Characterization of Naegleria fowleri from two human cases: insights into its excretion/secretion products

IntroductionNaegleria fowleri is the etiologic agent of primary acute meningoencephalitis (PAM). Although this amoeba is commonly found in water and soil, reports of infections are rare; problems with diagnosis probably contribute to underestimation. Moreover, information regarding the pathogenicity...

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Main Authors: Natalia Chacón Camacho, María Fernanda Steller Espinoza, Johan Alvarado-Ocampo, Antonio Osuna, Lissette Retana Moreira, Elizabeth Abrahams Sandí
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-05-01
Series:Frontiers in Cellular and Infection Microbiology
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Online Access:https://www.frontiersin.org/articles/10.3389/fcimb.2025.1585448/full
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author Natalia Chacón Camacho
María Fernanda Steller Espinoza
Johan Alvarado-Ocampo
Antonio Osuna
Lissette Retana Moreira
Lissette Retana Moreira
Elizabeth Abrahams Sandí
Elizabeth Abrahams Sandí
author_facet Natalia Chacón Camacho
María Fernanda Steller Espinoza
Johan Alvarado-Ocampo
Antonio Osuna
Lissette Retana Moreira
Lissette Retana Moreira
Elizabeth Abrahams Sandí
Elizabeth Abrahams Sandí
author_sort Natalia Chacón Camacho
collection DOAJ
description IntroductionNaegleria fowleri is the etiologic agent of primary acute meningoencephalitis (PAM). Although this amoeba is commonly found in water and soil, reports of infections are rare; problems with diagnosis probably contribute to underestimation. Moreover, information regarding the pathogenicity of this species is still lacking. Costa Rica reported the first three cases of PAM during 2020; from these, two N. fowleri isolates were recovered. The aim of this study was to characterize and compare these isolates, focusing in excretion/secretion products.MethodsAnalyses of protein profiles by silver staining and protease activity assays were performed to characterize whole protein extracts and conditioned media from isolates. Proteomic analyses of excretion/secretion products, including extracellular vesicles (EVs), were performed, and cytopathic effect and drug susceptibility tests were also compared between isolates.ResultsResults obtained were similar for both isolates. Patterns of multiple bands were observed in each isolate after silver staining. Proteomics analyses revealed a total of 88 and 62 non-redundant proteins as part of the cargo of EVs secreted by trophozoites of N. fowleri Guanacaste and N. fowleri Limón, while conditioned media results revealed 34 and 17 non-redundant proteins, respectively; hydrolase activity and actin filament binding were part of the most represented gene ontology terms in EVs and conditioned media. Regarding drug susceptibility assays, no statistically significant differences were identified. On the other hand, although protease activity resulted very similar with substrate buffer at pH 8.5, only N. fowleri Limón showed activity between 40 and 70 kDa at pH 5.0; in contrast, a more rapid cytopathic effect was observed when incubating Vero cells with N. fowleri Guanacaste.DiscussionComparative analyses of different N. fowleri isolates, supported by their remarkable genomic heterogeneity that could be reflected in different metabolic repertoires, are key to understanding virulence and pathogenicity of this amoeba, and could help to explain whether different isolates differ in the severity or course of PAM.
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spelling doaj-art-16f8dc2b55d64002868e3a94de24eb062025-08-20T02:11:25ZengFrontiers Media S.A.Frontiers in Cellular and Infection Microbiology2235-29882025-05-011510.3389/fcimb.2025.15854481585448Characterization of Naegleria fowleri from two human cases: insights into its excretion/secretion productsNatalia Chacón Camacho0María Fernanda Steller Espinoza1Johan Alvarado-Ocampo2Antonio Osuna3Lissette Retana Moreira4Lissette Retana Moreira5Elizabeth Abrahams Sandí6Elizabeth Abrahams Sandí7Departamento de Parasitología, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa RicaDepartamento de Parasitología, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa RicaCentro de Investigación en Enfermedades Tropicales (CIET), Universidad de Costa Rica, San José, Costa RicaGrupo de Bioquímica y Parasitología Molecular (CTS 183), Departamento de Parasitología, Instituto de Biotecnología, Universidad de Granada, Granada, SpainDepartamento de Parasitología, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa RicaCentro de Investigación en Enfermedades Tropicales (CIET), Universidad de Costa Rica, San José, Costa RicaDepartamento de Parasitología, Facultad de Microbiología, Universidad de Costa Rica, San José, Costa RicaCentro de Investigación en Enfermedades Tropicales (CIET), Universidad de Costa Rica, San José, Costa RicaIntroductionNaegleria fowleri is the etiologic agent of primary acute meningoencephalitis (PAM). Although this amoeba is commonly found in water and soil, reports of infections are rare; problems with diagnosis probably contribute to underestimation. Moreover, information regarding the pathogenicity of this species is still lacking. Costa Rica reported the first three cases of PAM during 2020; from these, two N. fowleri isolates were recovered. The aim of this study was to characterize and compare these isolates, focusing in excretion/secretion products.MethodsAnalyses of protein profiles by silver staining and protease activity assays were performed to characterize whole protein extracts and conditioned media from isolates. Proteomic analyses of excretion/secretion products, including extracellular vesicles (EVs), were performed, and cytopathic effect and drug susceptibility tests were also compared between isolates.ResultsResults obtained were similar for both isolates. Patterns of multiple bands were observed in each isolate after silver staining. Proteomics analyses revealed a total of 88 and 62 non-redundant proteins as part of the cargo of EVs secreted by trophozoites of N. fowleri Guanacaste and N. fowleri Limón, while conditioned media results revealed 34 and 17 non-redundant proteins, respectively; hydrolase activity and actin filament binding were part of the most represented gene ontology terms in EVs and conditioned media. Regarding drug susceptibility assays, no statistically significant differences were identified. On the other hand, although protease activity resulted very similar with substrate buffer at pH 8.5, only N. fowleri Limón showed activity between 40 and 70 kDa at pH 5.0; in contrast, a more rapid cytopathic effect was observed when incubating Vero cells with N. fowleri Guanacaste.DiscussionComparative analyses of different N. fowleri isolates, supported by their remarkable genomic heterogeneity that could be reflected in different metabolic repertoires, are key to understanding virulence and pathogenicity of this amoeba, and could help to explain whether different isolates differ in the severity or course of PAM.https://www.frontiersin.org/articles/10.3389/fcimb.2025.1585448/fullNaegleria fowleritrophozoitesexcretion/secretion productsproteincytotoxicity
spellingShingle Natalia Chacón Camacho
María Fernanda Steller Espinoza
Johan Alvarado-Ocampo
Antonio Osuna
Lissette Retana Moreira
Lissette Retana Moreira
Elizabeth Abrahams Sandí
Elizabeth Abrahams Sandí
Characterization of Naegleria fowleri from two human cases: insights into its excretion/secretion products
Frontiers in Cellular and Infection Microbiology
Naegleria fowleri
trophozoites
excretion/secretion products
protein
cytotoxicity
title Characterization of Naegleria fowleri from two human cases: insights into its excretion/secretion products
title_full Characterization of Naegleria fowleri from two human cases: insights into its excretion/secretion products
title_fullStr Characterization of Naegleria fowleri from two human cases: insights into its excretion/secretion products
title_full_unstemmed Characterization of Naegleria fowleri from two human cases: insights into its excretion/secretion products
title_short Characterization of Naegleria fowleri from two human cases: insights into its excretion/secretion products
title_sort characterization of naegleria fowleri from two human cases insights into its excretion secretion products
topic Naegleria fowleri
trophozoites
excretion/secretion products
protein
cytotoxicity
url https://www.frontiersin.org/articles/10.3389/fcimb.2025.1585448/full
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