• Otávio Santiago

CRISPR-Based Tech Could Revolutionize Antibody-Based Diagnostics

Scientists have used an adaptation of the genome editing technology CRISPR to develop a new peptide display platform that can be used as a tool to identify antibodies in patient blood samples. Researchers from the Howard Hughes Medical Institutes and Harvard Medical School suggest the new technology, which they’ve called PICASSO (peptide immobilization by Cas9-mediated self-organization), could inspire a new class of medical diagnostics, and springboard a host of other applications.

For their reported study in Molecular Cell, which is titled, “CRISPR-based peptide library display and programmable microarray self-assembly for rapid quantitative protein binding assays,” the investigators used the platform to detect antibodies binding to proteins derived from pathogens, including SARS-CoV-2 from the blood of recovering COVID-19 patients. The work was led by Stephen Elledge, PhD, at Harvard Medical School and Brigham and Women’s Hospital. The paper’s first author, Karl Barber, PhD, is a 2018 Schmidt science fellow, with much of the work developing the technology taking place during his fellowship research placement in corresponding author Elledge’s laboratory.

CRISPR-Cas9 technology has been adapted for a range of applications in precise genome editing and transcriptional regulation, which has enabled scientists to effectively manipulate genetic sequences “at will,” the authors noted. But the ability of different Cas nuclease enzymes to recognize and respond to nucleic acid sequences complementary to their bound single-guide RNAs (sgRNAs) has also “further inspired the development of in vitro CRISPR-based technologies,” including rapid point-of-care pathogen identification and nucleic acid-responsive smart hydrogels. “CRISPR-inspired systems have been extensively developed for applications in genome editing and nucleic acid detection,” they noted.

The PICASSO technology developed by Barber and colleagues uses a modified Cas9 enzyme to facilitate the study of custom peptide libraries and overcome the limitations of current display technologies. “In developing PICASSO, we have demonstrated multiplexed peptide library self-assembly using a CRISPR-based system, making rapid custom protein studies feasible in any laboratory with access to common molecular biology reagents,” they wrote. The PICASSO approach harnesses customizable collections of proteins, which are attached to a catalytically inactive Cas9 enzyme (dCase9). This variant will bind to DNA, but not cut it, as it would for genetic modification applications. The peptide collections are fused to the dCAS9, and barcoded with unique single guide RNA (sgRNA) sequences.

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