Antibodies made entirely from plastic have saved the lives of mice injected with bee venom – the first time such a strategy has worked in live animals. Researchers developing the antibodies say it is the first step towards customised antibodies for a host of other medical applications, from treating people who have been poisoned to combating infection. Natural antibodies are made by the body's immune system to lock onto a specific "antigen". Likewise, the plastic antibodies contain cavities.