Protective effect of recombinant murine interferon beta against mouse hepatitis virus infection.

Recombinant murine interferon beta (rMuIFN-beta) protected susceptible C57BL/6 mice against lethal mouse hepatitis virus (MHV) infection. rMuIFN-beta was life saving if it was given intraperitoneally beginning 21 h before infection and daily thereafter for 9 days, and lengthened the survival time if given from 3 h after infection. rMuIFN-beta treatment beginning 24 h after infection was ineffective. The survival rate was dose-dependent, and the 50% effective dose of rMuIFN-beta for survival was 1780 IU per day. rMuIFN-beta pretreatment inhibited virus growth completely in the brain and moderately in the liver and spleen and prevented severe hepatic lesions. rMuIFN-beta also protected beige mice and cyclophosphamide-treated mice against MHV infection, suggesting that activation of natural killer cells or T-cells by rMuIFN-beta is not critical for protection.