Identification and ultrastructural characterization of Acanthamoeba bacterial endocytobionts belonging to the Alphaproteobacteria class

Chan, Li Li; Mak, Joon Wah; Ambu, Stephen; Chong, Pei Yee

doi:10.1371/journal.pone.0204732

Cited by 14 publications

(12 citation statements)

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“…PCR (33/43, 76.7%), gene sequencing (30/43, 69.8%), and microscopy (transmission and scanning electron microscopy, confocal laser scanning, and phase-contrast microscopy) (29/43, 67.4%) were the most commonly used techniques to identify the amoeba and intracellular microbes, followed by fluorescence in situ hybridization (12/43, 27.9%) ( Figure S1 ) [ 21 , 49 , 52 , 53 , 62 , 68 , 74 , 77 ]. Two studies observed intracellular bacteria in Acanthamoeba cysts [ 52 , 80 ].…”

Section: Resultsmentioning

confidence: 99%

“…The use of bacteria, even dead bacteria, to grow Acanthamoeba trophozoites could potentially affect the types of intracellular microbes that can be grown from the Acanthamoeba . Twelve studies have examined the presence of intracellular bacteria using axenic culture [ 22 , 43 , 46 , 51 , 66 , 69 , 71 , 72 , 78 , 79 , 80 ], where three studies [ 58 , 71 , 72 ] have used antibiotics (streptomycin, penicillin, and gentamicin) in PYG to grow amoebae axenically, 18 studies have used NNA with live/inactivated or killed bacteria ( E. coli, E. cloacae, S. cerevisiae, E. aerogenes ), followed by axenic culture, to recover the intracellular microbes harbouring Acanthamoeba [ 20 , 21 , 49 , 53 , 56 , 57 , 59 , 61 , 62 , 64 , 65 , 67 , 68 , 75 , 76 , 77 , 81 ] and antibiotics (penicillin, streptomycin, ampicillin, and amphotericin B) were added in culture media (NNA, TSB, SCGYE, PYG) to make the growth contamination free and axenic in another seven studies [ 40 , 42 , 45 , 47 , 48 , 52 , 70 ] ( Table 2 ). Some studies have used PYG without inorganic salts to maintain axenic growth of amoeba [ 69 , 72 ].…”

Section: Resultsmentioning

confidence: 99%

“…The most commonly reported genotypes of Acanthamoeba are T4 [ 11 , 52 , 57 , 64 , 73 , 74 , 76 , 77 , 81 ], followed by T3 [ 58 , 69 , 71 , 72 , 75 , 80 ], T5 [ 69 , 72 , 80 , 110 ], and T2 [ 33 , 58 , 62 , 74 ] ( Figure S2 ). A. polyphaga was detected in eight studies [ 20 , 33 , 47 , 53 , 54 , 65 , 70 , 78 ] and A. castellani was observed in five studies [ 20 , 33 , 56 , 66 , 70 ].…”

Section: Resultsmentioning

confidence: 99%

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A Systematic Review of Intracellular Microorganisms within Acanthamoeba to Understand Potential Impact for Infection

et al. 2021

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Acanthamoeba, an opportunistic pathogen is known to cause an infection of the cornea, central nervous system, and skin. Acanthamoeba feeds different microorganisms, including potentially pathogenic prokaryotes; some of microbes have developed ways of surviving intracellularly and this may mean that Acanthamoeba acts as incubator of important pathogens. A systematic review of the literature was performed in order to capture a comprehensive picture of the variety of microbial species identified within Acanthamoeba following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Forty-three studies met the inclusion criteria, 26 studies (60.5%) examined environmental samples, eight (18.6%) studies examined clinical specimens, and another nine (20.9%) studies analysed both types of samples. Polymerase chain reaction (PCR) followed by gene sequencing was the most common technique used to identify the intracellular microorganisms. Important pathogenic bacteria, such as E. coli, Mycobacterium spp. and P. aeruginosa, were observed in clinical isolates of Acanthamoeba, whereas Legionella, adenovirus, mimivirus, and unidentified bacteria (Candidatus) were often identified in environmental Acanthamoeba. Increasing resistance of Acanthamoeba associated intracellular pathogens to antimicrobials is an increased risk to public health. Molecular-based future studies are needed in order to assess the microbiome residing in Acanthamoeba, as a research on the hypotheses that intracellular microbes can affect the pathogenicity of Acanthamoeba infections.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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A Systematic Review of Intracellular Microorganisms within Acanthamoeba to Understand Potential Impact for Infection

et al. 2021

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“…The term "endocytobionts" refers to bacteria, fungi, small protozoa or viruses, which are able to reside permanently or transiently in the cellular milieu of the amoebae [21]. Cellulose-rich wall of Acanthamoeba protects their endocytobionts from external toxins, involving factors produced by immune cells.…”

Section: Introductionmentioning

confidence: 99%

Acanthamoeba – pathogen and vector of highly pathogenic bacteria strains to healthy and immunocompromised individuals

Borecka¹,

Bielawska-Drózd²,

Skotarczak³

et al. 2020

cejoi

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Acanthamoeba is a free-living protist pathogen, which is present in every place on earth. 50 to 100 percent of the adult population has serum antibodies, specific for Acanthamoeba antigens. Acanthamoeba is an etiological agent of keratitis and encephalitis diagnosed in human. Acanthamoeba keratitis occurs in healthy persons and may lead to visual impairment and blindness, because corneal infection with this parasite fails to induce cell-mediated immune response due to the absence of resident antigen-presenting cells in the cornea. Systemic immunization with Acanthamoeba antigens induces Th1 cell-mediated immunity and serum IgG antibody, but do not prevent the development of keratitis. Immunization via mucosal surfaces stimulates IgA antibodies in tears and protects against the development of keratitis. Amoebae feed mainly on bacteria, fungi, and algae. By transferring intracellular bacteria, amoeba contributes to the spread of diseases dangerous to humans. Some microorganisms have evolved to become resistant to protist, since they are not internalized or able to survive, grow, and exit free-living protists after internalization. In many cases, the bacteria inside living amoebae survive longer, and multiply better, showing higher virulence. There is a hypothesis, which assumes that Acanthamoeba and symbiontic bacteria survive and multiply better in moist soil, rich in nitrogen compounds, particularly in the vicinity of the root systems of Alnus glutinosa, infected with nitrogen-fixing bacteria Frankia alni. Impact of soil environment created by nitrogen-fixing bacterium Frankia alni on specific relations between protists Acanthamoeba and highly pathogenic bacteria strains in Alnus glutinosa habitats in Poland continue to be established.

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“…Bacteria of order Rickettsiales ( Alphaproteobacteria ) live in an obligate association with a wide range of eukaryotes [1–8], and, for their vast majority, are localized intracellularly, although the case of an extracellular Rickettsiales bacterium was recently documented [9]. Rickettsiales are widely studied for their involvement in medical and veterinary fields.…”

Section: Introductionmentioning

confidence: 99%

Outwitting planarian’s antibacterial defence mechanisms:Rickettsialesbacterial trans-infection fromParamecium multimicronucleatumto planarians

Modeo

Salvetti

Rossi

et al. 2019

Preprint

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AS) 22 23 RUNNING PAGE HEAD: Rickettsiales macronuclear endosymbiont of a ciliate can transiently 24 enter planarian tissues 25 Abstract 38 Most of the microorganisms belonging to genera responsible for vector-borne diseases (VBD) have 39 hematophagous arthropods as vector/reservoir. Recently, many new species of microorganisms 40 phylogenetically related to agents of VBD were found in a variety of aquatic eukaryotic hosts, in 41 particular, numerous new bacterial species related to the genus Rickettsia (Alphaproteobacteria,42 Rickettsiales) were discovered in protist ciliates and other unicellular eukaryotes. Although their 43 pathogenicity for humans and terrestrial animals is not known, these bacteria might act as 44 etiological agents of possible VBD of aquatic organisms, with protist as vectors. In the present 45 study, we characterized a novel strain of the Rickettsia-Like Organism (RLO) endosymbiont 46 "Candidatus (Ca.) Trichorickettsia mobilis" in the macronucleus of the ciliate Paramecium 47 multimicronucleatum through Fluorescence In Situ Hybridization (FISH) and molecular analyses.48 Ultrastructural investigations on the presence of flagella confirmed previous studies on the same 49 bacterial species. The potential trans-infection per os of this bacterium to planarians (Dugesia 50 japonica), a widely used model system able to eliminate a wide range of bacteria pathogenic to 51 humans and other Metazoa, was further verified. Ciliate mass cultures were set up, and trans-52 infection experiments were performed by adding homogenized paramecia to food of antibiotic-53 treated planarians, performed. Treated and non-treated (i.e. control) planarians were investigated at 54 day 1, 3, and 7 after feeding for endosymbiont presence by means of PCR and ultrastructural 55 analyses. Obtained results were fully concordant and suggest that this RLO endosymbiont can be 56 transferred from ciliates to metazoans, being detected up to day 7 in treated planarian enterocytes 57 inside and, possibly, outside phagosomes. 58 59 KEY WORDS Planarians, molecular and ultrastructural investigations, Rickettsiaceae, RLO 60 endosymbiont, trans-infection experiments, vector-borne disease 61 4 62 Introduction63 Bacteria of order Rickettsiales (Alphaproteobacteria) live in an obligate association with a wide range 64 of eukaryotes [1-8], and, for their vast majority, are localized intracellularly, although the case of an 65 extracellular Rickettsiales bacterium was recently documented [9]. Rickettsiales are widely studied 66 for their involvement in medical and veterinary fields. Indeed, many of them (e.g. Rickettsia spp., 67 Anaplasma spp., Ehrlichia spp., and Orientia tsutsugamushi) are vectored by lice, ticks and mites, 68 and cause mild to severe disease [1, 10], such as epidemic typhus, Rocky Mountain spotted fever [11-69 13], anaplasmosis, ehrlichiosis [14, 15], heartwater [16], and scrub typhus [17]. 70 In the last two decades, many new genera and species of Rickettsiales were found as symbionts 71 in a variety of other non-vecto...

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Identification and ultrastructural characterization of Acanthamoeba bacterial endocytobionts belonging to the Alphaproteobacteria class

Cited by 14 publications

References 65 publications

A Systematic Review of Intracellular Microorganisms within Acanthamoeba to Understand Potential Impact for Infection

A Systematic Review of Intracellular Microorganisms within Acanthamoeba to Understand Potential Impact for Infection

Acanthamoeba – pathogen and vector of highly pathogenic bacteria strains to healthy and immunocompromised individuals

Outwitting planarian’s antibacterial defence mechanisms:Rickettsialesbacterial trans-infection fromParamecium multimicronucleatumto planarians

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