STUDIES IN SWINE ON INHERITANCE AND VARIATION IN EXPRESSION OF SMALL-INTESTINAL RECEPTORS MEDIATING ADHESION OF THE K88 ENTEROPATHOGENIC ESCHERICHIA-COLI VARIANTS

Small intestinal enterocyte preparations from 368 pigs were phenotyped by an in vitro adhesion test using Six strains of K88 Escherichia (E. ) coli, each expressing one of three K88 fimbrial antigenic variants: K88ab, K88ac, or K88ad. All pigs tested were classified into one of fo ur adhesion brush border phenotyes: I (K88ab-, K88ac-, K88ad-); II (K8 8ab-, K88ac+, K88ad+); III(K88ab+, K88ac+, K88ad-); or IV (K88ab+, K88 ac+, K88ad+). The segregation and adhesion affinity data suggest that there are two adhesion affinity receptors for K88ad+ E. coli: a high a ffinity (adh) and a low affinity (adl) receptor. The high affinity rec eptor cosegregates with receptors for K88ab and K88ac fimbrial antigen s forming together the phenotype IV; the low affinity receptor is asso ciated with the adhesion phenotype II, and its physiological expressio n is terminated by 16 weeks of age. In contrast, the K88adH receptor i s expressed during the entire life cycle. The presence of a mixed adhe sion phenotype, K88adM, assumed to be determined by K88ab(-),ac(-),adl (+)/K88ab(+),ac(+),adh(+) heterozygous genotype, is interpreted as an indication that each of the two types of brush border adhesion for the K88ad antigen is expressed on independent enterocytes.