The search for the gene mutations underlying enterotoxigenic Escherichia coli F4ab/ac susceptibility in pigs: a review

Abstract

Diarrhoea due to enterotoxigenic Escherichia coli with fimbriae F4 (ETEC-F4) is an important problem in neonatal and just weaned piglets and hence for the pig farming industry. There is substantial evidence for a genetic basis for susceptibility to ETEC-F4 since not all piglets suffer from diarrhoea after an ETEC-F4 infection. It is assumed that the wild boar was originally ETEC-F4 resistant and that susceptibility towards ETEC arose after domestication. There are different phenotypes in the pig determined by which of the three existing F4 variants (F4ab, F4ac or F4ad) they are susceptible or resistant for. This suggests that several F4 receptors exist, expressed individually or in combination with each other on the brush border of the piglet’s small intestine. As such, the mucin-type glycoproteins (IMTGP) are described as F4ab/ac receptors, while the intestinal neutral glycospingolipid (IGLad) is proposed as an F4ad receptor. GP74 is a putative F4ab receptor. However, the specific genes that encode for the susceptibility are not yet known. In the past decades, linkage analyses revealed that the loci encoding for the receptor(s) for the two most frequent variants F4ab and F4ac were mapped to the 13th chromosome of the pig (Sus scrofa 13, SSC13). After fine mapping, the region of interest was mapped between two microsatellite markers, Sw207 and S0075, and interesting candidate genes surfaced. Numerous SNP analyses and a few expression studies on the three MUC-genes (MUC4, MUC13 and MUC20) and the transferrin receptor gene (TFRC) as well as on some other positional candidate genes have been performed in order to find the causative mutation for the ETEC-F4ab/ac receptor(s). However, until today, the exact mutation causing susceptibility to ETEC-F4 remains unknown.

Oral Administration of a Select Mixture of Bacillus Probiotics Affects the Gut Microbiota and Goblet Cell Function following Escherichia coli Challenge in Newly Weaned Pigs of Genotype MUC4 That Are Supposed To Be Enterotoxigenic E. coli F4ab/ac Receptor Negative

“…usceptibility to enterotoxigenic Escherichia coli (ETEC) expressing the F4 fimbriae, mainly F4ab and F4ac, is dominantly inherited in neonatal and postweaning piglets (1). ETEC-related postweaning diarrhea (PWD) in piglets is an important cause of economic losses in swine farming (2).…”

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

“…A (Python et al, 2005;Yan et al, 2009;Schroyen et al, 2012). Ren et al (2012) showed evidence that MUC13 is a good candidate for the F4ac receptor.…”

“…The two variants of the fimbriae F18 bind to the same host receptor, whereas the three F4 variants F4ab, F4ac and F4ad each exhibit a specific binding pattern including variation in binding strength (Bijlsma et al, 1982;Billey et al, 1998). The fully adhesive receptor(s) for F4ab and F4ac is/are either controlled by one gene (F4bcR) or by two closely linked genes (Python et al, 2005;Yan et al, 2009;Schroyen et al, 2012).…”

Sequence analysis of Mucin 13 gene region associated with piglet diarrhoea in Indian pigs

“…This fact gives a window to attempt for breeding pigs for resistance towards ETEC mediated diarrhoea using putative candidate genes as markers for indirect selection. However, exact causative mutations responsible for genetic variation in susceptibility to ETEC-F4 are unknown (Schroyen et al, 2012), MUC13 have been proposed to be a putative candidate gene that has been extensively studied for its role in imparting resistance to piglet diarrhoea in piglets. Zhang et al (2008) found out that the MUC13 is in strong linkage disequilibrium with enterotoxigenic E.coli (ETEC) F4ab/ac receptor locus.…”