A vaccine against the Ebola virus has been developed by researchers at the National Institutes for Health in Bethesda, United States. Dr Nancy Sullivan (vaccine research centre) and colleagues used a combination of DNA immunisation and boosting with adenoviral vectors to generate immunity in macaque monkeys. Challenge with a lethal dose of an Ebola virus resulted in uniform infection in controls who died in less than one week. All vaccinated animals were asymptomatic for more than six months, with no detectable virus after the initial challenge. The authors say that using this model may allow the development of a vaccine for humans (Nature 2000;408:605).