Interferon-alpha protects mice against lethal infection with St Louis encephalitis virus delivered by the aerosol and subcutaneous routes

In common with other flaviviruses, there is no specific therapy for St Loui s encephalitis (SLE) virus infections. A number of cases have occurred wher e infection may have been acquired by the aerosol route in laboratory accid ents. The recombinant human interferon hybrids IFN-alpha A/D (Roche Laborat ories) and IFN-alpha BID (Ciba-Geigy) have activity in murine models. Given for several days around the time of exposure to the virus or shortly after : these compounds reduce the mortality from SLE virus administered to mice subcutaneously by up to 70%. In an aerosol model of SLE disease, the mortal ity was reduced to 30-50% compared to 100% in controls, depending on the ch allenge level of virus. These results suggest that interferon-alpha could b e used to reduce the mortality from SLE infection after known exposure to t he virus. (C) 1999 Elsevier Science B.V. All rights reserved.