The cooperative effect of interferon-alpha and ribavirin on subacute sclerosing panencephalitis (SSPE) virus infections, in vitro and in vivo.

We studied the effects of two antiviral agents, human interferon-alpha (IFN-alpha) and ribavirin, on subacute sclerosing panencephalitis (SSPE) virus infections in hamsters. By intracranial administration, IFN-alpha alone improved the survival of infected hamsters by 20% at a dose of 6 x 10(4) IU/kg every other day for 10 days. When the dose of IFN-alpha was increased incrementally to 6 x 10(6) IU/kg, the survival rate increased by 70% in a dose-dependent manner. The combination of IFN-alpha and ribavirin had a synergic inhibitory effect on the replication of SSPE virus in cell culture. Combination of IFN-alpha (at a dose of 6 x 10(5) IU/kg) with ribavirin (at a dose of 1 mg/kg) completely prevented mortality. This was significantly better than either IFN-alpha or ribavirin monotherapy (p < 0.05). Under the conditions used, IFN-alpha did not enhance the toxicity of ribavirin in hamsters. Intraventricular administration of high dose IFN-alpha and ribavirin may have potential usefulness in the treatment of patients with SSPE.