But Zhao and his colleagues at Melbourne’s Peter Doherty Institute for Infection and Immunity have envisioned a new application. Crispr can edit the genetic code—the biological instruction book that makes life possible—within the cells of every living being. “Cas13 can target these RNA viruses and inactivate them,” Zhao explained. Those are known segments of RNA that are found in virtually all flu strains and are crucial to the virus’s survival. Conventional antivirals such as Tamiflu only target particular strains of flu, which swiftly acquire resistance.