Toxoplasma gondii metacaspase 2 is an important factor that influences bradyzoite formation in the Pru strain


Toxoplasma gondii is an important zoonotic protozoan of the phylum Apicomplexa that can infect nearly all warm-blooded animals. The parasite can exist as the interconvertible tachyzoite or bradyzoite forms, leading to acute or latent infection, respectively. No drug has been reported to penetrate the cyst wall and reduce bradyzoite survival and proliferation till now. The transcriptional level of metacaspases 2 (TgMCA2) in T. gondii is significantly upregulated during the formation of bradyzoites in the Pru strain, indicating that it may play an important role in the formation of bradyzoites. To further explore the function of TgMCA2, we constructed a TgMCA2 gene-knockout variant of the Pru strain (Δmca2). Comparative analysis revealed that the proliferative capacity of Pru Δmca2 increased, while the invasion and egressing properties were not affected by the knockout. Further data shows that the tachyzoites of Δmca2 failed to induce differentiation and form bradyzoites in vitro, and the transcriptional levels of some of the bradyzoite-specific genes (such as BAG1, LDH2, and SAG4A) in Δmca2 were significantly lower compared with that in the Pru strain at the bradyzoite stage. In vivo, no cysts were detected in Δmca2-infected mice. Further determination of parasite burden in Δmca2- and Pru-infected mice brain tissue at the genetic level showed that the gene load was significantly lower than that in Pru. In summary, we confirmed that TgMCA2 contributes to the formation of bradyzoites, and could provide an important foundation for the development of attenuated vaccines for the prevention of T. gondii infection.

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Data availability

All datasets generated for this study are included in the manuscript/supplementary files.



T. gondii type II Prugniuad (Pru) strains



Δmca2 :

TgMCA2 gene-knockout variant of the Pru strain


bradyzoite-specific gene 1


lactate dehydrogenase 2


surface antigen protein 4A


human foreskin fibroblasts


fetal bovine serum


Dulbecco’s modified Eagle’s medium


dihydrofolate reductase


immunofluorescence assay


cyst wall glycoprotein


bradyzoite pseudokinase


nucleotide sugar transporter


dense granular proteins


rhoptry proteins


transcription factors


Myb-like transcription factor




calcium-dependent protein kinase


eukaryotic initiation factor


protein kinase A catalytic subunit 3


vacuolar compartment




chloroquine resistance transporter


inner membrane complex 1


glideosome-associated protein 45


parasitophorous vacuole


surface antigen 1


Dolichos biflorus agglutinin




TgMCA2-deficient complementary strain


uracil phosphoribosyltransferase


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We would like to show our appreciation to Yong Fu, Xiao Zhang, and Ying Xu (China Agricultural University, China) for their help and suggestions.

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This study was supported by the National Key Research and Development Program of China (2017YFD0501304) and the National Natural Science Foundation of China (31672544, 31730096,81971964).

Author information




LQ, LJ, and LMY conceived and designed the study. LMY and LMZ performed the experiments. SXJ analyzed the data and drafted the manuscript. YX and LJ helped in manuscript writing. All authors read and approved the final manuscript.

Corresponding authors

Correspondence to Jing Liu or Qun Liu.

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Our research with all animals were approved by the Beijing Laboratory Administration Committee in accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the Ministry of Science and Technology of China (Approval No.: 18049). The mice were humanely euthanized when they reached the end of the experiment.

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Song, X., Lin, M., Li, M. et al. Toxoplasma gondii metacaspase 2 is an important factor that influences bradyzoite formation in the Pru strain. Parasitol Res 119, 2287–2298 (2020).

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  • Toxoplasma gondii
  • Differentiation
  • Bradyzoite
  • Cyst
  • Metacaspase 2
  • Bradyzoite-specific genes