Interferon-α/β Genes Are Up-Regulated in Murine Brain Astrocytes After Infection With Theiler’s Murine Encephalomyelitis Virus

This article reports the production of interferon alpha/beta (IFN-alpha/beta) by SJL/J mouse brain astrocyte cultures infected with Theiler's murine encephalomyelitis virus (TMEV). cRNA from mock- and TMEV-infected SJL/J astrocytes was hybridized to the Affymetrix whole murine genome DNA microarray. Analysis revealed the up-regulation of 3 sequences coding for the IFN-alpha/beta domain. Increased expression of mRNA coding for IFN-alpha was shown by conventional RT-PCR and quantitative real-time RT-PCR. According to ELISA, the concentration of IFN-alpha in the supernatants of infected astrocyte cultures varied with the multiplicity of infection and post-infection time. The IFN-alpha/beta secreted was biologically active, as shown by a virus-based IFN bioassay involving Cocal virus and TMEV infection. The contribution to total interferon activity was 29% +/- 3.0% for IFN-alpha and 52% +/- 3.6% for IFN-beta. IFN-alpha/beta was induced by whole TMEV virions; induction was not achieved with either purified isolated virion capsid proteins or UV-inactivated virus. Further, induction was inhibited by specific anti-TMEV antibodies. The receptor for IFN-alpha/beta, which is absent in uninfected astrocytes, was up-regulated after infection, as suggested by DNA hybridization analysis. The brains of infected mice contained IFN-alpha/beta mRNA during the acute encephalitis phase, peaking at day 5 post-infection. Our findings could have significance for human diseases such as viral encephalitis and multiple sclerosis.