Interferon and humoral immune response in experimental influenza: infection with A/PR8 virus adapted to the mouse.

Inbred 129/Ao/Boy mice were infected with various doses of AO/PR8/HONI influenza virus. Replication of virus, synthesis of endogenous interferon and antibodies were measured. The infected mice were the source of alveolar and peritoneal cells which were used for the in vitro induction of interferon with Newcastle Disease virus (NDV). It has been found that the level of interferon detected in the tracheo-bronchial washings parallels the titer of virus in the lung. At the lethal doses of the virus interferon appeared earlier but its titer also declined faster than in mice infected with sublethal doses of influenza virus. The peritoneal and alveolar cells from the mice infected with the lethal doses of influenza virus produced less interferon after the induction with NDV than the cells from uninfected mice. In contrast, the alveolar cells from mice infected with sublethal doses of A/PR8 virus produced more interferon than the control cells.