[Genetic investigation of the resistance mechanisms of the pig against diarrhea caused by E. coli].

The aim of this study was to determine the position of the receptorgenes coding for the binding places of the K88 E. coli fimbriae, as a first step in the development of a non-invasive diagnostic test to type pigs for sensitivity for or resistance against K88 E.coli neonatal diarrhoea. Two approaches that were subsequently merged were followed. In the first one a linkage study was performed using chromosome 13 microsatellites and the with immunofluorescence determined K88ab, ac and ad phenotypes. Four of the microsatellite markers were found closely associated with the K88ab and ac locus, and these can now be used as a preliminary diagnostic tool to type for K88 resistance or sensitivity. These four markers enclose a 2 Mbp region containing the K88ab and ac receptorgenes. None of the 17 markers showed any linkage with the ad-locus indicating the ad-receptor gene is not located on chromosome 13 of the pig. The second approach was aimed at searching for genes in the chromsome 13 orthologous region of human chromosome 3. The orthologous region could not be determined due to chromosomal rearrangements. However, two chomosomal bands, 3p26 and 3q21, could be found as converging in band 13q31 of the pig, as genes of both human regions were found in the pig in that same location. The genes in these regions can now be used to enrich the map in pig band 13q31 and to search for K88 candidate receptorgenes. Integration of the linkage map with the physical map was performed by FISH mapping some of the microsatellites and by including some of the microsatellites found near the previously FISH mapped genes in the linkage map. In conclusion, one can state that we have now in hand an excellent tool to search for the K88ab and ac receptorgenes in the 2Mbp region flanked by the four microsatellites.