Toxoplasma gondii: Laboratory Maintenance and Growth.

Toxoplasma gondii is a highly successful apicomplexan protozoan capable of infecting any warm-blooded animal worldwide. In humans, Toxoplasma infections are life-long, with approximately one-third of the world's population chronically infected. Although normally controlled by the host immune system, T. gondii infection can lead to a variety of clinical outcomes in individuals with immature or suppressed immune systems. After penetrating the intestine, parasites rapidly disseminate throughout the body and stimulate production of the cytokines interleukin (IL)-12, IL-18, and interferon (IFN)-γ by immune cells. These cytokines play a key role in host resistance to T. gondii by promoting a strong Th1 response. Recent reports show that gut commensal bacteria can act as molecular adjuvants during T. gondii infection. Thus, T. gondii is an excellent model system to study host-pathogen interactions. This unit outlines the protocols for in vitro and in vivo maintenance and growth of T. gondii. © 2017 by John Wiley & Sons, Inc.