Genes specifying receptors for F18 fimbriated Escherichia coli, causing oedema disease and postweaning diarrhoea in pigs, map to chromosome 6.

The study comprised 236 pigs selected for resistance or susceptibility to oedema disease. The susceptibility to colonization of the small intestine by an Escherichia coli strain causing oedema disease was determined: (1) by monitoring faecal excretion of weaned pigs orally inoculated with E. coli strain O139:K12(B):H1:F18ab serotype; and (2) by an in vitro adhesion assay using an F18ab positive E. coli strain and small intestinal enterocyte preparations. Susceptibility to adhesion by these bacteria was shown to be controlled by a dominant (B) allele of the ECF18R locus and resistance by the alternative recessive allele (b). Pigs were typed for 14 blood group systems, 11 biochemical polymorphisms and the polymorphism at nucleotide 1843 of the RYR1 locus. Linkage was demonstrated between the locus for F18 E. coli receptors and the loci S, RYR1, GPI, EAH, A1BG and PGD (Z > 20). The most likely gene orders are: S-ECF18R-RYR1-GPI-PGD or GPI-RYR1-ECF18R-S-PGD. The recombination frequencies between ECF18R-S and ECF18R-RYR1 were estimated to be theta = 0.5% and 3.1%, respectively.