K88 variants K88ab, K88ac and K88ad in oral vaccination of different porcine adhesive phenotypes. Immunological aspects.

Sows of different adhesive phenotypes were vaccinated orally during the last 4 weeks of gestation with K88-positive Escherichia coli. Sows susceptible to adhesion by the K88 variant of the vaccination strain produced a significant IgA-class specific anti-K88 response in colostrum and milk and post-farrowing serum. Indications for an IgM and IgG-class specific anti-K88 response were also found in this group but only in milk. In sows resistant to adhesion by the K88 variant of the vaccination strain only an IgA-class specific anti-K88 antibody response was found in mammary secretions and in post-farrowing sera, but titres did not reach the high values of the former group. The response in the second group was attributed to the frequent administration of large quantities of K88-positive E. coli which to some extent can be compared with a colonization effect. Specificity for the serological components of the K88 variants was detectable in colostral IgA of sows susceptible to the vaccination strain only.