Intracellular stability of the interfering activity of a defective interfering influenza virus in the absence of virus multiplication.

Half-lives of the interfering activity of a human defective interfering (DI) influenza virus and of viral RNA in MDCK cells inoculated with noninfectious DI virus were 25 and 17 days, respectively, and of viral RNA in cells inoculated with noninfectious uv-irradiated standard virus was 21 days. In neither case was there evidence of virus replication (de novo synthesis of viral proteins, haemagglutinin, or infectivity). The half-life in BHK cells was shorter, although still considerable, showing evidence of a host contribution to stability. Implications of the putative persistence of influenza virus genes in vivo to the natural history of the virus are discussed.