Toxoplasma gondii and the host cells.

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 blood-brain 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.