What makes a soldier switch sides? That is a really good question. Especially when the soldier is an antibody that is supposed to defend the body against one of the world's most dangerous snake venoms, but instead ends up helping the venom kill the body.
The question has become topical after a group of DTU researchers slightly changed how they tested an antibody that had previously proven promising as an antidote to snake venom. In the first experiment on mice, the damaging effect on muscle tissue from the venom of Bothrops asper, a Costa Rican lancehead snake, was neutralized as expected. But in the second experiment, the antibody enhanced the snake venom's potency, so that it no longer just affected the muscle tissue, but ended up killing the mice.
When and how the antibody was administered made the difference between life and death. In the first experiment, snake venom and antibody were mixed together for 30 minutes before being injected into the muscle tissue of the mouse. This method is only slightly similar to treating a real snakebite. In the second experiment, the researchers simulated the usual real-world scenario, where antivenom is administered after a snakebite: First, they injected the poison into the muscle tissue of the mouse. Three minutes later, they injected the antibody into the mouse's veins.