Treatment of Lassa virus infection in outbred guinea pigs with first-in-class human monoclonal antibodies

•125 Lassa glycoprotein-specific huMAbs were assessed for in vitro activity.•Eleven huMAbs were assessed in an outbred guinea pig model of Lassa fever.•Five huMAbs completely protected animals when given shortly after Lassa exposure.

Lassa fever is a significant health threat to West African human populations with hundreds of thousands of annual cases. There are no approved medical countermeasures currently available. Compassionate use of the antiviral drug ribavirin or transfusion of convalescent serum has resulted in mixed success depending on when administered or the donor source, respectively. We previously identified several recombinant human monoclonal antibodies targeting the glycoprotein of Lassa virus with strong neutralization profiles in vitro. Here, we demonstrate remarkable therapeutic efficacy using first-in-class human antibodies in a guinea pig model of Lassa infection thereby presenting a promising treatment alternative.