A Genome-wide CRISPR Screen in Toxoplasma Identifies Essential Apicomplexan Genes

Saima M. Sidik, Diego Huet, Suresh M. Ganesan, My Hang Huynh, Tim Wang, Armiyaw S. Nasamu, Prathapan Thiru, Jeroen Saeij, Vern B. Carruthers, Jacquin C. Niles, Sebastian Lourido

Research output: Contribution to journalArticlepeer-review

348 Scopus citations


Apicomplexan parasites are leading causes of human and livestock diseases such as malaria and toxoplasmosis, yet most of their genes remain uncharacterized. Here, we present the first genome-wide genetic screen of an apicomplexan. We adapted CRISPR/Cas9 to assess the contribution of each gene from the parasite Toxoplasma gondii during infection of human fibroblasts. Our analysis defines ∼200 previously uncharacterized, fitness-conferring genes unique to the phylum, from which 16 were investigated, revealing essential functions during infection of human cells. Secondary screens identify as an invasion factor the claudin-like apicomplexan microneme protein (CLAMP), which resembles mammalian tight-junction proteins and localizes to secretory organelles, making it critical to the initiation of infection. CLAMP is present throughout sequenced apicomplexan genomes and is essential during the asexual stages of the malaria parasite Plasmodium falciparum. These results provide broad-based functional information on T. gondii genes and will facilitate future approaches to expand the horizon of antiparasitic interventions.

Original languageEnglish (US)
Pages (from-to)1423-1435.e12
Issue number6
StatePublished - Sep 8 2016


  • Apicomplexan parasites
  • eukaryotic pathogen
  • genome-wide CRISPR screen
  • host-cell invasion
  • host-pathogen interactions
  • malaria
  • toxoplasmosis

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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