Normally when we think of viruses, we think of how they make us sick and miserable. But what if we could make viruses work for us, instead of against us? That’s exactly what John Hales and his team did at University College London: They took viruses and turned them into lasers.

While this sounds like a sci-fi villain’s dream, it promises to be a force for good. Hales’ group works on bacteriophages, a type of virus that only infects bacteria. They have engineered a specific type of bacteriophage to express a fluorescent dye on their protein coat: in other words, they literally glow, allowing scientists to track them. These phages can be programmed to attach to a broad array of targets such as proteins and DNA. 

The florescent dye is what makes the virus a laser. Once inside the target, the virus can emit a detectable pulse of light, making it really easy to find the protein or DNA region of interest. 

An important application of this technology is in blood and urine  diagnostics. When tested, the viral lasers could clearly detect clinically relevant concentrations of antibodies. This exciting marriage of synthetic biology and physics is still being optimized in the lab, but it may one day replace the current diagnostic tools in clinics and doctors’ offices.