Fine‐mapping of the intestinal receptor locus for enterotoxigenic Escherichia coli F4ac on porcine chromosome 13

Abstract

The aim of this study was to refine the localization of the receptor locus for fimbriae F4ac. Small intestinal enterocyte preparations from 187 pigs were phenotyped by an in vitro adhesion test using two strains of Escherichia coli representing the variants F4ab and F4ac. The three-generation pedigree comprised eight founders, 18 F1 and 174 F2 animals, for a total of 200 pigs available for the linkage analysis. Results of the adhesion tests on 171 F2 pigs slaughtered at 8 weeks of age show that 23.5% of the pigs were adhesive for F4ab and non-adhesive for F4ac (phenotype F4abR+/F4acR-; R means receptor). Pigs of this phenotype were characterized by a weak adhesion receptor for F4ab. No pigs were found expressing only F4acR and lacking F4abR. Receptors for F4ab and F4ac (F4abR+/F4acR+) were expressed by 54.5% of the pigs. Animals of this phenotype strongly bound both F4ab and F4ac E. coli. In the segregation study, the serum transferrin (TF) gene and 10 microsatellites on chromosome 13 were linked with F4acR (recombination fractions (theta) between 0.00 and 0.11 and lod score values (Z) between 11.4 and 40.4). The 11-point analysis indicates the F4acR locus was located in the interval S0068-Sw1030 close to S0075 and Sw225, with recombination fractions (theta) of 0.05 between F4acR and S0068, 0.04 with Sw1030, and 0.00 with S0075 and Sw225. The lack of pigs displaying the F4abR-/F4acR+ phenotype and the presence of two phenotypes for F4abR (a strong receptor present in phenotype F4abR+/F4acR+ and a weak receptor in phenotype F4abR+/F4acR-) led us to conclude that the receptor for F4ac binds F4ab bacteria as well, and that it is controlled by one gene localized between S0068 and Sw1030 on chromosome 13.

A refined comparative map between porcine chromosome 13 and human chromosome 3

“…Most prominent amongst these is (are) the gene(s) mediating resistance/susceptibility against K88 (F4) caused neonatal diarrhea, mapped to the middle part of SSC13 (Edfors-Lilja et al, 1995;Python et al, 2002). Apart from this, QTLs for several production traits such as growth rate and body weight (Knott et al, 1998;Wu et al, 2002) have been mapped to this chromosome.…”

Inheritance of porcine receptors for enterotoxigenic Escherichia coli with fimbriae F4ad and their relation to other F4 receptors

“…To test this hypothesis we performed repetitive and targeted matings in which the same pig was mated to different phenotypes (Table 6), for example, sire 2674 was mated to four different resistant dams and sire 2831 was mated to five different dams which were resistant, FA or PA. Dam 2842 was mated to R and FA sires. Although we increased the number of intestinal sites for the adhesion test to four compared with only one site used in previous studies (Python et al, 2002 and2005) it cannot be excluded that we mistyped PA pigs by chance as resistant pigs. A separate χ 2 was calculated in litters with expected FA phenotype to test the two gene inheritance model for the FA receptor.…”

“…The interval between killing and sampling of intestinal tissue was not more than 20 to 40 min to avoid degeneration of the epithelial intestinal cells. The enterocytes were prepared and the MAT performed according to Vögeli et al (1996) and Python et al (2002). Escherichia coli test strains E68I (O 141: K 85ab: F4ab), G4 (O 45: K (E 65): F4ac) and Guinée (O 8: K 87: F4ad) were procured from the Veterinary Laboratory Agency Weybridge, Surrey GB (Thorns et al, 1987).…”

Transmission of F4+ E. coli in groups of early weaned piglets

“…Moreover, selection on F4Rx piglets could have some disadvantages like the change in selection pressure on pathogenic E. coli strains or negative effects on production and welfare as the function of the genes involved are still unknown [21,22]. Furthermore, different serological variants of F4 with different receptors exist.…”