2 ALPHA(1,2) FUCOSYL-TRANSFERASE GENES ON PORCINE CHROMOSOME-6Q11 ARECLOSELY LINKED TO THE BLOOD-GROUP INHIBITOR (S) AND ESCHERICHIA-COLI F-18 RECEPTOR (ECF18R) LOCI

The Escherichia coli F18 receptor locus (ECF18R) has been genetically mapped to the halothane linkage group on porcine Chromosome (Chr) 6. I n an attempt to obtain candidate genes for this locus, we isolated 5 c osmids containing the alpha(1,2) fucosyltransferase genes FUT1, FUT2, and the pseudogene FUT2P from a porcine genomic library. Mapping by fl uorescence in situ hy bridization placed all these clones in band q11 of porcine Chr 6 (SSC6q11). Sequence analysis of the cosmids resulted in the characterization of an open reading frame (ORF), 1098 bp in len gth, that is 82.3% identical to the human FUT1 sequence: a second ORF, 1023 bp in length, 85% identical to the human FUT?, sequence; and a t hird FUT-like sequence thought to be a pseudogene. The FUT1 and FUT2, loci therefore seem to be the porcine equivalents of the human blood g roup I-I and Secretor loci. Direct sequencing of the two ORFs in swine being either susceptible or resistant to adhesion and colonization by F18 fimbriated Escherichia coli (ECF18) revealed two polymorphisms at bp 307 (M307) and bp 857 (M857) of the FUT1 ORF. Analysis of these mu tations in 34 Swiss Landrace families with 221 progeny showed close li nkage with the locus controlling resistance and susceptibility to E. c oli F18 adhesion and colonization in the small intestine (ECF18R), and with the locus of the blood group inhibitor S. A high linkage disequi librium of M307-ECF18R in Large White pigs makes the M307 mutation a g ood marker for marker-assisted selection of E, coli F18 adhesion-resis tant animals in this breed. Whether the FUT1 or possibly the FUT2 gene products are involved in the synthesis of carbohydrate structures res ponsible for bacterial adhesion remains to be determined.