Cell structure and metabolism of the parasite Toxoplasma gondii - new aspects. The article is based on newly published data concerning cell structure (cytoskeleton and cytoplasmic organelle) and biochemistry of the protozoon Toxoplasma gondii, many of which can be applied in therapy of toxoplasmosis.
The 2016 Nobel Prize in Physiology or Medicine was awarded to molecular biologist Yoshinori Ohsumi for his work in the field of autophagy (Greek for “self eating”). This fact has once again directed the attention of many scientists to a common cellular phenomenon occurring in all eukaryotes from yeast to mammals, namely the process by which the cell digests and then recycles its components. Although the phenomenon of autophagy was discovered in mammals, a method for monitoring it by light microscopy was established in the unicellular eukaryote, the budding yeast Saccharomyces cerevisiae. The article describes the achievements of the Nobel Laureate, the mechanism of autophagy and its role in the cell physiology of organisms including the unicellular pathogen, the protozoan Toxoplasma gondii.
Toxoplasma gondii -intracellular parasite. Tue article presents selected data concerning invasion and intracellular life of obligate intracellular parasite Toxoplasma gondii in susceptible bosts.
The protozoan Toxoplasma gondii is believed to be a common parasite of almost all endothermic animals and humans. However, recent reports of toxoplasmosis in marine mammals raise concern that cold-blooded animals may also be a potential source of T. gondii infection. The article discusses the presence of T. gondii in aquatic and terrestrial poikilothermic animals, which may be important elements in the transmission of the parasite.
The protozoan Toxoplasma gondii, described by Nicolle and Manceaux in 1908, is a ubiquitous and cosmopolitan parasite that infects a wide range of mammal and bird species with high prevalence. The biological success of T. gondii is associated with the formation of a specific relationship between the parasite and host cells leading to the establishment of a latent, chronic infection. During primary infection, acquired mostly by the oral route, the quickly multiplying tachyzoites disseminate through the body crossing several structural-functional barriers as bloodbrain or blood-retina, then they transform into dormant bradyzoites which, enclosed in tissue cysts, occupy preferentially the brain, skeletal muscle and eye. Although T. gondii is able to infect all kinds of nucleated cells, it uses strictly defined host cells, dependent on the life-cycle phase and infection stage. The article discusses selected aspects of the parasite passing via the host body barriers as well as particular role of dendritic cells and skeletal muscle cells, used by the parasite as an very effective vehicle to disseminate throughout the host body or the site of long-term T. gondii persistence, respectively.
Mast cells, discovered by Paul Burnet over one century ago, have been long recognized only as inductors of IgE-dependent allergic diseases (allergy of type I, Th2 lymphocytes dependent). However, numerous recent studies have indicated that they play an essential role in many other immunological and non-immunological processes. Infection with Toxoplasma gondii elicits the induction of a strong cell-mediated immunity characterized by a highly-polarized Th1 response, which can protect against allergy. Knowledge of the contribution of mast cells to Toxoplasma invasion is still limited, and the present article discusses aspects of the relationship between mast cells and T. gondii.
Toxoplasma gondii, the etiological agent of toxoplasmosis, is an Apicomplexa obligate intracellular protozoan parasite, which is able to infect any nucleated cell of numerous endothermic vertebrates. The combined abilities to actively penetrate host cells and perfectly control the fate of the parasite-containing vacuole (parasitophorus vacuole, PV) contribute to the remarkable global success of Toxoplasma as an intracellular parasite. Very broad host range and the relative ease of growth both in cell cultures in vitro and in vivo suggest that the parasite is able to manipulate the host cell apoptotic machinery. The article describes different aspects of host-parasite interplay focusing on molecular modifications of infected host cells.
The basic premise of vaccinology is to achieve strong protective immunity against defined infectious agents by a vaccine mimicking the effects of natural primary exposure to a pathogen. Because an exposure of humans and animals to microbes occurs mostly through mucosal surfaces, targeting the mucosa seems a rational and efficient vaccination strategy. Many experimental and clinical data confirmed that mucosal immunization offers many advantages over widely used in human and veterinary medicine subcutaneous or intramuscular immunization. In the present article selected aspects regarding mucosal vaccination are discussed. The structure and function of mucosaassociated lymphoid tissue (MALT), comprised of four main mucosal compartments forming a structural and functional unity as well as pivotal cellular MALT components (dendritic and M cells) were briefly characterized. Particular attention was focused on the mode of simple but efficacious delivery of vaccine antigens to mucosal surfaces. A few trials to generate potential mucosal vaccines against toxoplasmosis introduced by nasal or oral routes to experimental animals are also presented.
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