A genome-writing consortium announced today that it intends to revise the genome of human cells in the lab so they resist viruses.

What’s recoding? A person’s genome uses three-letter “codons” (think AGT or CAT) to direct the assembly of proteins. But it turns out there are extra codons that aren’t needed. The plan is simple: get rid of them. That’s going to take some heavy-duty gene editing—more than 400,000 changes to about 20,000 human genes.

Who’s behind it: The project is the first big announcement by GP-Write, a private organization trying to hurry us up to the point where we can easily print human genomes. So far it lacks serious funding, but a gene-editing company, Cellectis, says it will donate its technology to the cause. The effort is expected to take about a decade.

Bad for viruses: Viruses use the missing codons to propagate in cells, so a recoded cell would be essentially virus-proof. The researchers say such “ultra-safe” cells could be good for the biotech industry, which uses human cells to manufacture drugs.

Are virus-proof people coming? That’s certainly a possibility, according to project leader George Church of Harvard Medical School. He once wrote that recoded humans would be the “climax” of synthetic biology.