Interferon production and response to exogenous interferon in two cell lines of mouse brain origin persistently infected with Sendai virus

Two persistently infected cell lines established from C3H mouse brain cells infected in vivo with Sendai virus were shown to differ with respect to interferon (IF) production and response to exogenous IF. MB/Sen carrier cells contained 1-5 per cent antigen positive cells when examined by immunofluorescence, and virus was occasionally recovered from the culture medium. MB/Sen_AS carrier cells were maintained with 0.16 per cent Sendai antiserum in the supernatant medium. All MB/Sen_AS cells contained viral antigen and infectious virus was present in the culture medium. MB/Sen released IF spontaneously into the culture medium. Further IF production could be stimulated in MB/Sen by superinfection with Newcastle disease virus (NDV) or vesicular stomatitis virus (VSV). Exogenous IF provided good protection against VSV challenge. In contrast, MB/Sen_AS produced no IF spontaneously but could be stimulated by NDV and VSV to produce IF. Exogenous IF failed to reduce the amount of VSV released into the supernatant fluid. Replication of VSV was restricted in MB/Sen_AS as shown by a 2.3 log₁₀ lower virus yield compared to MB/Sen.