Initial approaches using inactivated virus to develop a vaccine against MARV were unsuccessful or had contradictory results [16] . In addition, successful protection of rodents did not always translate into protection of NHPs. For example, inactivated MARV protects guinea pigs from lethal MARV challenge but only 50% of challenged NHPs survived [210, [242] [243] [244] . A panel of different approaches has been used in order to develop successful vaccines for MARV (reviewed in [245, 246] ).