Toxoplasma gondii is the zoonotic causative agent of toxoplasmosis, a disease of significant concern for pregnant persons and livestock. A member of the phylum Apicomplexa, Toxoplasma gondii can infect almost any cell type found in mammals and birds. There are multiple transmission pathways, including consumption of undercooked meat from infected animals, consumption of unwashed plants, contaminated water supplies, blood transfers, and congenital transfer. Felines are considered the definitive host of Toxoplasma gondii. Direct or indirect transmission can occur via contact with the stool of infected felines.

Researchers at the National Institute of Allergy and Infectious Diseases (NIAID), the U.S. Department of Agriculture (USDA), and the University of South Bohemia (Česke; Budějovice, Czechia) have demonstrated that T. gondii strains lacking expression of either the intracellular transport protein IFT88 or the CYS-6-type surface antigen SRS15B prevent the formation of oocysts and have potential for broad immunity to T. gondii. The inventors propose that mass inoculation of felines, specifically wild or feral felines, with a live vaccine developed from these strains could result in a significant reduction in oocyst production and environment contamination, reducing further infection in a geographical area. It is also proposed that loss of IFT88 or SRS15B homologs in other Apicomplexa parasites, like Neospora, Sarcocystis, or Cryptosporidium could have a similar impact.