Effect of poly I: C on experimental respiratory infection in hamsters.

The interferon inducer double-stranded polyinosinic acid and polycytidylic acid (poly I:C) was studied in hamsters experimentally infected with parainfluenza 3 virus. Upper intranasal, deep intranasal, or intraperitoneal treatment of hamsters with poly I:C (100 mug/100- to 120-g animal) 24 hr before an upper respiratory infection significantly reduced the virus yields taken 28 hr after infection. Deep intranasal and intraperitoneal treatment with poly I:C greatly decreased the virus titers in the lungs, as measured 48 hr after a deep lung infection with parainfluenza 3 virus; however, the upper respiratory poly I:C treatment was ineffective.