Systematic identification of Toxoplasma gondii virulence factors

How eukaryotic parasites like Toxoplasma gondii survive the host immune response and disseminate to distant organs is poorly understood. Toxoplasma co-opts the host cell by secreting proteins from specialized organelles called rhoptries (ROPs) and dense granules (GRAs). However, most ROPs and GRAs have unknown functions. I used a CRISPR/Cas9 based in vitro and in vivo loss of function screens to identify; GRA45, a Toxoplasma gene product that determines its fitness in IFNγ-stimulated murine macrophages, and a Toxoplasma gene product called TgWIP (Toxoplasma gondii WAVE complex Interacting Protein) that is important for its in vivo dissemination.