We took advantage of rAAV’s natural ability to amplify the cell's own high fidelity DNA repair pathway - homologous recombination - by 1,000X to 10,000X. In this way we were able to create our first cell lines - cells containing precisely engineered, disease associated mutations for some of the most extensively studied oncology genes, such as KRAS, PIK3CA and BRAF.
rAAV is a wonderfully precise system - any clones containing off-target integrations could be quickly identified and discarded - but despite the improvements in efficiency over plasmid, we would still routinely have to screen thousands of clones for every gene editing experiment to find a positive.
As such in 2013 Horizon began licensing nuclease-based genome editing technologies to improve our efficiencies still further - at first Zinc Finger Nucleases (ZFNs), and then CRISPR Cas9 gene editing.
These nucleases create a double-stranded DNA break at the target site and activate the cells DNA repair pathways, which can not only dramatically improve the efficiency of homologous recombination, but can also be used to rapidly and efficiently knockout genes through error prone repair.
It is this mechanism that Horizon has used to systematically generate our extensive collection of knockout cell lines, and to produce a number of scientific firsts for in vivo genome editing, including knockout rat models to further study of neuroscience including conditions like Autism, Parkinson's and Alzheimer's.
At Horizon we can now select the most appropriate tool for each individual gene editing project, whether it's CRISPR-Cas9, ZFN or rAAV. Each of these approaches has its own features and strengths revolving around precision, efficiency, flexibility and even IP landscape. We continue to improve our processes still further through internal technology development or in-licensing new technology where appropriate, all of which mean we can offer an unmatched service for all your gene editing needs.
Alternatively if you'd like to learn more about gene editing, what it is and what you can use it for, you can now read our complete guide or watch our series of webinars.