Research in the Sibley laboratory focuses on understanding the cellular microbiology of protozoan parasites, especially Toxoplasma gondii, which causes the common and sometimes debilitating infection toxoplasmosis.  We are also developing ways to study Cryptosporidium infection, a major cause of pediatric diarrheal disease in developing parts of the world.  These infections are often benign but can become life threatening in people with weakened immune systems.  One of the major focuses in the laboratory is to identify mechanisms that host cells use to inhibit intracellular parasites, and to define the molecular mechanisms used by parasites to block these pathways.  These studies have identified the major virulence determinants of the parasite and shown that they disrupt host signaling networks, alter gene expression, and impair immunity.  Finally, we are involved in several studies to define small molecules that target essential parasite functions as leads to developing new therapies.