Parasites are targets for genome editing

There was a paper last week in Nature by the Striepen lab at the University of Georgia, showing that the well-known CRISPR system could be used to study an important human pathogen, Cryptosporodium parvum. The protozoan parasite causes diarrhea in children and in immunocompromised individuals (the image shows the parazites in the epithelial vacuoles of the intestine). Studying this parasite remains challenging due to lack of efficient propagation methods, simple animals models and molecular genetic manipulation techniques. Despite inefficient transfection, CRISPR/Cas9 along with a drug resistance cassette, rendered the parazites drug-resistant. Interestingly, non-homologous end-joining, a common error-prone DNA repair mechanism in higher organisms, is completely absent in Cryptosporodium. In contrast, homology-directed repair can lead to modifications in the genome when linked to Cas9 nuclease activity. The advance of this technique is that genetically modified parasites could be propagated and placed under selection pressure and in vivo. This would faciliate drug screening, drug target validation, but might also lead to the development of genetically modified, attenuated parasites for vaccination.

You can access the paper here: http://www.nature.com/nature/journal/v523/n7561/full/nature14651.html