Ebola and Marburg vaccines for Africa: one step closer

Filovirus vaccines have been in development since the late 1990s.3 Gene-based vaccination strategies in which virus surface glycoprotein is presented in a DNA plasmid or viral vectors are the most advanced vaccine candidates, having shown 100% protective efficacy in non-human primates.3 The Vaccine Research Center at the US National Institutes of Health (Bethesda, MD, USA) developed DNA vaccines encoding different versions of the Ebola virus and Marburg virus glycoproteins, which were safe and immunogenic in phase 1 clinical trials in healthy adults in the USA.4,5 The data generated from clinical trials of these DNA vaccines, along with preclinical data for their efficacy, informed the choice of the antigenic construct used in the Ebola virus vaccine based on a chimpanzee adenovirus vaccine vector (cAd3) currently being assessed in phase 1 trials in the USA, UK, Mali, and Uganda in response to the ongoing Ebola virus outbreak in west Africa.6 However, as with many vaccines developed elsewhere, a crucial question that remains is whether they are safe and equally immunogenic when used in Africa.