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Various brain-eating amoebae: the protozoa, the pathogenesis, and the disease. Front Med 2021; 15:842-866. [PMID: 34825341 DOI: 10.1007/s11684-021-0865-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 04/25/2021] [Indexed: 10/19/2022]
Abstract
Among various genera of free-living amoebae prevalent in nature, some members are identified as causative agents of human encephalitis, in which Naegleria fowleri followed by Acanthamoeba spp. and Balamuthia mandrillaris have been successively discovered. As the three dominant genera responsible for infections, Acanthamoeba and Balamuthia work as opportunistic pathogens of granulomatous amoebic encephalitis in immunocompetent and immunocompromised individuals, whereas Naegleria induces primary amoebic meningoencephalitis mostly in healthy children and young adults as a more violent and deadly disease. Due to the lack of typical symptoms and laboratory findings, all these amoebic encephalitic diseases are difficult to diagnose. Considering that subsequent therapies are also affected, all these brain infections cause significant mortality worldwide, with more than 90% of the cases being fatal. Along with global warming and population explosion, expanding areas of human and amoebae activity in some regions lead to increased contact, resulting in more serious infections and drawing increased public attention. In this review, we summarize the present information of these pathogenic free-living amoebae, including their phylogeny, classification, biology, and ecology. The mechanisms of pathogenesis, immunology, pathophysiology, clinical manifestations, epidemiology, diagnosis, and therapies are also discussed.
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Kang AY, Park AY, Shin HJ, Khan NA, Maciver SK, Jung SY. Production of a monoclonal antibody against a mannose-binding protein of Acanthamoeba culbertsoni and its localization. Exp Parasitol 2018; 192:19-24. [PMID: 30031120 DOI: 10.1016/j.exppara.2018.07.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 06/21/2018] [Accepted: 07/17/2018] [Indexed: 10/28/2022]
Abstract
Amoebae from the genus Acanthamoeba are facultative pathogens of humans and other animals. In humans they most frequently infect the eye causing a sight threatening infection known as Acanthamoeba keratitis (AK), and also cause an often fatal encephalitis (GAE). A mannose-binding protein (MBP) has been identified as being important for Acanthamoeba infection especially in AK. This lectin has previously been characterized from Acanthamoeba castellanii as consisting of multiple 130 kDa subunits. MBP expression correlates with pathogenic potential and is expressed in a number of Acanthamoeba species. Here we report the purification of a similar lectin from Acanthamoeba culbertsoni and the production of a monoclonal antibody to it. The A. culbertsoni MBP was isolated by affinity chromatography using α-D-mannose agarose and has an apparent molecular weight of 83 kDa. The monoclonal antibody is an IgM that is useful in both western blots and immunofluorescence. We expect that this antibody will be useful in the study of the pathology of A. culbertsoni and in its identification in clinical samples.
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Affiliation(s)
- A-Young Kang
- Department of Biomedical Laboratory Science, Molecular Diagnostics Research Institute, Namseoul University, Cheonan 31020, Republic of Korea
| | - A-Young Park
- Department of Biomedical Laboratory Science, Molecular Diagnostics Research Institute, Namseoul University, Cheonan 31020, Republic of Korea
| | - Ho-Joon Shin
- Department of Microbiology, and Molecular Science & Technology, Ajou University School of Medicine, Suwon, 443-721, Republic of Korea
| | - Naveed Ahmed Khan
- Department of Biological Sciences, School of Science and Technology, Sunway University, Malaysia
| | - Sutherland K Maciver
- Centre for Discovery Brain Sciences, Biomedical Sciences, Edinburgh Medical School, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, Scotland, UK.
| | - Suk-Yul Jung
- Department of Biomedical Laboratory Science, Molecular Diagnostics Research Institute, Namseoul University, Cheonan 31020, Republic of Korea.
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Abstract
Acanthamoeba and Naegleria are widely distributed in fresh water, soil and dust throughout the world, and cause meningoencephalitis or keratoconjunctivitis in humans and other mammals. Korean isolates, namely, Naegleria sp. YM-1 and Acanthamoeba sp. YM-2, YM-3, YM-4, YM-5, YM-6 and YM-7, were collected from sewage, water puddles, a storage reservoir, the gills of a fresh water fish, and by corneal washing. These isolates were categorized into three groups based on the mortalities of infected mice namely, highly virulent (YM-4), moderately virulent (YM-2, YM-5 and YM-7) and nonpathogenic (YM-3). In addition, a new species of Acanthamoeba was isolated from a freshwater fish in Korea and tentatively named Korean isolate YM-4. The morphologic characters of its cysts were similar to those of A. culbertsoni and A. royreba, which were previously designated as Acanthamoeba group III. Based on experimentally infected mouse mortality, Acanthamoeba YM-4 was highly virulent. The isoenzymes profile of Acanthamoeba YM-4 was similar to that of A. royreba. Moreover, an anti-Acanthamoeba YM-4 monoclonal antibody reacted only with Acanthamoeba YM-4, and not with A. culbertsoni. Random amplified polymorphic DNA marker analysis and RFLP analysis of mitochondrial DNA and of a 18S small subunit ribosomal RNA, placed Acanthamoeba YM-4 in a separate cluster based on phylogenic distances. Thus Acanthamoeba YM-4 was identified as a new species, and assigned Acanthamoeba sohi. Up to the year 2002 in Korea, two clinical cases were found to be infected with Acanthamoeba spp. These patients died of meningoencephalitis. In addition, one case of Acanthamoeba pneumonia with an immunodeficient status was reported and Acanthamoeba was detected in several cases of chronic relapsing corneal ulcer, chronic conjunctivitis, and keratitis.
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Affiliation(s)
- Ho-Joon Shin
- Department of Microbiology, Ajou University School of Medicine, Suwon 442-749, Repubic of Korea
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Jeong SR, Cho MS, Park S, Kim KH, Song KJ, Im KI, Shin HJ. Cloning and characterization of an immunoreactive gene encoding a calcium-binding protein from Naegleria fowleri. Mol Biochem Parasitol 2004; 137:169-73. [PMID: 15279963 DOI: 10.1016/j.molbiopara.2004.04.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2003] [Revised: 12/22/2003] [Accepted: 04/08/2004] [Indexed: 10/26/2022]
Affiliation(s)
- Seok-Ryoul Jeong
- Department of Microbiology, Ajou University School of Medicine, Suwon 442-749, Republic of Korea
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Cho MS, Jung SY, Park S, Kim KH, Kim HI, Sohn S, Kim HJ, Im KI, Shin HJ. Immunological characterizations of a cloned 13.1-kilodalton protein from pathogenic Naegleria fowleri. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2003; 10:954-9. [PMID: 12965933 PMCID: PMC193893 DOI: 10.1128/cdli.10.5.954-959.2003] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2003] [Revised: 05/05/2003] [Accepted: 06/05/2003] [Indexed: 11/20/2022]
Abstract
We previously cloned an antigenic gene (named nfa1) from a cDNA library of Naegleria fowleri by immunoscreening. The nfa1 gene had a coding nucleotide sequence consisting of 357 bases and produced a recombinant 13.1-kDa protein (Nfa1). In this study, to get more information regarding the recombinant Nfa1 protein (rNfa1), we produced an anti-Nfa1 polyclonal antibody from mice immunized with rNfa1 and used a peroxidase staining method to carry out immunocytochemistry experiments. In addition, we observed the effect of the presence of an anti-Nfa1 antibody on the in vitro cytotoxicity of N. fowleri against Chinese hamster ovary (CHO) cells. Trophozoites of N. fowleri in cultivation reacted strongly with a peroxidase-labeled anti-Nfa1 antibody. In inflammatory and necrotic regions of brain tissue infected with N. fowleri, labeled trophozoites that were stained brown were also observed. When examined using a transmission electron microscope, the Nfa1 protein showed pseudopodium-specific immunolocalization on a trophozoite of N. fowleri. When examined using a light microscope, CHO cells grown in cocultures with N. fowleri trophozoites (group I) for 48 h showed morphologically severe destruction but CHO cells grown in cocultures with N. fowleri trophozoites and an anti-Nfa1 polyclonal antibody (group II) showed less destruction. The results of a lactate dehydrogenase release assay showed that group I CHO cells exhibited 81% cytotoxicity and group II CHO cells exhibited 13.8% cytotoxicity.
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Affiliation(s)
- Myoung-Soo Cho
- Department of Microbiology, School of Medicine, Ajou University, Suwon 442-749, Korea
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Shin HJ, Cho MS, Jung SU, Kim HI, Park S, Kim HJ, Im KI. Molecular cloning and characterization of a gene encoding a 13.1 kDa antigenic protein of Naegleria fowleri. J Eukaryot Microbiol 2001; 48:713-7. [PMID: 11831780 DOI: 10.1111/j.1550-7408.2001.tb00211.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An antigen-related gene was cloned from a cDNA expression library of Naegleria fowleri by immunoscreening with sera obtained from mice that were either immunized with an amoebic lysate or infected with trophozoites. The coding nucleotide sequence of the cloned gene consisted of 357 bases that were translated into 119 amino acids. This gene was designated as nfa1. The predicted amino acid sequence of Nfa1 protein has two potential glycosylation and three potential phosphorylation sites, and its predicted secondary structure consists of four helices and three corners. The deduced amino acid sequence of Nfa1 protein shares 43% identity with the myohemerythrin (myoHr) protein from a marine annelid, Nereis diversicolor, including 100% identity in conserved regions and iron-binding residues. A phylogenetic tree constructed from amino acid sequences placed the N. fowleri Nfa1 protein outside of a cluster of myoHr proteins from eight invertebrates. A purified recombinant protein that migrated as a 13.1 kDa species in SDS-PAGE was produced. This recombinant protein exhibited a strong immunoreactivity with infected, immune, and anti-Nfal sera. In addition, an anti-Nfa1 serum reacted with an amoeba lysate in immunoblotting analysis. The present nfal gene encoding the myoHr-like protein is the first myoHr gene cloned from protozoa, and the Nfal antigen may be useful in diagnostic studies
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Affiliation(s)
- H J Shin
- Department of Microbiology, Ajou University School of Medicine, Suwon, Korea.
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Shin HJ, Kim CH, Im KI. [Immunological approach for classification of free-living amoeba in Korea]. KISAENGCH'UNGHAK CHAPCHI. THE KOREAN JOURNAL OF PARASITOLOGY 1992; 30:289-98. [PMID: 1297420 DOI: 10.3347/kjp.1992.30.4.289] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Acanthamoeba spp., free-living amoebae inhabited in moist soil, pond, freshwater, sewage, atmosphere and swimming pool, may be causative protozoa of the fatal primary amoebic meningoencephalitis in experimental animals and humans. In this study, Acanthamoeba spp., including Acanthamoeba sp. YM-4 (isolated strain from Korea) had been compared by the two-dimensional electrophoresis and hybridoma technique as well as the difference of morphological characteristics. Trophozoite of Acanthamoeba sp. YM-4 is usually uninucleate and show the hyaline filamentous projections (acanthopoda). No flagellate stage observed. Cysts have two walls, the outer wall is nearly circular, but inner wall is oval or some irregular. As results of SDS-PAGE for lysate of Acanthamoeba sp. YM-4, 16 major protein fractions are similar to those of A. culbertsoni, but different to A. royreba and A. polyphaga. Findings of two-dimensional electrophoretic patterns of Acanthamoeba sp. YM-4 are almost same to those of A. culbertsoni, The isotype of monoclonal antibodies produced from McAY 6, McAY 7, McAY 8, McAY 13 and McAY 16 clones were IgG1, and McAY 10 and McAY 11 clones were IgM. As results of the cross-reactivity among various amoebae using ELISA with monoclonal antibodies, McAY 7 monoclonal antibody (molecular weight 43 kDa by EITB) was only reacted with Acanthamoeba sp. YM-4, but McAY 6 and McAY 10 monoclonal antibodies were reacted to A. culbertsoni as well as Acanthamoeba sp. YM-4.
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Affiliation(s)
- H J Shin
- Department of Biology, College of Natural Science, Chungnam National University, Taejon, Korea
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Soh EY, Shin HJ, Im K. [The protective effects of monoclonal antibodies in mice from Naegleria fowleri infection]. KISAENGCH'UNGHAK CHAPCHI. THE KOREAN JOURNAL OF PARASITOLOGY 1992; 30:113-23. [PMID: 1627499 DOI: 10.3347/kjp.1992.30.2.113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Protective effects of monoclonal antibodies against N. fowleri were comparatively studied. BALB/c mice were treated with two types of monoclonal antibodies, Nf 2 and Nf 154, before and after the infection with N. fowleri. The mortality and mean survival times were then compared. Also, direct effect of the monoclonal antibodies on the N. fowleri trophozoites in vitro were observed. In vitro protective effects of the monoclonal antibodies were also studied in cells infected with N. fowleri. The observed results are summarized as follows: 1. Among mice pretreated twice before the infection with monoclonal antibody Nf 2(McAb Nf 2), only 15.8% were killed, and the mean survival time was 17.7 days. This was not much different from the mice pretreated once, as the mortality and mean survival time were 16.7% and 17 days. Those effects were compatible with monoclonal antibody Nf 154(McAb Nf 154). The above findings contrast with the mortality and mean survival time of the control mice, which were 22.7% and 14.6 days respectively. 2. Mice which received twice the McAb Nf 2 following N. fowleri infection incurred a 19.4% mortality rate with 13.6 days survival time; 17.9% and 15.8 days with on time administration, in contrast to the 25% and 14.6 days in the control group. 3. Marked agglutination effect of McAb Nf 2 or McAb Nf 154 were observed on N. fowleri trophozoites. 4. When N. fowleri trophozoites were treated with McAb Nf 2 or McAb Nf 154 combined with comments, the proliferation rate was more significantly suppressed than in that the control. 5. N. fowleri trophozoites treated with McAb Nf 2 or McAb Nf 154 showed an increased number of swollen mitochondria, disfigured cisternae, lipid droplets, and osmiophilic granules in the cytoplasm. 6. A remarkable protective effect of monoclonal antibodies was noticed in CHO cells infected with N. fowleri. More than 90.6% of the infected CHO cells survived, contrasted with 27% of untreated cells. The overall results in this study suggest that N. fowleri treated with monoclonal antibodies against N. fowleri reduce the mortality and prolong the survival time of the mice when the antibodies are administered before the infection. The protective effect of the monoclonal antibodies is surmised being caused by agglutination of the trophozoites.
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Affiliation(s)
- E Y Soh
- Department of General Surgery, College of Medicine, Aju University, Suwon, Korea
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