Prenatal immunization against experimental enteric colibacillosis in piglets.

To establish a model for the study of prenatal immunization against enteric colibacillosis a proportion of the litters of seven sows were immunized in utero 18 to 22 days before term by intra-amniotic and intramuscular injection of Escherichia coli antigen and the litters challenged at birth with either homologous or heterologous strains. Protection against homologous challenge was demonstrated in some but not all vaccinated piglets. The study was severely compromised by the occurrence of intrauterine death in a significant proportion of vaccinated piglets.