Over the past few years great efforts have been made to find potential therapeutic and vaccination approaches in the arenavirus field (reviewed in [3, 4, 5] ). Until now there is no specific and effective treatment available to combat hemorrhagic fevers caused by arenaviruses. Administration of convalescent plasma has been reported to reduce the mortality rates of patients with Argentine hemorrhagic fever, however, 10% of immune-plasma recipients developed a late neurological syndrome of unknown origin [6] . The only existing drug used to treat Lassa fever and certain South American hemorrhagic fevers is the broad-spectrum antiviral agent ribavirin, a ribonucleoside analogue, which has shown to be partially effective if given early in the course of illness [7, 8, 9, 10] . Even though the drug is relatively inexpensive for patients in highdeveloped countries, it is still unaffordable for many of those living in West Africa and South America. Moreover, several adverse effects have been associated with ribavirin therapy in patient studies and animal models [11, 12, 13, 14, 15] . The lack of effective disease control measures as well as the discovery of new fatal arenavirus species that pose a risk of epidemic potential [16, 17] , emphasize the need for novel therapeutic interventions.