Our immune system cannot always make antibodies —proteins that surround and deactivate pathogens— quickly enough to neutralize aggressive viruses. Vaccines prime the system to build antibodies before infection, but they can be expensive to develop, slow to produce, or elusive. In March chemists created a promising alternative: a synthetic antibody that can disable a pathogen in a living animal.
Ken Shea and colleagues at the University of California, Irvine, used melittin, the toxin in bee venom, as the antigen (the substance triggering an immune reaction). Melittin particles hold a positive charge, so Shea created a negatively charged polymer. He added melittin so the polymer particles formed with a molecular imprint of the toxin’s shape. The plastic nanoparticle attracted the toxin and fit it like a cast, neutralizing it.
Shea gave mice a lethal dose of melittin, then injected half the animals with his plastic antibodies. All the unprotected mice died, but almost 60 percent of the treated ones survived. The experiment shows how antibodies might be built quickly in the lab, “a decided advantage if some unknown horrible disease might appear,” Shea says.