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

Abstract

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 (F4adR FA ) expressed on all enterocytes and at all small intestinal sites, and a partially adhesive receptor (F4adR PA ) variably expressed at different sites and often leading to partial bacterial adhesion. In pigs with both F4ad receptors, the F4adR PA receptor is masked by the F4adR FA . The hypothesis that F4adR FA must be encoded by at least two complementary or epistatic dominant genes is supported by the Hardy-Weinberg equilibrium statistics. The F4adR PA receptor is inherited as a monogenetic dominant trait. A comparable partially adhesive receptor for variant F4ab (F4abR PA ) 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 (F4abR FA /F4acR + /F4adR FA ); A2 (F4abR FA /F4acR + /F4adR PA ); B (F4abR FA /F4acR + / F4adR − ); C1 (F4abR PA /F4acR − /F4adR FA ); C2 (F4abR PA /F4acR − /F4adR PA ); D1 (F4abR − /F4acR − /F4adR FA ); D2 (F4abR − /F4acR − / F4adR PA ); E (F4abR − /F4acR − /F4adR − ).

Animal EnterotoxigenicEscherichia coli

“…Some of the additional mucin receptors might represent released degradation products of larger brush border receptors. Depending on the presence or absence of the different F4 receptors, up to 8 groups of receptor phenotypes were described (157), with six having been studied in more details (158)(Table 5). As shown with different glycoconjugate receptors, the three F4 variants demonstrate lectin activities specific for a minimal recognition sequence containing a ß-linked HexNAc, a terminal ß-linked galactose enhancing the binding (159).…”

Comparative jejunal expression of MUC 13 in Indian native pigs differentially adhesive to diarrhoeagenic E. coli

“…However, Goetstouwers et al (2014) rejected that hypothesis. Rampoldi et al (2014) examined four different small intestinal sites instead of one for adhesion of the fimbrial variants but did not find any relations to the strong receptors for variants F4ab and F4ac. Previous studies on RT-PCR analysis reported that the porcine MUC13 mRNA expression was markedly different in diverse tissues, with the highest level in the jejunum; moderate levels in the trachea, stomach and liver; and low levels (or no expression) in the other 14 tissues (Zhang et al 2008).…”

Effective genetic markers for identifying the Escherichia coli F4ac receptor status of pigs

“…Targeted mating allowed for the discrimination between fully adhesive receptors (F4abR FA and F4adR FA ), expressed on all enterocytes and at all sites in the small intestine, and partially adhesive receptors (F4abR PA and F4adR PA ), variably expressed at different sites, often leading to partial bacterial adhesion (Rampoldi et al . ). These observations led to three additional receptor phenotypes: A2 (F4abR FA /F4acR + /F4adR PA ), C2 (F4abR PA /F4acR − /F4adR PA ) and D2 (F4abR − /F4acR − /F4adR PA ).…”

“…The genes encoding the F4 receptors have not yet been identified (Rampoldi et al . , ). Three antigenic variants of F4 have been described: F4ab, F4ac and F4ad (Guinee & Jansen ).…”

“…Rampoldi et al . () proposed that the fully expressed F4adR FA phenotype is controlled by two genes that have an epistatic component, whereas the partially expressed F4adR PA phenotype is controlled by a dominant gene.…”