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

## TL;DR

This study finds that heating Toxoplasma gondii cysts to 60°C for 10 minutes kills them, preventing infection in mice and improving meat safety.

## Contribution

The study establishes a precise thermal threshold for inactivating T. gondii cysts using a multi-parameter infectivity assessment in mice.

## Key findings

- Treatment at 60°C for 10 minutes completely abolishes T. gondii cyst infectivity.
- Infected mice showed 100% survival, no antibodies, and no parasite DNA or lesions after treatment.
- The findings provide a science-based reference for thermal processing guidelines to enhance meat safety.

## Abstract

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.

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•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.

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.