Maternally derived immune resistance to fatal diarrhea in infant mice due to mouse hepatitis virus.

Adult female ICR mice were able to produce high titered neutralizing antibodies to mouse hepatitis virus (MHV) by repeated intraperitoneal injections of formalin-inactivated virus. Offspring sucklings born to the immunized dams resisted to MHV causing fatal diarrhea, when their dams had a complement fixing antibody titer of 1:5 or higher. The protection was found to be mediated mainly through neutralizing IgG antibodies in the milk. Sucklings from non-immune dams were also protected by foster-nursing by immune mothers.