scholarly journals Insight Into Inflammasome Signaling: Implications for Toxoplasma gondii Infection

2020 ◽  
Vol 11 ◽  
Author(s):  
Yang Wang ◽  
Jinjin Zhu ◽  
Yuanyuan Cao ◽  
Jilong Shen ◽  
Li Yu
Keyword(s):  
Toxoplasma Gondii ◽  
Protein Complexes ◽  
Innate Immune ◽  
Leucine Rich Repeat ◽  
Proteolytic Activation ◽  
Obligate Intracellular ◽  
Obligate Intracellular Parasite ◽  
Multimeric Protein ◽  
Toxoplasma Gondii Infection ◽  
Insight Into

Inflammasomes are multimeric protein complexes regulating the innate immune response to invading pathogens or stress stimuli. Recent studies have reported that nucleotide-binding leucine-rich repeat-containing (NLRs) proteins and DNA sensor absent in melanoma 2 (AIM2) serve as inflammasome sentinels, whose stimulation leads to the proteolytic activation of caspase-1, proinflammatory cytokine secretion, and pyroptotic cell death. Toxoplasma gondii, an obligate intracellular parasite of phylum Apicomplexans, is reportedly involved in NLRP1, NLRP3 and AIM2 inflammasomes activation; however, mechanistic evidence regarding the activation of these complexes is preliminary. This review describes the current understanding of inflammasome signaling in rodent and human models of T. gondii infection.

Documented Outbreaks of Toxoplasmosis: Transmission of Toxoplasma gondii to Humans

1993 ◽  
Vol 56 (7) ◽  
pp. 630-639 ◽  
Author(s):  
JAMES L. SMITH
Keyword(s):  
Toxoplasma Gondii ◽  
Food Supply ◽  
Control Mechanisms ◽  
Intracellular Parasite ◽  
Obligate Intracellular ◽  
Obligate Intracellular Parasite ◽  
Toxoplasma Gondii Infection ◽  
The U.S

Toxoplasmosis, a disease of mammals and birds, is caused by the obligate intracellular parasite, Toxoplasma gondii. Infection by the parasite is common (35–50% of the U.S. population are infected), but the disease, toxoplasmosis, is relatively rare and outbreaks of the disease are seldom seen. Documented outbreaks of toxoplasmosis are discussed to illustrate conditions that lead to outbreaks and how T. gondii is transmitted to humans. Recommendations are made of means to prevent introduction of the parasite into the environment and food supply as well as control mechanisms to prevent infection in humans and animals.

Invasion of Toxoplasma gondii occurs by active penetration of the host cell

1995 ◽  
Vol 108 (6) ◽  
pp. 2457-2464 ◽  
Author(s):  
J.H. Morisaki ◽  
J.E. Heuser ◽  
L.D. Sibley
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Tyrosine Phosphorylation ◽  
Host Cells ◽  
The Novel ◽  
Host Proteins ◽  
Host Cell Membrane ◽  
Membrane Ruffling ◽  
Obligate Intracellular ◽  
Obligate Intracellular Parasite

Toxoplasma gondii is an obligate intracellular parasite that infects a wide variety of vertebrate cells including macrophages. We have used a combination of video microscopy and fluorescence localization to examine the entry of Toxoplasma into macrophages and nonphagocytic host cells. Toxoplasma actively invaded host cells without inducing host cell membrane ruffling, actin microfilament reorganization, or tyrosine phosphorylation of host proteins. Invasion occurred rapidly and within 25–40 seconds the parasite penetrated into a tight-fitting vacuole formed by invagination of the plasma membrane. In contrast, during phagocytosis of Toxoplasma, extensive membrane ruffling captured the parasite in a loose-fitting phagosome that formed over a period of 2–4 minutes. Phagocytosis involved both reorganization of the host cytoskeleton and tyrosine phosphorylation of host proteins. In some cases, parasites that were first internalized by phagocytosis, were able to escape from the phagosome by a process analogous to invasion. These studies reveal that active penetration of the host cell by Toxoplasma is fundamentally different from phagocytosis or induced endocytic uptake. The novel ability to penetrate the host cell likely contributes to the capability of Toxoplasma-containing vacuoles to avoid endocytic processing.

scholarly journals A selector of transcription initiation in the protozoan parasite Toxoplasma gondii.

1995 ◽  
Vol 15 (1) ◽  
pp. 87-93 ◽  
Author(s):  
D Soldati ◽  
J C Boothroyd
Keyword(s):  
Toxoplasma Gondii ◽  
Gene Transcription ◽  
Transcription Initiation ◽  
Protozoan Parasite ◽  
Intracellular Parasite ◽  
Transcription Start ◽  
Transcription Start Sites ◽  
Obligate Intracellular ◽  
Obligate Intracellular Parasite ◽  
Sag1 Gene

The recent development of an efficient transfection system for the apicomplexan Toxoplasma gondii allows a comprehensive dissection of the elements involved in gene transcription in this obligate intracellular parasite. We demonstrate here that for the SAG1 gene, a stretch of six repeated sequences in the region 35 to 190 bp upstream of the first of two transcription start sites is essential for efficient and accurate transcription initiation. This repeat element shows characteristics of a selector in determining the position of the transcription start sites.

scholarly journals Investigation of Toxoplasma gondii Infection in Aborted Fetuses of Sheep Using PCR: A Study in North Khorasan Province, Iran

2020 ◽  
Vol 2020 ◽  
pp. 1-5
Author(s):  
Mitra Salehi ◽  
Hosein Nezami ◽  
Hamid Reza Niazkar
Keyword(s):  
Toxoplasma Gondii ◽  
Gestational Age ◽  
Protozoan Parasite ◽  
Abortion Rate ◽  
Obligate Intracellular ◽  
Significant Difference ◽  
Pcr Method ◽  
Toxoplasma Gondii Infection ◽  
Intracellular Protozoan Parasite

Toxoplasma gondii is a zoonotic obligate intracellular protozoan parasite that infects warm-blooded animals as well as humans worldwide. The purpose of this study was to delineate the prevalence of Toxoplasma infection in aborted fetuses of sheep in North Khorasan province, Iran. Three hundred and ninety-nine samples of the liver (133 samples), placenta (133 samples), and brain (133 samples) from 133 aborted fetuses of sheep were collected from 2015 to 2017. The ages of aborted fetuses were higher than 120 days’ gestational age in this study. According to the samples, sixteen out of 133 aborted fetuses of sheep were infected with T. gondii. Toxoplasma DNA was found in the placenta (68.75%) and liver (31.25%) samples of infected fetuses using the PCR method. The highest and lowest rates of Toxoplasma infection were observed during 2016 and 2017, respectively. Shirvan and Faruj provinces were recognized as the two most infected districts among others. There was a significant difference between the year and abortion rate in sheep due to infection by the Toxoplasma parasite (P<0.05). Furthermore, no significant difference between the prevalence of T. gondii infection and aborted fetuses was seen (P>0.05) in different areas. According to the present study, T. gondii infection can be one of the causes of fetus abortion of sheep in North Khorasan province, Iran.

The occurrence of Toxoplasma gondii on raw leafy vegetables in Gaza - Palestine

2020 ◽  
Author(s):  
Zuhair Dardona ◽  
Samia BOUSSAA ◽  
Adnan Al-Hindi ◽  
Ali aboumezzough ◽  
Mohamed Hafidi
Keyword(s):  
Toxoplasma Gondii ◽  
Solution Method ◽  
Leafy Vegetables ◽  
Foodborne Diseases ◽  
Intracellular Parasite ◽  
Obligate Intracellular ◽  
Obligate Intracellular Parasite ◽  
Flotation Technique ◽  
Pcr Method ◽  
The Relationship

Toxoplasma gondii  a ubiquitous obligate intracellular parasite that can infect all warm-blooded animals, is one of the main pathogens causing foodborne diseases worldwide. In Gaza – Palestine, the leafy vegetables are frequently eaten raw.  The present study was carried out to investigate the occurrence of T. gondii oocyst in local leafy vegetables. For this purpose, fifty samples of each kind of six different leafy plants sold in markets, supermarkets, and retail sellers were randomly collected during the period from March to August 2019. , the three hundred samples were collected from six different species of leafy vegetables. The samples were examined microscopy through using a light microscope and after performing the flotation technique of Sheather's solution to easily detect the oocysts, the suspected samples were confirmed by using PCR technique. Upon analyzing the samples and using the PCR method, only 19 out of the 300 samples (6.33 %) were found to be contaminated, whereas by using Sheather's solution method, 35 out of the 300 samples (11.66%) were contaminated. Among the six various plants and according to the PCR method, mint held the highest rate of contamination (10.00 %), followed by both watercress and dill with a similar percentage (8.00%), parsley (6.00%), thyme (4.00%),  and finally, lettuce carrying the lowest rate (2.00%). Even though the sequence among those contaminated plants was found similar in the PCR and the Sheather's solution, the rates were different. With this method, mint stood at (18.00%), watercress (14.00%), dill (13.00%), parsley (10.00%), thyme (10.00%) and lettuce (6.00%). Moreover, the present study has reported that the relationship between the period of collection and T. gondii contamination is statistically significant. Whereby, the highest rate of contamination recorded was in July, followed by June, then August. Based on the findings of the present study, leafy vegetables are quite vulnerable to T. gondii contamination.

scholarly journals Making Home Sweet and Sturdy: Toxoplasma gondii ppGalNAc-Ts Glycosylate in Hierarchical Order and Confer Cyst Wall Rigidity

mBio ◽  
2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Tadakimi Tomita ◽  
Tatsuki Sugi ◽  
Rama Yakubu ◽  
Vincent Tu ◽  
Yanfen Ma ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Cyst Wall ◽  
Dependent Manner ◽  
Intracellular Parasite ◽  
Congenital Disease ◽  
Brain Cyst ◽  
Obligate Intracellular ◽  
Obligate Intracellular Parasite ◽  
Structural Rigidity ◽  
The Brain

ABSTRACT The protozoan intracellular parasite Toxoplasma gondii forms latent cysts in the central nervous system (CNS) and persists for the lifetime of the host. This cyst is cloaked with a glycosylated structure called the cyst wall. Previously, we demonstrated that a mucin-like glycoprotein, CST1, localizes to the cyst wall and confers structural rigidity on brain cysts in a mucin-like domain-dependent manner. The mucin-like domain of CST1 is composed of 20 units of threonine-rich tandem repeats that are O-GalNAc glycosylated. A family of enzymes termed polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts) initiates O-GalNAc glycosylation. To identify which isoforms of ppGalNAc-Ts are responsible for the glycosylation of the CST1 mucin-like domain and to evaluate the function of each ppGalNAc-T in the overall glycosylation of the cyst wall, all five ppGalNAc-T isoforms were deleted individually from the T. gondii genome. The ppGalNAc-T2 and -T3 deletion mutants produced various glycosylation defects on the cyst wall, implying that many cyst wall glycoproteins are glycosylated by T2 and T3. Both T2 and T3 glycosylate the CST1 mucin-like domain, and this glycosylation is necessary for CST1 to confer structural rigidity on the cyst wall. We established that T2 is required for the initial glycosylation of the mucin-like domain and that T3 is responsible for the sequential glycosylation on neighboring acceptor sites, demonstrating hierarchical glycosylation by two distinct initiating and filling-in ppGalNAc-Ts in an intact organism. IMPORTANCE Toxoplasma gondii is an obligate intracellular parasite that infects a third of the world’s population. It can cause severe congenital disease and devastating encephalitis in immunocompromised individuals. We identified two glycosyltransferases, ppGalNAc-T2 and -T3, which are responsible for glycosylating cyst wall proteins in a hierarchical fashion. This glycosylation confers structural rigidity on the brain cyst. Our studies provide new insights into the mechanisms of O-GalNAc glycosylation in T. gondii. IMPORTANCE Toxoplasma gondii is an obligate intracellular parasite that infects a third of the world’s population. It can cause severe congenital disease and devastating encephalitis in immunocompromised individuals. We identified two glycosyltransferases, ppGalNAc-T2 and -T3, which are responsible for glycosylating cyst wall proteins in a hierarchical fashion. This glycosylation confers structural rigidity on the brain cyst. Our studies provide new insights into the mechanisms of O-GalNAc glycosylation in T. gondii.

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