Decoy particles trick coronavirus as it evolves

As the ever-evolving SARS-CoV-2 virus begins to evade once promising treatments, such as monoclonal antibody therapies, researchers have become more interested in these "decoy" nanoparticles. Mimicking regular cells, decoy nanoparticles soak up viruses like a sponge, inhibiting them from infecting the rest of the body.

In a new study, Northwestern University synthetic biologists set out to elucidate the design rules needed make decoy nanoparticles effective and resistant to viral escape. After designing and testing various iterations, the researchers identified a broad set of decoys – all manufacturable using different methods – that were incredibly effective against the original virus as well as mutant variants.

Although much more research and clinical evaluations are needed, the researchers believe decoy nanoparticle infusions someday could potentially be used to treat patients with severe or prolonged viral infections. "We showed that decoy nanoparticles are effective inhibitors of all these different viral variants," said Northwestern's Joshua Leonard, co-senior author of the study. "Even variants that escape other drugs did not escape our decoy nanoparticles."

To design decoy nanoparticles, the Northwestern team used nanosized particles (extracellular vesicles) naturally released from all cell types. They engineered cells producing these particles to overexpress the gene for ACE2, leading to many ACE2 receptors on the particles' surfaces. When the virus came into contact with the decoy, it bonded tightly to these receptors rather than to real cells, rendering the virus unable to infect cells.