Viruses are often incredibly hard to treat. We’re certainly not strangers to that fact after the last few years. They’re extremely adaptable and very hard to destroy, making them very dangerous to human health. Antivirals can sometimes help a little, but usually—you get a virus, you’re stuck with it.

But what if instead of trying to treat these sneaky little beasts, we could stop them in their tracks before they even enter our cells? Create an organism that’s basically immune to viruses right off the bat? Well, geneticists at Harvard claim they’ve done just that.

In a recent study, a team of researchers announced that they had made an E. coli bacterium immune to all viruses. Well, all they could test in the lab, anyway.

“We can’t say it’s fully virus-resistant,” Akos Nyerges, genetics researcher and one of the authors of the study, said in a press release, “but so far, based on extensive laboratory experiments and computational analysis, we haven’t found a virus that can break it.”The researchers decided to take a “delete and trick” approach in the creation of their super-organism. They first went in and stripped the bacterium of three of its codons, which are little chunks of genetic code. And they didn’t just pick at random—they carefully deleted the codons that viruses latch onto to begin replicating themselves.

So, problem solved, right? Wrong.

It turns out that viruses can bring their own versions of these codons into the cell and bypass the deletions altogether, kind of like bringing a power adapter on an international trip so you can plug your devices into wrong-shaped outlets.

So, in step two, the scientists got a little tricky with RNA. Specifically with tRNA, or transfer RNA. When a virus is trying, to begin the replication process, it basically plugs a strand of tRNA into a codon, and the codon “prints” out an amino acid. That process creates proteins.

But critically, if the codons “print” the wrong amino acid, nothing gets made. You just get a string of gibberish instructions that halt the viral duplication process in its tracks. So, the researcher team inserted strands of tRNA into the E. coli that would tell the codons brought in by the viruses to produce the wrong amino acids. Theoretically, the virus could bring in it’s own tRNA too, but the researchers seem convinced that their tRNA strands win that fight.

With the codons now printing out completely wrong amino acids and the virus’s replication instructions being turned into nonsense, the infection was stopped before it even got started. With that success under their belt, the team eventually wants to use their new gene tech to create strands of virus-resistant bacteria that can be used to produce things like insulin.

And who knows? Maybe someday, we’ll be able to extend that tech to ourselves.