What are CRISPR Capsules?

Our team is investigating the utility of outer membrane vesicles (OMVs) in the delivery of the Cas9-complex. All Gram-negative bacteria produce OMVs and use them to deliver toxins, communicate with other bacteria, mediate membrane composition, and extract materials such as metal ions from their environment. OMVs have been successfully engineered to carry heterologous proteins 1, which makes them an attractive candidate for systems that require the delivery of a functional protein or complex to recipient cells.

Why do they matter?

One application of CRISPR-Cas9 is that of treating antibiotic-resistant bacterial infections; however, in order for Cas9 to do its work, it has to get to the site of infection first. At the moment the most effective methods of delivering Cas9 to target cells are either limited to DNA delivery (bacteriophage delivery 2 and hydrodynamic injection 3) or require extensive vector engineering in order to facilitate controlled delivery and uptake (lipid-mediated transfection 4).

We hope to use signal peptides and protein fusions to direct Cas9 protein into OMVs so that the functional complex can be delivered to and act on the resistance genes in antibiotic-resistant bacteria without extensive lipid modification to facilitate uptake. With sufficient further development, CRISPR Capsules could be used in conjunction with traditional antibiotics to allow treatment of resistant infections.

Northwestern University
Technological Institute
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Evanston, IL 60208