New Tools for Apicomplexan Parasite Research

Apicomplexan parasites cause significant morbidity and mortality to humans and livestock animals, and share characteristic morphological features, cytoskeletal components, and mechanisms of replication, motility and invasion. Understanding these mechanisms of infection and pathogenesis requires novel tools that support and further research.

Recently described methods of conditional gene deletion in the apicomplexan parasites Toxoplasma gondii and Plasmodium falciparum, the agents of toxoplasmosis and malaria, respectively, enable reliable gene function and virulence research using the dimerizable Cre (DiCre) strategy.1,2,3 BEI Resources now houses Toxoplasma gondii, strain RHΔku80::DiCre:T2A:CAT (NR-51627) and Plasmodium falciparum, strain NF54::DiCre (MRA-1314; Coming Soon), stable cell lines that express rapamycin-inducible Cre recombinase, thus allowing the conditional deletion of essential and non-essential parasite genes at different life cycle stages.3 These strains offer new opportunities to study genes impacting growth or stage conversion with applications in drug development and vaccination strategies.

Additional tools available from the BEI Resources catalog to support apicomplexan research include molecular standards for the development of quantitative PCR (qPCR) assays against babesiosis, an emergent tickborne parasitic disease that can also be transmitted by blood transfusion. These standards harbor the internal transcribed spacer (ITS) 1, 5.8S ribosomal RNAgene, ITS 2 regions from Babesia microti, strain GI (NR-50741) and Babesia duncani, strain WA1 (NR-50742), the most prevalent agents of babesiosis in the United States. As qPCR assays have become more commonplace in the diagnosis of parasitic infections, these standards are useful in the execution of highly specific and sensitive blood tests using droplet digital or real time PCR technologies.4

BEI Resources No.       Product Description
NR-50741 Plasmid pUC19 Containing the ITS 1, 5.8S rRNA Gene, ITS 2 Region from Babesia microti, Strain GI
NR-50742 Plasmid pUC19 Containing the ITS 1, 5.8S rRNA Gene, ITS 2 Region from Babesia duncani, Strain WA1
NR-51627 Toxoplasma gondii, strain RHΔku80::DiCre:T2A:CAT
MRA-1314 Plasmodium falciparum, strain NF54::DiCre – Coming Soon



  1. Hunt, A., et al. “Differential Requirements for Cyclase-Associated Protein (CAP) in Actin-Dependent Processes of Toxoplasma gondii.” ELife 8 (2019): e50598. PubMed: 31577230.
  2. Tibúrcio, M., et al. “A Novel Tool for the Generation of Conditional Knockouts to Study Gene Function across the Plasmodium falciparim Life Cycle.” mBio 10 (2019): e01170-19. PubMed: 31530668.
  3. Jullien, N., et al. “Conditional Transgenesis Using Dimerizable Cre (DiCre).” PLoS One 2 (2007): e1355. PubMed: 18159238.
  4. Wilson, M. et al. “Development of Droplet Digital PCR for the Detection of Babesia microti and Babesia duncani.” Exp. Parasitol. 149 (2015): 24-31. PubMed: 25500215.

Image:  Fluorescence microscopy of Toxoplasma gondii (PLoS Open-Access/Ke Hu and John M. Murray)

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