GENES SPECIFYING RECEPTORS FOR F-18 FIMBRIATED ESCHERICHIA-COLI, CAUSING EDEMA DISEASE AND POSTWEANING DIARRHEA 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 in testine by an Escherichia coli strain causing oedema disease was deter mined: (1) by monitoring faecal excretion of weaned pigs orally inocul ated with E. coli strain O139:K12(B):H1:F18ab serotype; and (2) by an in vitro adhesion assay using an F18ab positive E. coil strain and sma ll intestinal enterocyte preparations. Susceptibility to adhesion by t hese bacteria was shown to be controlled by a dominant (B) allele of t he ECF18R locus and resistance by the alternative recessive allele (b) . Pigs were typed for 14 blood group systems, 11 biochemical polymorph isms and the polymorphism at nucleotide 1843 of the RYR1 locus. Linkag e was demonstrated between the locus for F18 E. coli receptors and the loci S, RYR1, GPI, EAH, A1BG and PGD ((Z) over cap > 20), The most li kely gene orders are: S-ECF18R-RYR1-GPI-PGD or GPI-RYR1-ECF18R-S-PGD. The recombination frequencies between ECF18R-S and ECF18R-RYR1 were es timated to be <(theta)over cap> = 0 . 5% and 3 . 1%, respectively.