The F4ac receptor locus (F4acR), which encodes susceptibility or resistance to Escherichia coli diarrhoea, is inherited as an autosomal recessive monogenetic trait. F4acR is localized on pig chromosome 13 (SSC13q41-q44) near the MUC13 gene. Two flanking markers (CHCF1 and ALGA0106330) with a high linkage disequilibrium (LD) with F4acR were found to be effective for the genetic identification of F4ac-resistant pigs in the Swiss Large White breed (one recombinant out of 2034 genotyped pigs). Three recombinant boars, one each from the Duroc, Swiss Landrace and Piétrain breeds, were genotyped with seven different markers and phenotyped by means of a microscopic adhesion test. Only ALGA0072075, CHCF1 and CHCF3 indicated the correct phenotype. To test the effect of the resistance allele on production traits, 530 Large White pigs from the national test station were investigated. A significant difference existed among the F4acR locus genotypes in the intramuscular fat content of the longissimus dorsi muscle, whereas no other production traits were influenced by the resistance allele. The frequency of the CHCF1-C and ALGA0106330-A alleles associated with resistance in the Swiss Large White population was 60%, which is advantageous for implementing this trait in a breeding programme to select for E. coli F4ac-resistant animals. The selection of resistant pigs should start on the male side due to the inability of resistant sows to produce sufficient amounts of protecting antibodies in the colostrum. Selection of genetically F4ac-resistant pigs is a sustainable and suitable alternative to decreasing animal loss and antibiotic use due to diarrhoea.

Single-locus disorders in domesticated animals were among the first Mendelian traits to be documented, and to be included in early linkage maps. The use of linkage maps and comparative genomics has been essential to the identification of the causative genes for disorders. A DNA marker for selection of resistance to F18+ E. coli in the pig is available since several years. The use of this marker decreases mortality due to post-weaning diarrhoea and/or oedema disease. For more than 100 disorders the molecular lesion has been identified and hence for which a DNA test is available. However, for most diseases such as Porcine Reproductive and Respiratory Syndrome (PRRS) and Porcine Circovirus Associated Diseases (PCVAD), resistance is a complex and polygenic trait. Novel technologies such as gene microarrays and advanced bioinformatics are being used to analyse health data. Lagging behind, however, is availability of large DNA data sets from pedigreed populations with accurately measured health phenotypes that are needed to identify associations between markers and health traits. As the pig genome is sequenced to a great extent and ten thousands of markers can be analysed at a reasonable price, genomic selection for health traits is possible. Ein-Locus-Erbkrankheiten bei Nutztieren gehören zu den ersten nach Mendel vererbten Merkmalen, die bereits in früheren Genkarten dokumentiert sind. Der Gebrauch von Gen- und Kopplungskarten und der vergleichenden Genomik zwischen Spezies ist zentral für die Identifikation von ursächlichen Genen für Krankheiten. Ein DNS-Marker für Selektion auf Resistenz gegen F18+ E. coli beim Schwein ist seit Jahren verfügbar. Die Anwendung dieses Markers in der Zucht führt zu verminderten Verlusten als Folgen von Absetzdurchfall und/oder Ödemkrankheit. Bei hunderten von Erbkrankheiten bei Nutztieren ist die molekulare Ursache bekannt. Für die meisten Krankheiten wie beispielsweise das Porcine Reproductive and Respiratory Syndrom (PRRS) und das Postweaning Multisystemic Wasting Syndrom (PMWS) ist die Resistenz komplex und ein polygenes Merkmal. Neue Technologien wie Microarray-Chips und moderne Bioinformatik werden für die Analyse von Gesundheitsdaten verwendet. Leider verfügen wir über keine grossen DNS-Datensätze von Familien mit präzis bestimmten Gesundheitsmerkmalen, um Beziehungen zwischen Markern und Gesundheitseigenschaften zu bestimmen. Da das Genom des Schweines grösstenteils sequenziert ist und zehntausende von Markern kostengünstig bestimmt werden können, ist die genomische Selektion für Gesundheitsmerkmale möglich.Les maladies monogéniques des animaux domestiques furent parmi les premières pathologiques génétiques mendéliennes documentées et répertoriées dans les premiers arbres génétiques. L'utilisation des arbres génétiques et de la comparaison génomique eut un rôle essentielle pour démontrer l'origine génétique de ces pathologies. Un marqueur ADN permettant la sélection de porcs résistant au E. coli F18+ est disponible depuis plusieurs années. L'utilisation de ce marqueur décroit la mortalité causée par la diarrhée post sevrage et/ou l'œdème. Pour plus de 100 pathologies, une anomalie génétique a été identifiée et un test ADN est disponible. Par contre, pour de nombreuses pathologies comme le syndrome respiratoire et de reproduction porcine (SRRP) et les maladies associées au circovirus porcin (MACVP), la résistance est un caractère complexe et polygénique. De nouvelles technologies comme les puces à ADN et la bio-informatique de pointe sont actuellement utilisées pour analyser ces données concernant la santé des animaux. Toutefois, il existe un grand retard concernant l'accessibilité de grandes quantités de données provenant d'animaux parfaitement typés sur des critères phénotypiques associés à la santé et qui sont indispensable pour identifier les liens entre les marqueurs ADN et santé. Comme le génome porcin est entièrement séquencé et que plus de10'000 marqueurs ADN peuvent être analysés pour un prix raisonnable, la sélection génétique sur la base de caractères modulant la santé des animaux est possible.Negli animali domestici i disordini del singolo locus sono stati tra i primi tratti mendeliani ad essere documentati ed essere inclusi nelle prime mappe di linkage. L'uso di mappe di linkage e di genomica comparativa sono stati essenziali per l'identificazione dei geni responsabili di malattie. Un marcatore di DNA per la selezione alla resistenza a F18+ E. coli nei suini è disponibile da diversi anni. L'uso di questo marcatore riduce la mortalità dovuta della diarrea post-svezzamento e/o l'edema. Per più di 100 disturbi è stata identificata la lesione molecolare, per la quale è disponibile un test del DNA. Tuttavia, per la maggior parte delle malattie come la sindrome riproduttiva e respiratoria dei suini (PRRS) e le malattie associata al circovirus suino (PCVAD), la resistenza è dovuta a un complesso tratto poligenico. Le nuove tecnologie, come gene microarray e la bioinformatica avanzata vengono utilizzati per analizzare i dati sanitari. Non tiene il passo, comunque, la disponibilità di grandi DNA dataset da popolazioni selezionate con fenotipi misurati con precisione, che sono necessari per identificare le associazioni tra i marcatori e i caratteri. Poiché il genoma del maiale sta venendo attivamente sequenziato e decine di migliaia di marcatori possono essere analizzati ad un prezzo ragionevole, la selezione genomica per caratteri è possibile.

Enteric Escherichia coli infections are a highly relevant cause of disease and death in young pigs. Breeding genetically resistant pigs is an economical and sustainable method of prevention. Resistant pigs are protected against colonization of the intestine through the absence of receptors for the bacterial fimbriae, which mediate adhesion to the intestinal surface. The present work aimed at elucidation of the mode of inheritance of the F4ad receptor which according to former investigations appeared quite confusing. Intestines of 489 pigs of an experimental herd were examined by a microscopic adhesion test modified in such a manner that four small intestinal sites instead of one were tested for adhesion of the fimbrial variant F4ad. Segregation analysis revealed that the mixed inheritance model explained our data best. The heritability of the F4ad phenotype was estimated to be 0.7±0.1. There are no relations to the strong receptors for variants F4ab and F4ac. Targeted matings allowed the discrimination between two F4ad receptors, that is, a fully adhesive receptor (F4adRFA) expressed on all enterocytes and at all small intestinal sites, and a partially adhesive receptor (F4adRPA) variably expressed at different sites and often leading to partial bacterial adhesion. In pigs with both F4ad receptors, the F4adRPA receptor is masked by the F4adRFA. The hypothesis that F4adRFA must be encoded by at least two complementary or epistatic dominant genes is supported by the Hardy–Weinberg equilibrium statistics. The F4adRPA receptor is inherited as a monogenetic dominant trait. A comparable partially adhesive receptor for variant F4ab (F4abRPA) was also observed but the limited data did not allow a prediction of the mode of inheritance. Pigs were therefore classified into one of eight receptor phenotypes: A1 (F4abRFA/F4acR+/F4adRFA); A2 (F4abRFA/F4acR+/F4adRPA); B (F4abRFA/F4acR+/F4adR−); C1 (F4abRPA/F4acR−/F4adRFA); C2 (F4abRPA/F4acR−/F4adRPA); D1 (F4abR−/F4acR−/F4adRFA); D2 (F4abR−/F4acR−/F4adRPA); E (F4abR−/F4acR−/F4adR−).

Single-locus disorders in domesticated animals were among the first Mendelian traits to be documented, and to be included in early linkage maps. The use of linkage maps and comparative genomics has been essential to the identification of the causative genes for disorders. A DNA marker for selection of resistance to F18+ E. coli in the pig is available since several years. The use of this marker decreases mortality due to post-weaning diarrhoea and/or oedema disease. For more than 100 disorders the molecular lesion has been identified and hence for which a DNA test is available. However, for most diseases such as Porcine Reproductive and Respiratory Syndrome (PRRS) and Porcine Circovirus Associated Diseases (PCVAD), resistance is a complex and polygenic trait. Novel technologies such as gene microarrays and advanced bioinformatics are being used to analyse health data. Lagging behind, however, is availability of large DNA data sets from pedigreed populations with accurately measured health phenotypes that are needed to identify associations between markers and health traits. As the pig genome is sequenced to a great extent and ten thousands of markers can be analysed at a reasonable price, genomic selection for health traits is possible.

Diarrhoea in newborn and weaned pigs caused by enterotoxigenic Escherichia coli (ETEC) expressing F4 fimbriae leads to considerable losses in pig production. In this study, we refined the mapping of the receptor locus for ETEC F4ab/F4ac adhesion (F4bcR) by joint analysis of Nordic and Swiss data. A total of 236 pigs from a Nordic experimental herd, 331 pigs from a Swiss experimental herd and 143 pigs from the Swiss performing station were used for linkage analysis. Genotyping data of six known microsatellite markers, two newly developed markers (MUC4gt and HSA125gt) and an intronic SNP in MUC4 (MUC4-8227) were used to create the linkage map. The region for F4bcR was refined to the interval SW207-S0075 on pig chromosome 13. The most probable position of F4bcR was in the SW207-MUC4 region. The order of six markers was supported by physical mapping on the BAC fingerprint contig from the Wellcome Trust Sanger Institute. Thus, the region for F4bcR could be reduced from 26 to 14 Mb.

The OK antigens and the fimbriae F4 of E. coli with haemolysis isolated from 113 cases of oedema disease and/or diarrhoea were identified serologically. The genes for F18 and for enterotoxins LT, STIa and STII as well as Shigatoxin Stx2e were determined by PCR. Fimbrial variants F18ab and F18ac were distinguished by means of indirect immunofluorescence on smears prepared from the intestinal mucosa and from cultures grown under appropriate conditions. Adhesive fimbriae were detected with every case or isolate, respectively, by means of at least one out of the techniques mentioned above. The serogroup O149:K91 with fimbriae F4ac (K88ac) and genes for the enterotoxins LT and STII was most prevalent. Serogroup O139:K12 with fimbriae F18ab and the gene for Stx2e was second, whereas serogroups O141ab and O141ac with fimbriae F18ac and genes for Stx2e, STII and often LT were much less prevalent. The serogroup O147:K89 with fimbriae F18ac, and genes for STIa and STII was detected for the first time in Switzerland.

The OK antigens and the fimbriae F4 of E. coli with haemolysis isolated from 113 cases of oedema disease and/or diarrhoea were identified serologically. The genes for F18 and for enterotoxins LT, STIa and STII as well as Shigatoxin Stx2e were determined by PCR. Fimbrial variants F18ab and F18ac were distinguished by means of indirect immunofluorescence on smears prepared from the intestinal mucosa and from cultures grown under appropriate conditions. Adhesive fimbriae were detected with every case or isolate, respectively, by means of at least one out of the techniques mentioned above. The serogroup O149:K91 with fimbriae F4ac (K88ac) and genes for the enterotoxins LT and STII was most prevalent. Serogroup O139:K12 with fimbriae F18ab and the gene for Stx2e was second, whereas serogroups O141ab and O141ac with fimbriae F18ac and genes for Stx2e, STII and often LT were much less prevalent. The serogroup O147:K89 with fimbriae F18ac, and genes for STIa and STII was detected for the first time in Switzerland.

Oedema disease and post-weaning diarrhoea in swine are associated with the colonization of the intestine with toxigenic Escherichia (E.) coli bacteria of various serotypes. Colonization depends on specific binding between adhesive fimbriae and receptors on the enterocytes. The demonstration of these receptors allows the identification of susceptible and resistant pigs. Direct sequencing of the alpha (1,2) fucosyltransferase gene (FUT1) in swine being either susceptible or resistant to adhesion by F18 fimbriated E.coli revealed a mutation at basepair 307 (M307). Analysis of the mutation in Swiss Landrace and Large White families showed close linkage with the locus controlling resistance and susceptibility to E.coli F18 adhesion (ECF18R). The FUT1 (M307) mutation is a good marker for selection of E.coli of F18 adhesion resistant animals. The mutation is found with variable frequencies in Duroc, Hampshire and Pietrain pigs as well.

The Escherichia coli F18 receptor locus (ECF18R) has been genetically mapped to the halothane linkage group on porcine Chromosome (Chr) 6. In an attempt to obtain candidate genes for this locus, we isolated 5 cosmids containing the α(1,2)fucosyltransferase genes FUT1, FUT2, and the pseudogene FUT2P from a porcine genomic library. Mapping by fluorescence in situ hybridization 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 length, that is 82.3% identical to the human FUT1 sequence; a second ORF, 1023 bp in length, 85% identical to the human FUT2 sequence; and a third FUT-like sequence thought to be a pseudogene. The FUT1 and FUT2 loci therefore seem to be the porcine equivalents of the human blood group H 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 mutations in 34 Swiss Landrace families with 221 progeny showed close linkage with the locus controlling resistance and susceptibility to E. coli F18 adhesion and colonization in the small intestine (ECF18R), and with the locus of the blood group inhibitor S. A high linkage disequilibrium of M307–ECF18R in Large White pigs makes the M307 mutation a good marker for marker-assisted selection of E. coli F18 adhesion-resistant animals in this breed. Whether the FUT1 or possibly the FUT2 gene products are involved in the synthesis of carbohydrate structures responsible for bacterial adhesion remains to be determined.

Postmortem investigation was performed on 54 scouring (soon after onset of diarrhea) and 23 healthy suckling piglets. The animals were 1 to 4 weeks of age and were collected from 27 herds. In 21 herds diarrhea had been observed for a long time in piglets in this age group. Coccidia were found in 34 piglets, rotavirus in 2, cryptosporidia in 2, enterotoxigenic E. coli in 6, attaching and effacing E. coli in 1, Cl. perfringens type C in 1, Campylobacter coli in 53 and C. hyointestinalis in 8 piglets. Some of these microorganisms were isolated from healthy piglets as well. TGE- and PED-Virus antigen, as well as Salmonella were not recovered from any of the pigs. Results of the histopathological and enzyme histochemical investigations were in agreement with data from the literature. They confirmed and emphasized the role of coccidia as enteropathogenic agents in the animals examined. On the other hand evidence was shown, that C. coli is non-pathogenic. The role of C. hyointestinalis could not be fully elucidated. At least one sort of enteropathogenic agent was detected in about 68% (n = 37) of the scouring pigs or was present in 81% (n = 17) of the herds, respectively.