Factors Influencing Tissue Cyst Yield in a Murine Model of Chronic Toxoplasmosis

Cortni A. Troublefield, Joy S. Miracle, Robert D. Murphy, Ryan W. Donkin, Anthony P. Sinai

Research output: Contribution to journalArticlepeer-review


Recent advances into the unique biology of Toxoplasma tissue cysts and the bradyzoites they house necessitate optimization of tissue cyst recovery from infected mouse brains. Here, we present data from 83 tissue cyst purifications of Type II ME49 tissue cysts in CBA/J mice performed over a period of 3 years. The effects of infection with both tissue culture tachyzoites as well as ex vivo tissue cysts were assessed. Significant mortality was restricted to tachyzoite infections with female mice being more susceptible. Infection with tissue cysts was associated with both lower overall symptomology and mortality, exhibiting no sex bias. Cumulatively, host sex did not impact overall tissue cyst yields, although tachyzoite-initiated infections generated significantly higher yields compared to tissue cyst-initiated infections. Notably, serial passage of tissue cysts was accompanied with a decreasing trend for subsequent cyst recovery. The time of tissue cyst harvest, a potential reflection of bradyzoite physiological state, had no significant impact on subsequent cyst yield at the selected time points. In aggregate, these data reveal the considerable heterogeneity associated with tissue cyst yield, making the design of adequately powered experiments critical. This is particularly the case for drug studies where overall tissue cyst burden is currently the primary and often sole metric of efficacy, as the data presented here demonstrate that cyst recovery between preparations of untreated animals can mirror and even exceed the reported effects of drug treatment.

Original languageEnglish
JournalInfection and Immunity
Issue number7
StatePublished - Jul 2023

Bibliographical note

Funding Information:
This work is supported by the U.S. National Institutes of Health grants RO1AI145335 and R21 AI150631 awarded to A.P.S.

Publisher Copyright:
© 2023 Troublefield et al.


  • Toxoplasma gondii
  • bradyzoite
  • tissue cyst

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


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