The mechanism of protection of infant mice from intestinal colonisation with Campylobacter jejuni.

BALB/c mice, vaccinated intraperitoneally with a heat-killed (62 degrees C) suspension of Campylobacter jejuni before mating, completely protect c. 90% of their own infants from intestinal colonisation. This protection has now been investigated further in fostering experiments. Fostering by vaccinated dams within the first 24 h of life prevented intestinal colonisation in 50% of infants from non-vaccinated dams, and reduced colonisation in a further 25%. Infants from vaccinated dams, even if allowed to receive their own mothers' colostrum and milk, became susceptible to challenge when subsequently fostered by non-vaccinated dams. Immunity in experimentally infected infant mice depended upon the consumption of immune milk at and after the time of challenge. High concentrations of IgG antibodies specific for C. jejuni were found in the serum and mammary secretion of vaccinated dams, but there was very little specific IgA antibody.