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The Science of the Total Environment Sep 2024Free-living amoebae (FLA) such as Acanthamoeba, Balamuthia mandrillaris, Naegleria fowleri and Sappinia pedata are naturally widespread in freshwater, causing rare but...
Free-living amoebae (FLA) such as Acanthamoeba, Balamuthia mandrillaris, Naegleria fowleri and Sappinia pedata are naturally widespread in freshwater, causing rare but fatal and debilitating infections in humans. Although recent studies have shown an increase in infection rates, there is a paucity of epidemiological studies regarding the presence of these emerging pathogens in water. Herein, we studied the diversity and relative abundance of thermophilic FLA in different recreational baths in a tropical climate for 5 years. From 2018 to 2022, a total of 96 water samples were collected from 7 recreational baths (natural, tiled, regularly cleaned or not, and with temperatures ranging from 27 to 40 °C). DNA was extracted from FLA cultivated at 37 °C to detect thermophilic culturable FLA. Metabarcoding studies were conducted through FLA 18S rRNA gene amplicons sequencing; amplicon sequence variants (ASV) were extracted from each sample and taxonomy assigned against PR2 database using dada2 and phyloseq tools. We also searched for Naegleria sp. and N. fowleri using PCR targeting ITS and NFITS genes (respectively) and we quantified them using an optimized most probable number (MPN) method for FLA. Our results showed that differences in FLA diversity and abundance were observed amongst the 7 baths, but without a clear seasonal distribution. Naegleria, Vermamoeba and Stenamoeba were the most represented genera, while the genera Acanthamoeba and Vahlkampfia were mainly found in 2 baths. The MPN values for Naegleria sp. (NT/l) increased between 2018 and 2022, but the MPN values for N. fowleri (NF/l) seemed to decrease. Globally, our results showed that since we cannot establish a seasonal distribution of FLA, the regular presence of FLA (namely Naegleria and Acanthamoeba) in recreational waters can pose a potential threat in terms of neuroinfections as well as Acanthamoeba keratitis. It is thus imperious to perform the regular control of these baths as a preventive health measure.
Topics: Amoeba; Guadeloupe; Environmental Monitoring; Fresh Water; Bathing Beaches
PubMed: 38777057
DOI: 10.1016/j.scitotenv.2024.173318 -
BMJ Case Reports May 2024keratitis (AK) is a rare but potentially sight-threatening complication of corneal collagen crosslinking (CXL) for keratoconus. In this report, we describe an early...
keratitis (AK) is a rare but potentially sight-threatening complication of corneal collagen crosslinking (CXL) for keratoconus. In this report, we describe an early adolescent male who underwent routine CXL for progressive keratoconus in his left eye. Preprocedural left visual acuity (VA) was 6/9. At day 5 postprocedure, multifocal corneal infiltrates were identified. Corneal scrape, bandage contact lens cultures and herpetic and PCR were negative. In vivo, confocal microscopy (IVCM) identified cysts within the corneal stroma. Intensive amoebicidal therapy was initiated, but recovery was complicated by significant inflammation, resulting in widespread aggressive corneal vascularisation necessitating topical steroids and steroid-sparing agents. At 10 months, his left VA was 6/24. This report emphasises the importance of maintaining a high index of suspicion for AK in cases of post-CXL microbial keratitis and highlights the diagnostic value of IVCM, particularly in culture-negative and PCR-negative cases.
Topics: Acanthamoeba Keratitis; Humans; Microscopy, Confocal; Male; Keratoconus; Adolescent; Riboflavin; Collagen; Photosensitizing Agents; Cross-Linking Reagents; Visual Acuity; Cornea; Acanthamoeba; Corneal Stroma
PubMed: 38772872
DOI: 10.1136/bcr-2023-257279 -
European Journal of Protistology Jun 2024Acanthamoeba castellanii (Douglas, 1930) Page, 1967 is the type species of a widespread genus of free-living amoebae, potentially pathogenic for humans and animals. The...
Acanthamoeba castellanii (Douglas, 1930) Page, 1967 is the type species of a widespread genus of free-living amoebae, potentially pathogenic for humans and animals. The Neff strain is one of the most widely used in biological research, serving as a model for both A. castellanii and the whole genus in general. The Neff strain, isolated in California, closely resembles another strain found in France and originally described as a separate species, Acanthamoeba terricola Pussard, 1964, but both were successively synonymized with A. castellanii. Molecular sequence analysis has largely replaced morphological diagnosis for species identification in Acanthamoeba, and rDNA phylogenies show that the Neff strain forms a distinct lineage from that of the type strain of A. castellanii. In this study, we compared the type strain of A. terricola with the Neff strain and A. castellanii, and analysed the available molecular data including new sequences obtained from A. terricola. Here we provide molecular evidence to validate the species A. terricola. The Neff strain is therefore transferred to A. terricola and should no longer be considered as belonging to A. castellanii.
Topics: Phylogeny; Acanthamoeba; DNA, Protozoan; DNA, Ribosomal; Species Specificity; Sequence Analysis, DNA; Molecular Sequence Data; Animals
PubMed: 38772052
DOI: 10.1016/j.ejop.2024.126091 -
Parasitology Research May 2024Domestic dogs and cats can serve as a source of environmental contamination with Toxocara spp. and Blastocystis spp., and this represents a neglected public and...
Domestic dogs and cats can serve as a source of environmental contamination with Toxocara spp. and Blastocystis spp., and this represents a neglected public and veterinary health problem. We assessed the microscopic and molecular prevalence of these species in a locality in Algeria and identified the associated risk factors. The faeces of 225 dogs and 78 cats were collected in Mitidja between March and July 2022. The samples were analysed by coproscopy and by polymerase chain reaction (PCR) targeting the Internal Transcribed Spacer 2 (ITS2) and Small Subunit Ribosomal (SSU-RNA) of T. canis and Blastocystis spp. respectively. The overall microscopic prevalence of Toxocara spp. in dogs and cats was 9.78 ± 1.98% and 12.82 ± 7.42%, respectively. The rate of Blastocystis spp. was 15.11 ± 2.39% and 15.38 ± 4.08% in dogs and cats, respectively while the molecular prevalence of T. canis in dogs was 4.89 ± 1.44% and in cats 1.28 ± 1.27%; the prevalence of Blastocystis spp. was 41.78 ± 3.29% and 34.62 ± 5.39% in dogs and cats, respectively. Phylogenetic and phylogeographic analyses identified the presence of the H1 subtype of T. canis in dogs, and the ST1 subtype of Blastocystis in dogs and cats. Dogs with clinical signs were more likely to be infected with T. canis (OR 6.039, P < 0.05) than healthy dogs. This study demonstrates that dogs and cats are carriers of Toxocara spp. and Blastocystis spp. and are therefore a source of environmental contamination. Veterinarians and human health professionals should work together to implement control strategies as part of a "One Health" approach to improving animal health and reducing the risk of transmission to humans.
Topics: Animals; Dogs; Cats; Algeria; Dog Diseases; Cat Diseases; Toxocariasis; Prevalence; Risk Factors; Blastocystis Infections; Toxocara; Feces; Blastocystis; Male; Female; Polymerase Chain Reaction; Microscopy; Phylogeny
PubMed: 38771352
DOI: 10.1007/s00436-024-08240-y -
ACS Infectious Diseases Jun 2024Primary amoebic meningoencephalitis (PAM) is a rare and fulminant neurodegenerative disease caused by the free-living amoeba . Currently, there is a lack of standardized...
Primary amoebic meningoencephalitis (PAM) is a rare and fulminant neurodegenerative disease caused by the free-living amoeba . Currently, there is a lack of standardized protocols for therapeutic action. In response to the critical need for effective therapeutic agents, we explored the Global Health Priority Box, a collection of 240 compounds provided by the Medicines for Malaria Venture (MMV). From this pool, flucofuron emerged as a promising candidate, exhibiting high efficacy against trophozoites of both strains (ATCC 30808 IC : 2.58 ± 0.64 μM and ATCC 30215 IC: 2.47 ± 0.38 μM), being even active against the resistant cyst stage (IC: 0.88 ± 0.07 μM). Moreover, flucofuron induced diverse metabolic events that suggest the triggering of apoptotic cell death. This study highlights the potential of repurposing medications for treating challenging diseases, such as PAM.
Topics: Naegleria fowleri; Humans; Trophozoites; Antiprotozoal Agents; Drug Repositioning; Apoptosis; Central Nervous System Protozoal Infections; Amebiasis
PubMed: 38757533
DOI: 10.1021/acsinfecdis.4c00062 -
Scientific Reports May 2024The patterns of Formin B and of the Arp2/3 complex formed during mitosis were studied in a mutant of Dictyostelium discoideum that produces multinucleate cells, which...
The patterns of Formin B and of the Arp2/3 complex formed during mitosis were studied in a mutant of Dictyostelium discoideum that produces multinucleate cells, which divide by the ingression of unilateral cleavage furrows. During cytokinesis the cells of this mutant remain spread on a glass surface where they generate a planar pattern based on the sorting-out of actin-binding proteins. During anaphase, Formin B and Arp2/3 became localized to the regions of microtubule asters around the centrosomes; Formin B in particular in the form of round, quite uniformly covered areas. These areas have been shown to be depleted of myosin II and the actin-filament crosslinker cortexillin, and to be avoided by cleavage furrows on their path into the cell.
Topics: Microtubules; Dictyostelium; Mitosis; Microfilament Proteins; Actin-Related Protein 2-3 Complex; Protozoan Proteins; Protein Transport; Cytokinesis; Actins
PubMed: 38755233
DOI: 10.1038/s41598-024-61967-7 -
Experimental Parasitology Jul 2024Acanthamoeba spp., are common free-living amoebae found in nature that can serve as reservoirs for certain microorganisms. The SARS-CoV-2 virus is a newly emerged...
Acanthamoeba spp., are common free-living amoebae found in nature that can serve as reservoirs for certain microorganisms. The SARS-CoV-2 virus is a newly emerged respiratory infection, and the investigation of parasitic infections remains an area of limited research. Given that Acanthamoeba can act as a host for various endosymbiotic microbial pathogens and its pathogenicity assay is not fully understood, this study aimed to identify Acanthamoeba and its bacterial and fungal endosymbionts in patients with chronic respiratory disorders and hospitalized COVID-19 patients in northern Iran. Additionally, a pathogenicity assay was conducted on Acanthamoeba isolates. Urine, nasopharyngeal swab, and respiratory specimens were collected from two groups, and each sample was cultured on 1.5% non-nutrient agar medium. The cultures were then incubated at room temperature and monitored daily for a period of two weeks. Eight Acanthamoeba isolates were identified, and PCR was performed to confirm the presence of amoebae and identify their endosymbionts. Four isolates were found to have bacterial endosymbionts, including Stenotrophomonas maltophilia and Achromobacter sp., while two isolates harbored fungal endosymbionts, including an uncultured fungus and Gloeotinia sp. In the pathogenicity assay, five isolates exhibited a higher degree of pathogenicity compared to the other three. This study provides significant insights into the comorbidity of acanthamoebiasis and COVID-19 on a global scale, and presents the first evidence of Gloeotinia sp. as a fungal endosymbiont. Nevertheless, further research is required to fully comprehend the symbiotic patterns and establish effective treatment protocols.
Topics: Humans; Iran; Acanthamoeba; COVID-19; Symbiosis; SARS-CoV-2; Male; Female; Stenotrophomonas maltophilia; Middle Aged; Adult; Amebiasis; Polymerase Chain Reaction; Aged; Vero Cells; Hospitalization; Chlorocebus aethiops
PubMed: 38754618
DOI: 10.1016/j.exppara.2024.108774 -
MBio Jun 2024Amoebae are environmental predators feeding on bacteria, fungi, and other eukaryotic microbes. Predatory interactions alter microbial communities and impose selective...
UNLABELLED
Amoebae are environmental predators feeding on bacteria, fungi, and other eukaryotic microbes. Predatory interactions alter microbial communities and impose selective pressure toward phagocytic resistance or escape which may, in turn, foster virulence attributes. The ubiquitous fungivorous amoeba has a wide prey spectrum in the fungal kingdom but discriminates against members of the clade, such as and . Here, we show that this prey discrimination among fungi is solely based on the presence of ubiquinone as an essential cofactor for the predator. While the amoeba readily fed on fungi with CoQ presenting longer isoprenyl side chain variants CoQ8-10, such as those from the clade, it failed to proliferate on those with shorter CoQ variants, specifically from the clade (CoQ6). Supplementing non-edible yeast with CoQ9 or CoQ10 rescued the growth , highlighting the importance of a long isoprenyl side chain. Heterologous biosynthesis of CoQ9 in by introducing genes responsible for CoQ9 production from the evolutionary more basic complemented the function of the native CoQ6. The results suggest that the use of CoQ6 among members of the clade might have originated as a predatory escape strategy in fungal lineages and could be retained in organisms that were able to thrive by fermentation.
IMPORTANCE
Ubiquinones (CoQ) are universal electron carriers in the respiratory chain of all aerobic bacteria and eukaryotes. Usually 8-10 isoprenyl units ensure their localization within the lipid bilayer. Members of the clade among fungi are unique in using only 6. The reason for this is unclear. Here we provide evidence that the use of CoQ6 efficiently protects these fungi from predation by the ubiquitous fungivorous amoeba which lacks its own biosynthetic pathway for this vitamin. The amoebae were starving on a diet of CoQ6 yeasts which could be complemented by either the addition of longer CoQs or the genetic engineering of a CoQ9 biosynthetic pathway.
Topics: Ubiquinone; Saccharomyces cerevisiae; Amoeba; Yarrowia; Fungi
PubMed: 38747615
DOI: 10.1128/mbio.00342-24 -
Nature Communications May 2024Greenbeard genetic elements encode rare perceptible signals, signal recognition ability, and altruism towards others that display the same signal. Putative greenbeards...
Greenbeard genetic elements encode rare perceptible signals, signal recognition ability, and altruism towards others that display the same signal. Putative greenbeards have been described in various organisms but direct evidence for all the properties in one system is scarce. The tgrB1-tgrC1 allorecognition system of Dictyostelium discoideum encodes two polymorphic membrane proteins which protect cells from chimerism-associated perils. During development, TgrC1 functions as a ligand-signal and TgrB1 as its receptor, but evidence for altruism has been indirect. Here, we show that mixing wild-type and activated tgrB1 cells increases wild-type spore production and relegates the mutants to the altruistic stalk, whereas mixing wild-type and tgrB1-null cells increases mutant spore production and wild-type stalk production. The tgrB1-null cells cheat only on partners that carry the same tgrC1-allotype. Therefore, TgrB1 activation confers altruism whereas TgrB1 inactivation causes allotype-specific cheating, supporting the greenbeard concept and providing insight into the relationship between allorecognition, altruism, and exploitation.
Topics: Altruism; Chemotaxis; Dictyostelium; Membrane Proteins; Mutation; Protozoan Proteins; Signal Transduction; Spores, Protozoan
PubMed: 38734736
DOI: 10.1038/s41467-024-48380-4 -
Molecules (Basel, Switzerland) May 2024Cellular slime molds are excellent model organisms in the field of cell and developmental biology because of their simple developmental patterns. During our studies on...
Cellular slime molds are excellent model organisms in the field of cell and developmental biology because of their simple developmental patterns. During our studies on the identification of bioactive molecules from secondary metabolites of cellular slime molds toward the development of novel pharmaceuticals, we revealed the structural diversity of secondary metabolites. Cellular slime molds grow by feeding on bacteria, such as and without using medium components. Although changing the feeding bacteria is expected to affect dramatically the secondary metabolite production, the effect of the feeding bacteria on the production of secondary metabolites is not known. Herein, we report the isolation and structure elucidation of clavapyrone () from , intermedipyrone () from , and magnumiol () from . These compounds are not obtained from usual cultural conditions with but obtained from coincubated conditions with spp. The results demonstrate the diversity of the secondary metabolites of cellular slime molds and suggest that widening the range of feeding bacteria for cellular slime molds would increase their application potential in drug discovery.
Topics: Dictyostelium; Pyrones; Pseudomonas; Molecular Structure; Secondary Metabolism
PubMed: 38731634
DOI: 10.3390/molecules29092143