There are no approved or licensed therapeutics for treating henipavirus infection or disease in people, and antiviral approaches against the henipaviruses that have been tested in animal models are few (reviewed in (Broder, 2012)). Ribavirin is a well-known first line treatment strategy for suspected viral infections of unknown etiology. Ribavirin exhibits antiviral activity against a wide variety of both RNA and some DNA viruses (Sidwell et al.,

1972) and is an accepted or approved treatment for several viral infections including respiratory syncytial virus and arenaviral hemorrhagic-fevers (reviewed in (Snell, 2001)). In vitro studies have shown that ribavirin is effective against both Hendra and Nipah virus replication LDN-193189 in vivo ( Aljofan et al., 2009 and Wright PCI-32765 nmr et al., 2005). Also, the anti-malarial drug chloroquine was shown earlier to block the critical proteolytic processing needed for the maturation and function of the Hendra virus F glycoprotein ( Pager et al., 2004), and not surprisingly cholorquine was later

shown to inhibit Nipah and Hendra virus infection in cell culture ( Porotto et al., 2009). An open label ribavirin treatment trial was carried out during the outbreak of Nipah virus in Malaysia in 1998 and was reported to reduce mortality by 36% in treated patients when compared to those patients who presented before ribavirin availability or who refused treatment (Chong et al., 2001). Of the recorded human Hendra virus cases, three individuals were treated with ribavirin, and of these, two succumbed to disease and one survived (Playford

et al., 2010). Chloroquine was administered along with ribavirin to one HeV-infected individual in 2009 (Anonymous, 2009c) with no apparent clinical benefit. Three additional people received ribavirin treatment in combination with chloroquine after suspected exposure to Hendra virus Telomerase contaminated secretions from infected horses. While all three individuals survived, infection was not confirmed and therefore it remains unknown whether the treatment had any effect (Anonymous, 2009a). In the absence of other therapies, ribavirin may be an option for treatment of henipavirus infections. However, more recent animal studies have revealed no therapeutic benefit of either drug. Two studies in hamsters and one study in nonhuman primates (African green monkey (AGM)) showed that ribavirin treatment only delayed but did not prevent death after Nipah or Hendra virus infection (Freiberg et al., 2010, Georges-Courbot et al., 2006 and Rockx et al., 2010) and AGMs treated with ribavirin following Hendra virus infection had marked increases of neurological symptoms. Similarly, chloroquine was unable to prevent Nipah infection or disease in ferrets (Pallister et al., 2009).