Bioassay of the infectivity of heat-treated Toxoplasma gondii cysts in susceptible C57BL/6J mice

Toxoplasma gondii is a significant foodborne parasite. However, the precise thermal conditions required to inactivate its tissue cysts in meat remain poorly defined. This study systematically determined the effects of temperature (45–70 °C) and time (10–30 min) on cyst viability. Cysts treated under each condition were orally administered to susceptible C57BL/6J mice, and infectivity was comprehensively assessed through survival, clinical signs, serology (IgG), qPCR, and histopathology. Results demonstrated that treatment at 60 °C for 10 min or under more stringent conditions completely abolished infectivity, as evidenced by 100% survival, the absence of specific antibodies, and the non-detection of parasite DNA or lesions in tissues. Thus, 60 °C for 10 min is established as a critical inactivation threshold, providing a definitive reference for developing science-based thermal processing guidelines to enhance meat safety. • Establishes 60 °C for 10 min as the thermal threshold to inactivate T. gondii cysts. • A multi-parameter assessment confirms complete loss of cyst infectivity. • Oral infection in susceptible mice provides relevant data for food safety. • Findings directly inform thermal processing guidelines for meat safety.