CRISPR Approaches for Apicomplexans

The inherent difficulties in genetically manipulating parasites mean that there are real challenges in adopting any new technology. Adoption of gene editing technology has been slowed by technical problems and poor success rates in some labs that may reflect differences in reagents or experimental design, subtleties in protocols that are not apparent in the published literature, or genuine biological variability that may be dependent on factors such as the essentiality of the target or its location in the genome.

This retreat brought together the leading researchers who are implementing this technology to share our experience to move the field as a whole forward. The overall aim was to understand what factors are critical for success and, if possible, arrive at a common consensus on how we should standardise our experimental procedures across labs for more consistent success. In addition the retreat discussed:

1. the development and implementation of genome-wide approaches to targeting parasite biology. More broadly, we considered whether a systematically-generated gene knock-out resource in P. falciparum would be of value to the community, and if so, how this might be organised and implemented through an international collaborative effort.
2. the application of adapted CRISPR technology to efforts that could be broadly termed “genome targeting”. Such approaches employ repurposed Cas9 to deliver gene repression or activation domains, fluorescent proteins, or other functionalities to distinct sites on the genome. Although considerable progress in these areas has been made using mammalian systems, the evolutionary divergence of Apicomplexan parasites means that many of these functions are not easily transplantable. We also discussed the development of parasite-specific transcriptional activators, and how parasite histone modifying domains might be adapted for Cas9-driven local modification of chromatin structure to repress or activate gene expression.

Scientific programme committee