Abstract
Toxoplasma gondii is a ubiquitous parasitic protist found in a wide variety of hosts, including a large proportion of the human population. Beyond an acute phase which is generally self-limited in immunocompetent individuals, the ability of the parasite to persist as a dormant stage, called bradyzoite, is an important aspect of toxoplasmosis. Not only is this stage not eliminated by current treatments, but it can also reactivate in immunocompromised hosts, leading to a potentially fatal outcome. Yet, despite its critical role in the pathology, the bradyzoite stage is relatively understudied. One main explanation is that it is a considerably challenging model, which essentially has to be derived from in vivo sources. However, recent progress on genetic manipulation and in vitro differentiation models now offers interesting perspectives for tackling key biological questions related to this particularly important developmental stage.
Highlights
Toxoplasma gondii is a parasite whose life cycle classically includes transmission from definitive hosts, in which sexual reproduction occurs, to intermediate hosts, in which it multiplies asexually [1] (Figure 1). This parasite has an unparalleled range of intermediate hosts: it is believed to infect up to a third of the world’s human population as well as a broad variety of animal species
Transmission from definitive hosts to intermediate hosts is mediated by oocysts shed by the former in the environment
The parasites differentiate into an asexually-dividing form called tachyzoite, whose rapid replication and spread within the body of the intermediate host may cause a disease called toxoplasmosis [3]
Summary
Toxoplasma gondii is a parasite whose life cycle classically includes transmission from definitive hosts (felids), in which sexual reproduction occurs, to intermediate hosts (warm-blooded vertebrates), in which it multiplies asexually [1] (Figure 1). In healthy and immunocompetent individuals, tachyzoites are not completely eliminated by the immune system, but they differentiate into slowly-growing bradyzoite forms, establishing within tissue cysts, primarily in the central nervous system and muscle [5] This persistent chronic form of the pathogen may remain for a long time in the host (perhaps throughout its life [6]), which is a major concern as it may reactivate and lead to a severe pathology in the event of a weakened immune system. The classical completion of the cycle includes predation of an intermediate host by felids, and ingestion of parasite-containing tissue cysts They differentiate into sexually-competent stages that lead to the formation of the oocysts that are shed by the felid in the environment to start another cycle [1]. We summarize important aspects of their differentiation and persistence mechanisms, as well as recent technical progress that will hopefully enable tackling some important biological questions related to this developmental stage in the near future
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
