Figure 2. Histologic and in situ hybridization analyses of livers from cynomolgus macaques infected with Lassa virus (LASV) (1 × 104 50% tissue culture infective dose [TCID50]) and treated 1 time daily with favipiravir (treated) or vehicle only (control). A–B) Histologic analyses. A) Control, showing multifocal neutrophilic infiltrates with hepatocyte necrosis and degeneration (original magnification ×40). Inset shows hepatocyte necrosis (original magnification ×400). B) Treated, showing essentially healthy hepatic tissue (original magnification ×40). Inset shows healthy hepatic tissue (original magnification ×400). C–D) In situ hybridization analyses. C) Control, showing multifocal and coalescing viral RNA detected within hepatocytes (original magnification ×100). D) Treated, showing no viral RNA detected (original magnification ×100).