In Vitro Differential Phenotypic Characteristics Among Type-II Toxoplasma gondii Strains From Congenital Toxoplasmosis in Humans

After oral ingestion, Toxoplasma gondii crosses the intestinal epithelium, disseminates into the deep tissues, and traverses biological barriers such as the placenta and the blood-brain barrier to reach sites where it causes severe pathology. To examine the cellular basis of these processes, migration of T. gondii was studied in vitro using polarized host cell monolayers and extracellular matrix. Transmigration required active parasite motility and the highly virulent type I strains consistently exhibited a superior migratory capacity than the nonvirulent type II and type III strains. Type I strain parasites also demonstrated a greater capacity for transmigration across mouse intestine ex vivo, and directly penetrated into the lamina propria and vascular endothelium. A subpopulation of virulent type I parasites exhibited a long distance migration (LDM) phenotype in vitro, that was not expressed by nonvirulent type II and type III strains. Cloning of parasites expressing the LDM phenotype resulted in substantial increase of migratory capacity in vitro and in vivo. The potential to up-regulate migratory capacity in T. gondii likely plays an important role in establishing new infections and in dissemination upon reactivation of chronic infections.

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The rural–urban effect on spatial genetic structure of type II Toxoplasma gondii strains involved in human congenital toxoplasmosis, France, 2002–2009

Infection Genetics and Evolution ◽

10.1016/j.meegid.2015.08.025 ◽

2015 ◽

Vol 36 ◽

pp. 511-516 ◽

Cited By ~ 9

Author(s):

Daniel Ajzenberg ◽

Frédéric Collinet ◽

Dominique Aubert ◽

Isabelle Villena ◽

Marie-Laure Dardé ◽

...

Keyword(s):

Genetic Structure ◽

Toxoplasma Gondii ◽

Spatial Genetic Structure ◽

Congenital Toxoplasmosis ◽

Type Ii ◽

Urban Effect

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In vivo and in vitro models show unexpected degrees of virulence among Toxoplasma gondii type II and III isolates from sheep

Veterinary Research ◽

10.1186/s13567-021-00953-7 ◽

2021 ◽

Vol 52 (1) ◽

Author(s):

Mercedes Fernández-Escobar ◽

Rafael Calero-Bernal ◽

Javier Regidor-Cerrillo ◽

Raquel Vallejo ◽

Julio Benavides ◽

...

Keyword(s):

Genetic Diversity ◽

Toxoplasma Gondii ◽

Small Ruminants ◽

Parasite Burden ◽

Target Cells ◽

Post Inoculation ◽

Type Ii ◽

High Genetic Diversity

AbstractToxoplasma gondii is an important zoonotic agent with high genetic diversity, complex epidemiology, and variable clinical outcomes in animals and humans. In veterinary medicine, this apicomplexan parasite is considered one of the main infectious agents responsible for reproductive failure in small ruminants worldwide. The aim of this study was to phenotypically characterize 10 Spanish T. gondii isolates recently obtained from sheep in a normalized mouse model and in an ovine trophoblast cell line (AH-1) as infection target cells. The panel of isolates met selection criteria regarding such parameters as genetic diversity [types II (ToxoDB #1 and #3) and III (#2)], geographical location, and sample of origin (aborted foetal brain tissues or adult sheep myocardium). Evaluations of in vivo mortality, morbidity, parasite burden and histopathology were performed. Important variations between isolates were observed, although all isolates were classified as “nonvirulent” (< 30% cumulative mortality). The isolates TgShSp16 (#3) and TgShSp24 (#2) presented higher degrees of virulence. Significant differences were found in terms of in vitro invasion rates and tachyzoite yield at 72 h post-inoculation (hpi) between TgShSp1 and TgShSp24 isolates, which exhibited the lowest and highest rates, respectively. The study of the CS3, ROP18 and ROP5 loci allelic profiles revealed only type III alleles in ToxoDB #2 isolates and type II alleles in the #1 and #3 isolates included. We concluded that there are relevant intra- and inter-genotype virulence differences in Spanish T. gondii isolates, which could not be inferred by genetic characterization using currently described molecular markers.

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The Role of Type II Fatty Acid Synthesis Enzymes FabZ, ODSCI, and ODSCII in the Pathogenesis of Toxoplasma gondii Infection

Frontiers in Microbiology ◽

10.3389/fmicb.2021.703059 ◽

2021 ◽

Vol 12 ◽

Cited By ~ 1

Author(s):

Xiao-Pei Xu ◽

Hany M. Elsheikha ◽

Wen-Ge Liu ◽

Zhi-Wei Zhang ◽

Li-Xiu Sun ◽

...

Keyword(s):

Fatty Acid ◽

Toxoplasma Gondii ◽

Fatty Acid Biosynthesis ◽

Acyl Carrier Protein ◽

Plaque Assay ◽

Acid Synthesis ◽

Host Cells ◽

Type Ii

Toxoplasma gondii is an obligate intracellular protozoan parasite, which has a worldwide distribution and can infect a large number of warm-blooded animals and humans. T. gondii must colonize and proliferate inside the host cells in order to maintain its own survival by securing essential nutrients for the development of the newly generated tachyzoites. The type II fatty acid biosynthesis pathway (FASII) in the apicoplast is essential for the growth and survival of T. gondii. We investigated whether deletion of genes in the FASII pathway influences the in vitro growth and in vivo virulence of T. gondii. We focused on beta-hydroxyacyl-acyl carrier protein dehydratase (FabZ) and oxidoreductase, short chain dehydrogenase/reductase family proteins ODSCI and ODSCII. We constructed T. gondii strains deficient in FabZ, ODSCI, and ODSCII using CRISPR-Cas9 gene editing technology. The results of immunofluorescence assay, plaque assay, proliferation assay and egress assay showed that in RHΔFabZ strain the apicoplast was partly lost and the growth ability of the parasite in vitro was significantly inhibited, while for RHΔODSCI and RHΔODSCII mutant strains no similar changes were detected. RHΔFabZ exhibited reduced virulence for mice compared with RHΔODSCI and RHΔODSCII, as shown by the improved survival rate. Deletion of FabZ in the PRU strain significantly decreased the brain cyst burden in mice compared with PRUΔODSCI and PRUΔODSCII. Collectively, these findings suggest that FabZ contributes to the growth and virulence of T. gondii, while ODSCI and ODSCII do not contribute to these traits.

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The Toxoplasma gondii-Shuttling Function of Dendritic Cells Is Linked to the Parasite Genotype

Infection and Immunity ◽

10.1128/iai.01289-08 ◽

2009 ◽

Vol 77 (4) ◽

pp. 1679-1688 ◽

Cited By ~ 75

Author(s):

Henrik Lambert ◽

Polya P. Vutova ◽

William C. Adams ◽

Karin Loré ◽

Antonio Barragan

Keyword(s):

Dendritic Cells ◽

Toxoplasma Gondii ◽

Phenotypic Traits ◽

Type I ◽

Type Ii ◽

Parasite Genotype ◽

Type Iii ◽

Parasite Motility

ABSTRACT Following intestinal invasion, the processes leading to systemic dissemination of the obligate intracellular protozoan Toxoplasma gondii remain poorly understood. Recently, tachyzoites representative of type I, II and III T. gondii populations were shown to differ with respect to their ability to transmigrate across cellular barriers. In this process of active parasite motility, type I strains exhibit a migratory capacity superior to those of the type II and type III strains. Data also suggest that tachyzoites rely on migrating dendritic cells (DC) as shuttling leukocytes to disseminate in tissue, e.g., the brain, where cysts develop. In this study, T. gondii tachyzoites sampled from the three populations were allowed to infect primary human blood DC, murine intestinal DC, or in vitro-derived DC and were compared for different phenotypic traits. All three archetypical lineages of T. gondii induced a hypermigratory phenotype in DC shortly after infection in vitro. Type II (and III) strains induced higher migratory frequency and intensity in DC than type I strains did. Additionally, adoptive transfer of infected DC favored the dissemination of type II and type III parasites over that of type I parasites in syngeneic mice. Type II parasites exhibited stronger intracellular association with both CD11c+ DC and other leukocytes in vivo than did type I parasites. Altogether, these findings suggest that infected DC contribute to parasite propagation in a strain type-specific manner and that the parasite genotype (type II) most frequently associated with toxoplasmosis in humans efficiently exploits DC migration for parasite dissemination.

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Infection of mouse neural progenitor cells by Toxoplasma gondii affects in vitro proliferation, differentiation and migration

10.1101/2021.05.31.446482 ◽

2021 ◽

Author(s):

Luiza Bendia Pires ◽

Helene Santos Barbosa ◽

Marcelo Felippe Santiago ◽

Daniel Adesse

Keyword(s):

Cell Proliferation ◽

Toxoplasma Gondii ◽

Progenitor Cells ◽

Neural Progenitor Cells ◽

Congenital Toxoplasmosis ◽

Neural Progenitor ◽

In Vitro Proliferation ◽

Migration Rates ◽

The Impact

Congenital toxoplasmosis constitutes a major cause of pre- and post-natal complications. Fetal infection with Toxoplasma gondii influences development and can lead to microcephaly, encephalitis, and neurological abnormalities. Few studies have attempted to explain the impact of T. gondii infection on the physiology of mature nerve cells, and no systematic study concerning the effect of infection of neural progenitor cells by T. gondii in the biology of these progenitors is available. We infected cortical intermediate progenitor cell cultivated as neurospheres obtained from E16.5 Swiss Webster mice with T. gondii (Me49 strain) tachyzoites to mimic the developing mouse cerebral cortex in vitro. Infection decreased cell proliferation as detected by Ki67 staining at 48 and 72 hours post infection (hpi) in floating neurospheres, resulting in reduced cellularity at 96 hpi. Neurogenic and gliogenic potential, assessed in plated neurospheres, was shown to be impaired in infected cultures, as indicated by neurofilament heavy chain (NF-200) and GFAP staining, respectively. To further investigate the impact of infection on neuronal differentiation, Neuro2a neuroblasts were infected and after 24 hpi, neurogenic differentiation was induced with serum withdrawal. We confirmed that infection induces a decrease in neuroblast-neuron differentiation rates in cells stained for NF-200, with reduced neuritogenesis. Migration rates were analyzed in plated neurospheres. At 120 h after plating, infected cultures exhibited decreased overall migration rates and altered the radial migration of nestin-, GFAP- and NF-200-positive cells. These findings indicate that T. gondii infection of neural progenitor cells may lead to reduced neuro/gliogenesis due to an imbalance in cell proliferation alongside an altered migratory profile. If translated to the in vivo situation, these data could explain, in part, the cortical malformations observed in congenitally infected individuals.

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Toxoplasma gondii: the changing paradigm of congenital toxoplasmosis

Parasitology ◽

10.1017/s0031182011001478 ◽

2011 ◽

Vol 138 (14) ◽

pp. 1829-1831 ◽

Cited By ~ 47

Author(s):

D. S. LINDSAY ◽

J. P. DUBEY

Keyword(s):

United States ◽

Toxoplasma Gondii ◽

Population Biology ◽

Congenital Toxoplasmosis ◽

The United States ◽

Women Physicians ◽

Type I ◽

Type Ii ◽

The Past ◽

New Information

SUMMARYResearchers have learned much concerning the population biology ofToxoplasma gondiiover the past 2 decades. It is now apparent that many atypical genotypes exist besides the typical 3 genotypes (type I, type II and type III) first described from samples from Europe and the United States. These genotypes can differ in pathogenicity and transmissibility from the typical genotypes that have been used in the majority of scientific research over the past 70 years. These differences impact much of what we used to believe as facts about congenital toxoplasmosis (CT) and will be important in developing new recommendations for prevention of CT and the monitoring of women at risk for developing CT. The present review highlights new information onT. gondiigenotypes and how this information will change the way we convey information about CT to pregnant women, physicians and students.

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