Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
6.4
4.5
Journals
Microorganisms
Special Issues
Virulence and Parasitism of Parasitic Protozoa
share announcement

Virulence and Parasitism of Parasitic Protozoa

A special issue of Microorganisms (ISSN 2076-2607). This special issue belongs to the section "Parasitology".

Deadline for manuscript submissions: closed (30 September 2020) | Viewed by 16427

Special Issue Editors

Prof. Dr. Tomoyoshi Nozaki

E-Mail Website
Guest Editor
Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Interests: metabolism; parasitic diseases; molecular parasitology; protozoology; evolutionary parasitology; pathogenesis; NTD drug development; Entamoeba vesicular traffic
Special Issues, Collections and Topics in MDPI journals
Dr. Herbert J. Santos

E-Mail
Guest Editor
Department of Biomedical Chemistry, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Interests: mitosome; mitochondrion related organelles; membrane proteins; Beta barrel proteins; Entamoeba histolytica

Special Issue Information

Dear Colleagues,

Parasitic protozoa comprise a diverse group of organisms that utilize numerous strategies to proliferate in their hosts. Apart from possessing mechanisms that support adhesion and contact to host cells, which may be followed by processes that inflict damage to their hosts while evading host immune action, parasites are also masters of exploiting host machineries and metabolic processes for their survival. In this Special Issue entitled “Virulence and Parasitism of Parasitic Protozoa”, we invite you to contribute original research articles, letters, or reviews related to the parasitic nature of such protozoans, with focus on the elucidation of the mechanisms of virulence, pathogenesis (including their conservation and evolution), and transmission, as well as recent advances in drug and vaccine development.

Prof. Dr. Tomoyoshi Nozaki
Dr. Herbert J. Santos
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Microorganisms is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (6 papers)

Download All Papers
Order results
Result details
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:

Research

Jump to: Review

14 pages, 18609 KiB  
Article
In Vivo and In Vitro Virulence Analysis of Four Genetically Distinct Toxoplasma gondii Lineage III Isolates
by Aleksandra Uzelac, Ivana Klun, Vladimir Ćirković and Olgica Djurković-Djaković
Microorganisms 2020, 8(11), 1702; https://doi.org/10.3390/microorganisms8111702 - 31 Oct 2020
Cited by 7 | Viewed by 2513
Abstract
Toxoplasma gondii archetypes II and III are mildly virulent, yet virulence of variant strains is largely unknown. While lineage II dominates in humans in Europe, lineage III strains are present in various intermediate hosts. In Serbia, lineage III represents 24% of the population [...] Read more.
Toxoplasma gondii archetypes II and III are mildly virulent, yet virulence of variant strains is largely unknown. While lineage II dominates in humans in Europe, lineage III strains are present in various intermediate hosts. In Serbia, lineage III represents 24% of the population structure and occurs most frequently in domestic animals, implying a significant presence in the human food web. In this study, the virulence of four genetically distinct lineage III variants was assessed in vivo and in vitro. In vivo, two strains were shown to be intermediately virulent and two mildly virulent, with cumulative mortalities of 69.4%, 38.8%, 10.7%, and 6.8%, respectively. The strain with the highest mortality has previously been isolated in Europe and may be endemic; the strain with the lowest mortality matches ToxoDB#54, while the remaining two represent novel genotypes. Identical alleles were detected at ROP5, ROP16, ROP18, and GRA15. A set of in vitro analyses revealed proliferation and plaque formation as virulence factors. Higher levels of expression of ENO2 in intermediately virulent strains point to enhanced metabolism as the underlying mechanism. The results suggest that metabolic attenuation, and possibly stage conversion, may be delayed in virulent strains. Full article
(This article belongs to the Special Issue Virulence and Parasitism of Parasitic Protozoa)
►▼ Show Figures

Graphical abstract

18 pages, 2630 KiB  
Article
An Alcohol Dehydrogenase 3 (ADH3) from Entamoeba histolytica Is Involved in the Detoxification of Toxic Aldehydes
by Constantin König, Martin Meyer, Corinna Lender, Sarah Nehls, Tina Wallaschkowski, Tobias Holm, Thorben Matthies, Dirk Lercher, Jenny Matthiesen, Helena Fehling, Thomas Roeder, Sophia Reindl, Maria Rosenthal, Nahla Galal Metwally, Hannelore Lotter and Iris Bruchhaus
Microorganisms 2020, 8(10), 1608; https://doi.org/10.3390/microorganisms8101608 - 19 Oct 2020
Cited by 5 | Viewed by 2415
Abstract
Recently, a putative alcohol dehydrogenase 3, termed EhADH3B of the Entamoeba histolytica isolate HM-1:IMSS was identified, which is expressed at higher levels in non-pathogenic than in pathogenic amoebae and whose overexpression reduces the virulence of pathogenic amoebae. In an in silico analysis performed [...] Read more.
Recently, a putative alcohol dehydrogenase 3, termed EhADH3B of the Entamoeba histolytica isolate HM-1:IMSS was identified, which is expressed at higher levels in non-pathogenic than in pathogenic amoebae and whose overexpression reduces the virulence of pathogenic amoebae. In an in silico analysis performed in this study, we assigned EhADH3B to a four-member ADH3 family, with ehadh3b present as a duplicate (ehadh3ba/ehadh3bb). In long-term laboratory cultures a mutation was identified at position 496 of ehadh3ba, which codes for a stop codon, which was not the case for amoebae isolated from human stool samples. When using transfectants that overexpress or silence ehadh3bb, we found no or little effect on growth, size, erythrophagocytosis, motility, hemolytic or cysteine peptidase activity. Biochemical characterization of the recombinant EhADH3Bb revealed that this protein forms a dimer containing Ni2+ or Zn2+ as a co-factor and that the enzyme converts acetaldehyde and formaldehyde in the presence of NADPH. A catalytic activity based on alcohols as substrates was not detected. Based on the results, we postulate that EhADH3Bb can reduce free acetaldehyde released by hydrolysis from bifunctional acetaldehyde/alcohol dehydrogenase-bound thiohemiacetal and that it is involved in detoxification of toxic aldehydes produced by the host or the gut microbiota. Full article
(This article belongs to the Special Issue Virulence and Parasitism of Parasitic Protozoa)
►▼ Show Figures

Figure 1

12 pages, 1555 KiB  
Article
Differential Pathogenic Gene Expression of E. histolytica in Patients with Different Clinical Forms of Amoebiasis
by Enrique González-Rivas, Miriam Nieves-Ramírez, Ulises Magaña, Patricia Morán, Liliana Rojas-Velázquez, Eric Hernández, Angélica Serrano-Vázquez, Oswaldo Partida, Horacio Pérez-Juárez and Cecilia Ximénez
Microorganisms 2020, 8(10), 1556; https://doi.org/10.3390/microorganisms8101556 - 09 Oct 2020
Cited by 3 | Viewed by 2249
Abstract
The etiological agent of human amoebiasis is the protozoan parasite E. histolytica; the disease is still an endemic infection in some countries and the outcome of infection in the host infection can range from asymptomatic intestinal infection to intestinal or liver invasive [...] Read more.
The etiological agent of human amoebiasis is the protozoan parasite E. histolytica; the disease is still an endemic infection in some countries and the outcome of infection in the host infection can range from asymptomatic intestinal infection to intestinal or liver invasive forms of the disease. The invasive character of this parasite is multifactorial and mainly due to the differential expression of multiple pathogenic genes. The aim of the present work was to measure the differential expression of some genes in different specimens of patients with amoebic liver abscess (ALA) and specimens of genital amoebiasis (AG) by RT-qPCR. Results show that the expression of genes is different in both types of samples. Almost all studied genes were over expressed in both sets of patients; however, superoxide dismutase (Ehsod), serine threonine isoleucine rich protein (Ehstirp), peroxiredoxin (Ehprd) and heat shock protein 70 and 90 (Ehhsp-70, EHhsp-90) were higher in AG biopsies tissue. Furthermore, cysteine proteinases 5 and 2 (Ehcp5, Ehcp2), lectin (Ehgal/galnaclectin) and calreticulin (Ehcrt) genes directly associate with pathogenic mechanisms of E. histolytica had similar over expression in both AG and ALA samples. In summary the results obtained show that trophozoites can regulate the expression of their genes depending on stimuli or environmental conditions, in order to regulate their pathogenicity and ensure their survival in the host. Full article
(This article belongs to the Special Issue Virulence and Parasitism of Parasitic Protozoa)
►▼ Show Figures

Figure 1

17 pages, 5678 KiB  
Article
Import of Entamoeba histolytica Mitosomal ATP Sulfurylase Relies on Internal Targeting Sequences
by Herbert J. Santos, Yoko Chiba, Takashi Makiuchi, Saki Arakawa, Yoshitaka Murakami, Kentaro Tomii, Kenichiro Imai and Tomoyoshi Nozaki
Microorganisms 2020, 8(8), 1229; https://doi.org/10.3390/microorganisms8081229 - 12 Aug 2020
Cited by 2 | Viewed by 2919
Abstract
Mitochondrial matrix proteins synthesized in the cytosol often contain amino (N)-terminal targeting sequences (NTSs), or alternately internal targeting sequences (ITSs), which enable them to be properly translocated to the organelle. Such sequences are also required for proteins targeted to mitochondrion-related organelles (MROs) that [...] Read more.
Mitochondrial matrix proteins synthesized in the cytosol often contain amino (N)-terminal targeting sequences (NTSs), or alternately internal targeting sequences (ITSs), which enable them to be properly translocated to the organelle. Such sequences are also required for proteins targeted to mitochondrion-related organelles (MROs) that are present in a few species of anaerobic eukaryotes. Similar to other MROs, the mitosomes of the human intestinal parasite Entamoeba histolytica are highly degenerate, because a majority of the components involved in various processes occurring in the canonical mitochondria are either missing or modified. As of yet, sulfate activation continues to be the only identified role of the relic mitochondria of Entamoeba. Mitosomes influence the parasitic nature of E. histolytica, as the downstream cytosolic products of sulfate activation have been reported to be essential in proliferation and encystation. Here, we investigated the position of the targeting sequence of one of the mitosomal matrix enzymes involved in the sulfate activation pathway, ATP sulfurylase (AS). We confirmed by immunofluorescence assay and subcellular fractionation that hemagluttinin (HA)-tagged EhAS was targeted to mitosomes. However, its ortholog in the δ-proteobacterium Desulfovibrio vulgaris, expressed as DvAS-HA in amoebic trophozoites, indicated cytosolic localization, suggesting a lack of recognizable mitosome targeting sequence in this protein. By expressing chimeric proteins containing swapped sequences between EhAS and DvAS in amoebic cells, we identified the ITSs responsible for mitosome targeting of EhAS. This observation is similar to other parasitic protozoans that harbor MROs, suggesting a convergent feature among various MROs in favoring ITS for the recognition and translocation of targeted proteins. Full article
(This article belongs to the Special Issue Virulence and Parasitism of Parasitic Protozoa)
►▼ Show Figures

Figure 1

13 pages, 2649 KiB  
Article
Dynamism of PI4-Phosphate during Interactions with Human Erythrocytes in Entamoeba histolytica
by Natsuki Watanabe, Kumiko Nakada-Tsukui, Tomohiko Maehama and Tomoyoshi Nozaki
Microorganisms 2020, 8(7), 1050; https://doi.org/10.3390/microorganisms8071050 - 15 Jul 2020
Cited by 4 | Viewed by 2010
Abstract
Phosphatidylinositol phosphates (PIPs) are involved in many cellular events as important secondary messengers. In Entamoeba histolytica, a human intestinal protozoan parasite, virulence-associated mechanisms such as cell motility, vesicular traffic, trogo- and phagocytosis are regulated by PIPs. It has been well established that [...] Read more.
Phosphatidylinositol phosphates (PIPs) are involved in many cellular events as important secondary messengers. In Entamoeba histolytica, a human intestinal protozoan parasite, virulence-associated mechanisms such as cell motility, vesicular traffic, trogo- and phagocytosis are regulated by PIPs. It has been well established that PI3P, PI4P, and PI(3,4,5)P3 play specific roles during amoebic trogo- and phagocytosis. In the present study, we demonstrated the nuclear localization of PI4P in E. histolytica trophozoites in steady state with immunofluorescence imaging and immunoelectron microscopy, using anti-PI4P antibodies and PI4P biosensors [substrate of the Icm/ Dot type IV secretion system (SidM)]. We further showed that the nuclear PI4P decreased after a co-culture with human erythrocytes or Chinese hamster ovary (CHO) cells. However, concomitant changes in the localization and the amount of PI(4,5)P2, which is the expected major metabolized (phosphorylated) product of PI4P, were not observed. This phenomenon was specifically caused by whole or ghost erythrocytes and CHO cells, but not artificial beads. The amount of PIP2 and PIP, biochemically estimated by [32P]-phosphate metabolic labeling and thin layer chromatography, was decreased upon erythrocyte adherence. Altogether, our data indicate for the first time in eukaryotes that erythrocyte attachment leads to the metabolism of nuclear PIPs, and metabolites other than PI(4,5)P2 may be involved in the regulation of downstream cellular events such as cytoskeleton rearrangement or transcriptional regulation. Full article
(This article belongs to the Special Issue Virulence and Parasitism of Parasitic Protozoa)
►▼ Show Figures

Figure 1

Review

Jump to: Research

24 pages, 8789 KiB  
Review
Crossing the Vacuolar Rubicon: Structural Insights into Effector Protein Trafficking in Apicomplexan Parasites
by Pascal F. Egea
Microorganisms 2020, 8(6), 865; https://doi.org/10.3390/microorganisms8060865 - 08 Jun 2020
Cited by 17 | Viewed by 3686
Abstract
Apicomplexans form a large phylum of parasitic protozoa, including the genera Plasmodium, Toxoplasma, and Cryptosporidium, the causative agents of malaria, toxoplasmosis, and cryptosporidiosis, respectively. They cause diseases not only in humans but also in animals, with dramatic consequences in agriculture. Most apicomplexans are [...] Read more.
Apicomplexans form a large phylum of parasitic protozoa, including the genera Plasmodium, Toxoplasma, and Cryptosporidium, the causative agents of malaria, toxoplasmosis, and cryptosporidiosis, respectively. They cause diseases not only in humans but also in animals, with dramatic consequences in agriculture. Most apicomplexans are vacuole-dwelling and obligate intracellular parasites; as they invade the host cell, they become encased in a parasitophorous vacuole (PV) derived from the host cellular membrane. This creates a parasite–host interface that acts as a protective barrier but also constitutes an obstacle through which the pathogen must import nutrients, eliminate wastes, and eventually break free upon egress. Completion of the parasitic life cycle requires intense remodeling of the infected host cell. Host cell subversion is mediated by a subset of essential effector parasitic proteins and virulence factors actively trafficked across the PV membrane. In the malaria parasite Plasmodium, a unique and highly specialized ATP-driven vacuolar secretion system, the Plasmodium translocon of exported proteins (PTEX), transports effector proteins across the vacuolar membrane. Its core is composed of the three essential proteins EXP2, PTEX150, and HSP101, and is supplemented by the two auxiliary proteins TRX2 and PTEX88. Many but not all secreted malarial effector proteins contain a vacuolar trafficking signal or Plasmodium export element (PEXEL) that requires processing by an endoplasmic reticulum protease, plasmepsin V, for proper export. Because vacuolar parasitic protein export is essential to parasite survival and virulence, this pathway is a promising target for the development of novel antimalarial therapeutics. This review summarizes the current state of structural and mechanistic knowledge on the Plasmodium parasitic vacuolar secretion and effector trafficking pathway, describing its most salient features and discussing the existing differences and commonalities with the vacuolar effector translocation MYR machinery recently described in Toxoplasma and other apicomplexans of significance to medical and veterinary sciences. Full article
(This article belongs to the Special Issue Virulence and Parasitism of Parasitic Protozoa)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-6
Back to TopTop