Prevention of lethal respiratory vaccinia infections in mice with interferon-α and interferon-γ

The antiviral efficacy of interferons (IFNs) was evaluated using it vaccinia intranasal infection model in mice in this Study. We provide evidence that intranasal administration of IFN-alpha and IFN-gamma (days -1 to +3) resulted in 100 and 90% survival against a lethal respiratory vaccinia infection (8 LD50) in mice, respectively; whereas no animals in the placebo group survived through the study period (21 days). The IFN treatment consisted of a single daily dose of 5 x 10(3) U per mouse for 5 consecutive days. The efficacy of IFN-gamma was evident even when the IFN-gamma treatments started 1-2 days after infection and when a lower dose (2 x 10(3) U per mouse) was used. The treatment of IFN-alpha and IFN-gamma reduced the virus titers in the lungs of infected mice by 1000-10000-fold, when the administration started I day after infection. Our data suggest that IFN-alpha and IFN-gamma are effective in protecting vaccinia-infected mice from viral replication in lungs and mortality, and may be beneficial in other human orthopoxvirus infections. (C) 2003 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.