Evaluation of methyl inosine monophosphate (MIMP) and peramivir activities in a murine model of lethal influenza A virus infection

An inbred murine model (BALB/c) was utilized to assess the protective effect of the immunomodulator methyl inosine 5′-monophosphate (MIMP) against infection with influenza A/PR/8/34 (H1N1) virus. Contrary to the data reported for outbred mice (NMRI) infected with the aerosolized virus (Masihi, Hadden, 2003. J. Int. Immunopharmacol. 3, 1205–1215), there were no improvements in the outcomes of infection in the inbred animals treated with MIMP intranasally 1 day before the challenge and/or orally after the challenge for 5 days (up to 10 mg/kg/day). Nevertheless, complete protection against lethality was afforded by the treatment with the neuraminidase inhibitor peramivir given once daily for 5 days after the challenge (10 mg/kg/day). We speculate that the rapid progression of the disease in inbred mice caused by the intranasal challenge may render the MIMP-treatment ineffective. Our results emphasize the need for careful consideration of murine strains and routes of virus challenge in the design of experiments utilizing lethal influenza virus infection.