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Parasites & Vectors May 2015Toxoplasmosis, caused by the obligate intracellular protozoan Toxoplasma gondii, is an important zoonosis with medical and veterinary importance worldwide. The disease... (Review)
Review
Toxoplasmosis, caused by the obligate intracellular protozoan Toxoplasma gondii, is an important zoonosis with medical and veterinary importance worldwide. The disease is mainly contracted by ingesting undercooked or raw meat containing viable tissue cysts, or by ingesting food or water contaminated with oocysts. The diagnosis and genetic characterization of T. gondii infection is crucial for the surveillance, prevention and control of toxoplasmosis. Traditional approaches for the diagnosis of toxoplasmosis include etiological, immunological and imaging techniques. Diagnosis of toxoplasmosis has been improved by the emergence of molecular technologies to amplify parasite nucleic acids. Among these, polymerase chain reaction (PCR)-based molecular techniques have been useful for the genetic characterization of T. gondii. Serotyping methods based on polymorphic polypeptides have the potential to become the choice for typing T. gondii in humans and animals. In this review, we summarize conventional non-DNA-based diagnostic methods, and the DNA-based molecular techniques for the diagnosis and genetic characterization of T. gondii. These techniques have provided foundations for further development of more effective and accurate detection of T. gondii infection. These advances will contribute to an improved understanding of the epidemiology, prevention and control of toxoplasmosis.
Topics: Animals; Diagnostic Tests, Routine; Humans; Toxoplasma; Toxoplasmosis
PubMed: 26017718
DOI: 10.1186/s13071-015-0902-6 -
Current Biology : CB Jul 2018Putting cat lovers on notice: Toxoplasma gondii is here to control your brain…or is it? Kochanowsky and Koshy shine the spotlight on this notorious pathogen.
Putting cat lovers on notice: Toxoplasma gondii is here to control your brain…or is it? Kochanowsky and Koshy shine the spotlight on this notorious pathogen.
Topics: Animals; Host-Parasite Interactions; Humans; Life History Traits; Toxoplasma; Toxoplasmosis; Toxoplasmosis, Animal
PubMed: 30040931
DOI: 10.1016/j.cub.2018.05.035 -
Microbiological Research Oct 2019T. gondii is a major opportunistic pathogen chronically infecting nearly one third of the world's population. Due to the high infection and mortality rates in... (Review)
Review
T. gondii is a major opportunistic pathogen chronically infecting nearly one third of the world's population. Due to the high infection and mortality rates in immunocompromised patients and newborns, the extent or magnitude of T. gondii pathogenesis is determined mainly by host-pathogen interactions. T. gondii utilizes specialized secretory proteins to modify host cellular factors and facilitate invasion and replication. This review provides update on the recent progress in this field of research with particular emphasis on the T. gondii secretory proteins and their role in invasion and pathogenesis.
Topics: Animals; Host-Parasite Interactions; Humans; Life Cycle Stages; Protein Transport; Protozoan Proteins; Toxoplasma; Toxoplasmosis
PubMed: 31421715
DOI: 10.1016/j.micres.2019.06.003 -
Frontiers in Cellular and Infection... 2019is an intracellular protozoan parasite of global importance that can remarkably infect, survive, and replicate in nearly all mammalian cells. Notably, 110 years after... (Review)
Review
is an intracellular protozoan parasite of global importance that can remarkably infect, survive, and replicate in nearly all mammalian cells. Notably, 110 years after its discovery, Toxoplasmosis is still a neglected parasitic infection. Although most human infections with are mild or asymptomatic, infection can result in life-threatening disease in immunocompromised individuals and in the developing fetus due to congenital infection, underscoring the role of the host immune system in controlling the parasite. Recent evidence indicates that elicits a robust innate immune response during infection. Interestingly, however, has evolved strategies to successfully bypass or manipulate the immune system and establish a life-long infection in infected hosts. In particular, manipulates host immunity through the control of host gene transcription and dysregulation of signaling pathways that result in modulation of cell adhesion and migration, secretion of immunoregulatory cytokines, production of microbicidal molecules, and apoptosis. Many of these host-pathogen interactions are governed by parasite effector proteins secreted from the apical secretory organelles, including the rhoptries and dense granules. Here, we review recent findings on mechanisms by which evades host innate immunity, with a focus on parasite evasion of the human innate immune system.
Topics: Host-Pathogen Interactions; Humans; Immune Evasion; Immunity, Innate; Toxoplasma; Toxoplasmosis
PubMed: 31041194
DOI: 10.3389/fcimb.2019.00103 -
The Journal of Clinical Investigation Jul 2020Toxoplasma gondii is an incredibly successful parasite owing in part to its ability to persist within cells for the life of the host. Remarkably, at least 350 host... (Review)
Review
Toxoplasma gondii is an incredibly successful parasite owing in part to its ability to persist within cells for the life of the host. Remarkably, at least 350 host species of T. gondii have been described to date, and it is estimated that 30% of the global human population is chronically infected. The importance of T. gondii in human health was made clear with the first reports of congenital toxoplasmosis in the 1940s. However, the AIDS crisis in the 1980s revealed the prevalence of chronic infection, as patients presented with reactivated chronic toxoplasmosis, underscoring the importance of an intact immune system for parasite control. In the last 40 years, there has been tremendous progress toward understanding the biology of T. gondii infection using rodent models, human cell experimental systems, and clinical data. However, there are still major holes in our understanding of T. gondii biology, including the genes controlling parasite development, the mechanisms of cell-intrinsic immunity to T. gondii in the brain and muscle, and the long-term effects of infection on host homeostasis. The need to better understand the biology of chronic infection is underscored by the recent rise in ocular disease associated with emerging haplotypes of T. gondii and our lack of effective treatments to sterilize chronic infection. This Review discusses the cell types and molecular mediators, both host and parasite, that facilitate persistent T. gondii infection. We highlight the consequences of chronic infection for tissue-specific pathology and identify open questions in this area of host-Toxoplasma interactions.
Topics: Animals; Disease Models, Animal; History, 20th Century; History, 21st Century; Humans; Toxoplasma; Toxoplasmosis
PubMed: 32609097
DOI: 10.1172/JCI136226 -
Clinical Microbiology Reviews Apr 1998Infections by the protozoan parasite Toxoplasma gondii are widely prevalent world-wide in animals and humans. This paper reviews the life cycle; the structure of... (Review)
Review
Infections by the protozoan parasite Toxoplasma gondii are widely prevalent world-wide in animals and humans. This paper reviews the life cycle; the structure of tachyzoites, bradyzoites, oocysts, sporocysts, sporozoites and enteroepithelial stages of T. gondii; and the mode of penetration of T. gondii. The review provides a detailed account of the biology of tissue cysts and bradyzoites including in vivo and in vitro development, methods of separation from host tissue, tissue cyst rupture, and relapse. The mechanism of in vivo and in vitro stage conversion from sporozoites to tachyzoites to bradyzoites and from bradyzoites to tachyzoites to bradyzoites is also discussed.
Topics: Animals; Cells, Cultured; Host-Parasite Interactions; Humans; Immunohistochemistry; Life Cycle Stages; Microscopy, Electron; Toxoplasma; Toxoplasmosis; Toxoplasmosis, Animal
PubMed: 9564564
DOI: 10.1128/CMR.11.2.267 -
The Journal of Eukaryotic Microbiology Nov 2022Toxoplasma gondii is an obligate intracellular parasite and the causative agent of Toxoplasmosis. A key to understanding and treating the disease lies with determining... (Review)
Review
Toxoplasma gondii is an obligate intracellular parasite and the causative agent of Toxoplasmosis. A key to understanding and treating the disease lies with determining how the parasite can survive and replicate within cells of its host. Proteins released from specialized secretory vesicles, named the dense granules (DGs), have diverse functions that are critical for adapting the intracellular environment, and are thus key to survival and pathogenicity. In this review, we describe the current understanding and outstanding questions regarding dense granule biogenesis, trafficking, and regulation of secretion. In addition, we provide an overview of dense granule protein ("GRA") function upon secretion, with a focus on proteins that have recently been identified.
Topics: Humans; Toxoplasma; Protozoan Proteins; Toxoplasmosis; Virulence
PubMed: 35302693
DOI: 10.1111/jeu.12904 -
Frontiers in Cellular and Infection... 2019is a successful protozoan parasite that cycles between definitive felid hosts and a broad range of intermediate hosts, including rodents and humans. Within intermediate... (Review)
Review
is a successful protozoan parasite that cycles between definitive felid hosts and a broad range of intermediate hosts, including rodents and humans. Within intermediate hosts, this obligate intracellular parasite invades the small intestine, inducing an inflammatory response. infects infiltrating immune cells, using them to spread systemically and reach tissues amenable to chronic infection. An intact immune system is necessary to control life-long chronic infection. Chronic infection is characterized by formation of parasite cysts, which are necessary for survival through the gastrointestinal tract of the next host. Thus, must evade sterilizing immunity, but still rely on the host's immune response for survival and transmission. To do this, exploits a central cost-benefit tradeoff in immunity: the need to escalate inflammation for pathogen clearance vs. the need to limit inflammation-induced bystander damage. What are the consequences of sustained inflammation on host biology? Many studies have focused on aspects of the immune response that directly target growth and survival, commonly referred to as "resistance mechanisms." However, it is becoming clear that a parallel arm of the immune response has evolved to mitigate damage caused by the parasite directly (for example, egress-induced cell death) or bystander damage due to the inflammatory response (for example, reactive nitrogen species, degranulation). These so-called "disease tolerance" mechanisms promote tissue function and host survival without directly targeting the pathogen. Here we review changes to host metabolism, tissue structure, and immune function that point to disease tolerance mechanisms during infection. We explore the impact tolerance programs have on the health of the host and parasite biology.
Topics: Animals; Disease Resistance; Host-Parasite Interactions; Humans; Immune Tolerance; Immunity, Innate; Inflammation; Toxoplasma; Toxoplasmosis
PubMed: 31245299
DOI: 10.3389/fcimb.2019.00185 -
F1000Research 2018is an obligate intracellular parasite belonging to the phylum Apicomplexa that infects all warm-blooded animals, including humans. can replicate in every nucleated... (Review)
Review
is an obligate intracellular parasite belonging to the phylum Apicomplexa that infects all warm-blooded animals, including humans. can replicate in every nucleated host cell by orchestrating metabolic interactions to derive crucial nutrients. In this review, we summarize the current status of known metabolic interactions of with its host cell and discuss open questions and promising experimental approaches that will allow further dissection of the host-parasite interface and discovery of ways to efficiently target both tachyzoite and bradyzoite forms of , which are associated with acute and chronic infection, respectively.
Topics: Animals; Host-Parasite Interactions; Humans; Toxoplasma; Toxoplasmosis
PubMed: 30467519
DOI: 10.12688/f1000research.16021.1 -
Microbiology Spectrum Jun 2023Many RNA modifications have been detected in rRNA, tRNA and small noncoding RNA (sncRNA) as well as in low-abundance RNA species such mRNA. Although RNA modifications...
Many RNA modifications have been detected in rRNA, tRNA and small noncoding RNA (sncRNA) as well as in low-abundance RNA species such mRNA. Although RNA modifications play roles in many cellular and biological processes in various domains of life, knowledge about the diversity and role of RNA modifications in Toxoplasma gondii is limited. In this study, RNA modifications in three T. gondii strains (RH type I, PRU type II, and VEG type III) with distinct virulence abilities were determined by liquid chromatography-tandem mass spectrometry. We compared the levels of modifications of four nucleotides in tRNA and sncRNA, characterized RNA modification patterns of different T. gondii strains, and determined the diversity of RNA modifications. We detected and quantified 22 modified nucleosides in both tRNA and sncRNA. Significant differences in the diversity of the modified nucleosides were found between the three T. gondii strains. RNA modifications were correlated with the expression of many T. gondii virulence proteins. Some of the identified modifications (e.g., 2'-O-methylinosine, pseudouridine) play a role in mediating the host-parasite interaction. These results provide novel insight into the global modifications in tRNA and sncRNA, and the diversity of RNA modifications between T. gondii strains with different virulence backgrounds. Although RNA modifications play roles in many cellular and developmental processes in various domains of life, knowledge about the patterns and functions of RNA modifications in T. gondii is limited. Here, a quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach was used to study global RNA modifications in T. gondii strains of distinct virulence backgrounds. We quantified 22 modified nucleosides in both tRNA and sncRNA. Significant T. gondii strain-specific differences in RNA modifications were detected. More tRNA modifications correlated with T. gondii virulence proteins than sncRNA modifications. RNA modifications were significantly correlated with virulence proteins. Our data provide the first comprehensive profiling of the modifications tRNA and sncRNA in T. gondii, expanding the diversity of RNA modifications in this parasite and suggesting new regulators for modulating its virulence.
Topics: Toxoplasma; Tandem Mass Spectrometry; Chromatography, Liquid; RNA, Small Untranslated; Nucleosides; RNA, Transfer; Protozoan Proteins
PubMed: 37036375
DOI: 10.1128/spectrum.03564-22