Efficacy of Favipiravir Alone and in Combination With Ribavirin in a Lethal, Immunocompetent Mouse Model of Lassa Fever

J Infect Dis. 2016 Mar 15;213(6):934-8. doi: 10.1093/infdis/jiv522. Epub 2015 Nov 3.


We studied the therapeutic potential of favipiravir (T-705) for Lassa fever, both alone and in combination with ribavirin. Favipiravir suppressed Lassa virus replication in cell culture by 5 log10 units. In a novel lethal mouse model, it lowered the viremia level and the virus load in organs and normalized levels of cell-damage markers. Treatment with 300 mg/kg per day, commenced 4 days after infection, when the viremia level had reached 4 log10 virus particles/mL, rescued 100% of Lassa virus-infected mice. We found a synergistic interaction between favipiravir and ribavirin in vitro and an increased survival rate and extended survival time when combining suboptimal doses in vivo.

Keywords: Lassa fever; drug interaction; favipiravir; mouse model; ribavirin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amides / administration & dosage
  • Amides / therapeutic use*
  • Animals
  • Antiviral Agents / administration & dosage
  • Antiviral Agents / therapeutic use*
  • Chlorocebus aethiops
  • Drug Therapy, Combination
  • Lassa Fever / drug therapy*
  • Mice
  • Pyrazines / administration & dosage
  • Pyrazines / therapeutic use*
  • Ribavirin / administration & dosage
  • Ribavirin / therapeutic use*
  • Vero Cells
  • Viral Load
  • Virus Replication


  • Amides
  • Antiviral Agents
  • Pyrazines
  • Ribavirin
  • favipiravir