ABSTRACT
INTRODUCTION A 2004 review of viral hemorrhagic fevers by Geisbert and Jahrling considered a Lassa vaccine to be ‘‘low-hanging fruit,’’ meaning that it should be an easily attainable goal for vaccinologists (1). They assessed the promising vaccine candidates at that time. Groups in the United States and the United Kingdom had already showed that vaccines could protect guinea pigs if they expressed either the nucleocapsid protein (NP) or the envelope glycoprotein of the Lassa virus. The nonhuman primate model was more discriminating than the guinea pig model, but it too could be protected by a vector that only expressed the envelope glycoprotein of Lassa virus.
