NAEGLERIA: Since the early 1960s, they have been recognized as opportunistic human pathogens, capable of causing infections of the central nervous system (CNS) in both immunocompetent and immunocompromised hosts. Naegleria is the causal agent of a fulminant CNS condition, primary amebic meningoencephalitis; Acanthamoeba is responsible for a more chronic and insidious infection of the CNS termed granulomatous amebic encephalitis, as well as amebic keratitis. Balamuthia sp. has been recognized in the past decade as another ameba implicated in CNS infections. Cultivation of these organisms in vitro provides the basis for a better understanding of the biology of these amebas, as well as an important means of isolating and identifying them from clinical samples. Naegleria and Acanthamoeba can be cultured axenically in cell-free media or on tissue culture cells as feeder layers and in cultures with bacteria as a food source. Balamuthia, which has yet to be isolated from the environment, will not grow on bacteria. Instead, it requires tissue culture cells as feeder layers or an enriched cell-free medium. The recent identification of another ameba, Sappinia diploidea, suggests that other free-living forms may also be involved as causal agents of human infections.
Topics: Acanthamoeba; Amebiasis; Amoeba; Animals; Culture Media; Humans; Mice; Naegleria; Opportunistic Infections; Parasitology
PubMed: 12097243
DOI: 10.1128/CMR.15.3.342-354.2002 -
Biochimie May 2014The mitochondria have arisen as a consequence of endosymbiosis of an ancestral α-proteobacterium with a methane-producing archae. The main function of the canonical... (Review)
Review
The mitochondria have arisen as a consequence of endosymbiosis of an ancestral α-proteobacterium with a methane-producing archae. The main function of the canonical aerobic mitochondria include ATP generation via oxidative phosphorylation, heme and phospholipid synthesis, calcium homeostasis, programmed cell death, and the formation of iron-sulfur clusters. Under oxygen-restricted conditions, the mitochondrion has often undergone remarkable reductive alterations of its content and function, leading to the generation of mitochondrion-related organelles (MROs), such as mitosomes, hydrogenosomes, and mithochondrion-like organelles, which are found in a wide range of anaerobic/microaerophilic eukaryotes that include several medically important parasitic protists such as Entamoeba histolytica, Giardia intestinalis, Trichomonas vaginalis, Cryptosporidium parvum, Blastocystis hominis, and Encephalitozoon cuniculi, as well as free-living protists such as Sawyeria marylandensis, Neocallimastix patriciarum, and Mastigamoeba balamuthi. The transformation from canonical aerobic mitochondria to MROs apparently have occurred in independent lineages, and resulted in the diversity of their components and functions. Due to medical and veterinary importance of the MRO-possessing human- and animal-pathogenic protozoa, their genomic, transcriptomic, proteomic, and biochemical evidence has been accumulated. Detailed analyses of the constituents and functions of the MROs in such anaerobic pathogenic protozoa, which reside oxygen-deprived or oxygen-poor environments such as the mammalian intestine and the genital organs, should illuminate the current evolutionary status of the MROs in these organisms, and give insight to environmental constraints that drive the evolution of eukaryotes and their organelles. In this review, we summarize and discuss the diverse metabolic functions and protein transport systems of the MROs from anaerobic parasitic protozoa.
Topics: Alveolata; Amoebozoa; Anaerobiosis; Biodiversity; Biological Evolution; Cryptophyta; Diplomonadida; Gene Expression Regulation; Genome, Mitochondrial; Humans; Mitochondria; Mitochondrial Proteins; Neocallimastix; Phylogeny; Protein Transport
PubMed: 24316280
DOI: 10.1016/j.biochi.2013.11.018 -
BMC Biology Mar 2022Mitochondria and peroxisomes are the two organelles that are most affected during adaptation to microoxic or anoxic environments. Mitochondria are known to transform...
BACKGROUND
Mitochondria and peroxisomes are the two organelles that are most affected during adaptation to microoxic or anoxic environments. Mitochondria are known to transform into anaerobic mitochondria, hydrogenosomes, mitosomes, and various transition stages in between, collectively called mitochondrion-related organelles (MROs), which vary in enzymatic capacity. Anaerobic peroxisomes were identified only recently, and their putatively most conserved function seems to be the metabolism of inositol. The group Archamoebae includes anaerobes bearing both anaerobic peroxisomes and MROs, specifically hydrogenosomes in free-living Mastigamoeba balamuthi and mitosomes in the human pathogen Entamoeba histolytica, while the organelles within the third lineage represented by Pelomyxa remain uncharacterized.
RESULTS
We generated high-quality genome and transcriptome drafts from Pelomyxa schiedti using single-cell omics. These data provided clear evidence for anaerobic derivates of mitochondria and peroxisomes in this species, and corresponding vesicles were tentatively identified in electron micrographs. In silico reconstructed MRO metabolism harbors respiratory complex II, electron-transferring flavoprotein, a partial TCA cycle running presumably in the reductive direction, pyruvate:ferredoxin oxidoreductase, [FeFe]-hydrogenases, a glycine cleavage system, a sulfate activation pathway, and an expanded set of NIF enzymes for iron-sulfur cluster assembly. When expressed in the heterologous system of yeast, some of these candidates localized into mitochondria, supporting their involvement in the MRO metabolism. The putative functions of P. schiedti peroxisomes could be pyridoxal 5'-phosphate biosynthesis, amino acid and carbohydrate metabolism, and hydrolase activities. Unexpectedly, out of 67 predicted peroxisomal enzymes, only four were also reported in M. balamuthi, namely peroxisomal processing peptidase, nudix hydrolase, inositol 2-dehydrogenase, and D-lactate dehydrogenase. Localizations in yeast corroborated peroxisomal functions of the latter two.
CONCLUSIONS
This study revealed the presence and partially annotated the function of anaerobic derivates of mitochondria and peroxisomes in P. schiedti using single-cell genomics, localizations in yeast heterologous systems, and transmission electron microscopy. The MRO metabolism resembles that of M. balamuthi and most likely reflects the state in the common ancestor of Archamoebae. The peroxisomal metabolism is strikingly richer in P. schiedti. The presence of myo-inositol 2-dehydrogenase in the predicted peroxisomal proteome corroborates the situation in other Archamoebae, but future experimental evidence is needed to verify additional functions of this organelle.
Topics: Amoeba; Anaerobiosis; Archamoebae; Genomics; Humans; Mitochondria; Peroxisomes; Saccharomyces cerevisiae
PubMed: 35227266
DOI: 10.1186/s12915-022-01247-w -
Nucleic Acids Research Apr 2024MicroRNAs (miRNAs) are important and ubiquitous regulators of gene expression in both plants and animals. They are thought to have evolved convergently in these lineages...
MicroRNAs (miRNAs) are important and ubiquitous regulators of gene expression in both plants and animals. They are thought to have evolved convergently in these lineages and hypothesized to have played a role in the evolution of multicellularity. In line with this hypothesis, miRNAs have so far only been described in few unicellular eukaryotes. Here, we investigate the presence and evolution of miRNAs in Amoebozoa, focusing on species belonging to Acanthamoeba, Physarum and dictyostelid taxonomic groups, representing a range of unicellular and multicellular lifestyles. miRNAs that adhere to both the stringent plant and animal miRNA criteria were identified in all examined amoebae, expanding the total number of protists harbouring miRNAs from 7 to 15. We found conserved miRNAs between closely related species, but the majority of species feature only unique miRNAs. This shows rapid gain and/or loss of miRNAs in Amoebozoa, further illustrated by a detailed comparison between two evolutionary closely related dictyostelids. Additionally, loss of miRNAs in the Dictyostelium discoideum drnB mutant did not seem to affect multicellular development and, hence, demonstrates that the presence of miRNAs does not appear to be a strict requirement for the transition from uni- to multicellular life.
Topics: Amoebozoa; Dictyostelium; MicroRNAs; Phylogeny; Evolution, Molecular; RNA, Protozoan; Conserved Sequence; RNA Interference
PubMed: 38375870
DOI: 10.1093/nar/gkae109