Protective Role of Human Intravenous Immunoglobulin from Influenza AVirus Infection in Mice

Intravenous immunoglobulin (IVIG) has been manufactured from pooled plasma of 10,000 or more units from healthy donors. Recently, we reported that the IVIG manufactured even before the 2009 influenza pandemic contained antibodies reactive to seasonal H1N1 and pandemic H1N1 2009 (H1N1 pdm) viruses. In this study, we used an animal model to evaluate the efficacy of IVIG against influenza infections. A seasonal influenza H1N1 strain (New Caledonia, A/NC/20/99) and an H1N1 pdm strain (A/Osaka/168/2009) were used. The BALB/c and severe combined immuno- deficiency mice (SCID; C.B-17/lcr-scid/scid) were also used. Mice inoculated with A/NC/20/99 or A/Osaka/168/2009 were administrated IVIG and monitored for 3 weeks. The administration of IVIG 48 h before and after inoculation with a mouse-adapted seasonal H1N1 virus, resulted in survival rates of 80 and 88%, respectively. The rate among control mice was 30%. In addition, infectivity in lungs from IVIG-treated mice also decreased significantly. Similar effects of IVIG on the survival rate were obtained with H1N1 pdm. Thus, IVIG was shown to be effective against both viruses in mice.