SBIR-STTR Award

Toxoplasma gondiistrain T-263 is an oocyst negative genetic mutant that induces immunity in cats to wild type strains when tissue cysts or bradyzoites are administered orally. The vaccine potential of T-263 has been proven in two separate efficacy studies. Use of this feline vaccine will reduce oocyst contamination of homes and surroundings thereby reducing zoonotic toxoplasmosis in humans. Production of the vaccine in @ce is economically and practically unacceptable. Thus, commercialization depends on the development of an economic method for the production of tissue cystsibradyzoites. The overall objective is to demonstrate the feasibility of producing T-263 tissue cysts (containing bradyzoites) in cell culture. A laboratory-scale cell culture system will be optimized for maximal cyst production by using strategies to prevent cell destruction by tachyzoites and to enhance cyst persistence. The feasibility of genetic selection for enhanced tissue cyst formation in cell culture will also be evaluated. This will lead directly into the Phase II program of process scale-up and downstream processing development. This novel production technology will have immediate application to the commercialization of the T-263 vaccine.Awardee's statement of the potential commercial applications of the research:The development of an economic and simple method for the production of Toxoplasma gondii bradyzoites has direct and immediate application to the commercialization of the T-263 vaccine for cats.National Institute of Allergy and Infectious Diseases (NIAID)

Immunity to wild type Toxoplasma gondii may be induced in cats by bradyzoites of an oocyst negative strain, T263. A feline vaccine based on this premise would serve to reduce toxoplasmosis in humans by reducing environmental oocyst contamination. Successful commercialization of a vaccine depends on production of tissue cysts and bradyzoites in cell culture, the objective of Phase I. The bench scale method for tissue cyst production developed in Phase I will be scaled up for maximum production during Phase II. The process will be adapted to microcarrier cell culture and scaled up to batch production at the 5 liter bioreactor scale.National Institute of Allergy and Infectious Diseases (NIAID)