Last year, a Bioengineer assistant professor at Stanford University named Stanley Qi used a gene-editing tool called CRISPR, which flights influenza, to develop their own technique called Prophylactic Antiviral CRISPR in human cells. Also known as PAC-MAN, a team from Stanford University now works alongside Berkeley's Molecular Foundry to see if they can apply the same technique to fight against coronavirus.

As the first case of SARS-CoV-2, Qi and his team thought, 'Why don't we try using our PAC-MAN technology to fight it?' By late March, the Stanford scientists collaborated with Michael Connolly, an engineer of the Biological Nanostructures Facility at Berkeley Lab's Molecular Foundry, so they can develop a new system that can deliver PAC-MAN into patients' cells.

The first CRISPR system was discovered by Yoshizumi Ishino from Osaka University in 1987. Repeating clustered DNA was observed to have interruptions in what would typically be consecutively arranged.

By 2001, Ruud Jansen, searching for interrupted repeats, coined the term Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR). His observation of the prokaryote repeat cluster being accompanied by homologous genes resulted in cas genes.

PAC-MAN is made up of the enzyme Cas13, a virus killer, and a strand of guide RNA, which commands Cas13 to destroy specific nucleotide sequences in the coronavirus's genome. By re-arranging COVID-19's genetic code, PAC-MAN could neutralize it and stop it from replicating internal cells.

Delivery System

Qi explained that the primary challenge of translating PAC-MAN from a molecular tool into an anti-virus therapy is finding an effective way to deliver it into respiratory cells. As SARS-CoV-2 invades the lungs, infected air sacs become inflamed and filled with fluid, causing difficulty in breathing."But my lab doesn't work on delivery methods," he said, as the lab posted a tweet in hopes of finding the right collaboration.

By late March, they learned about Connolly's work on synthetic molecules, or lipitoids, and needed his expertise in cellular delivery techniques. Lipitoids are synthetic peptide mimics or peptoids. Connolly has worked with Ron Zuckermann, his mentor who discovered the peptoid, for 20 years to demonstrate 'lipitoids' effectiveness in the delivery of DNA and RNA to a wide variety of cell lines'

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International Collaboration

In May 2018, scientists studying lipitoids for potential therapeutic applications resulted that it is not harmful to the body and can deliver nucleotides by encapsulating them in nanoparticles the same size as a virus. Qi now hopes to add his CRISPR-based COVID-19 therapy to the Molecular Foundry's growing body of lipitoid delivery systems.

In late April, they tested a type of lipitoid, Lipitoid 1, which self-assembles with DNA and RNA into PAC-MAN carriers in a human epithelial lung cell sample. The initial trial went well as the SARS-CoV-2-targeting PAC-MAN reduced the synthetic solution by more than 90%. 'Berkeley Lab's Molecular Foundry has provided us with a molecular treasure that transformed our research,' Qi said.

Scientists from New York University and Karolinska Institute in Stockholm, Sweden will be joining the collaboration as they plan to test the PAC-MAN/lipitoid system in a live animal model infected with the virus. If successful, they may proceed to preclinical tests.

Conolly explained that 'an effective lipitoid delivery, coupled with CRISPR targeting, could enable a very powerful strategy for fighting viral disease not only against COVID-19 but possibly against newly viral strains with pandemic potential.' 'Everyone has been working around the clock trying to come up with new solutions," added Qi. 'It's very rewarding to combine expertise and test new ideas across institutions in these difficult times.'

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