title: Detection of a quantitative trait locus associated with resistance to Ascaris suum infection in pigs.
abstract: Helminths almost invariably have an over-dispersed distribution in the host population. Human and animal studies have provided evidence suggesting that a large part of this variation is due to host genetic factors. Recently, the heritability for roundworm (Ascaris suum) infection levels in pigs was estimated to be 0.45. We used single nucleotide polymorphism markers to perform a whole-genome scan on 195 pigs experimentally infected with A. suum. A putative quantitative trait locus for worm burden on chromosome 4 covering 2.5 Mbp was identified by measured genotype analysis, although none of the SNPs reached genome-wide significance. To validate the putative quantitative trait locus, we genotyped two of the SNPs within the region in unrelated, informative animals exposed to experimental or natural infections and from which we had worm counts and/or faecal egg counts; the validation studies showed that one of the SNPs (TXNIP) was associated with total worm burden (P < 0.001) and adult worm burden(P < 0.0001), whereas the other SNP (ARNT) was associated with adult worm burden (P < 0.025) in these populations. We were thus able to confirm the existence of the quantitative trait locus on chromosome 4.This is to our knowledge the first report of a quantitative trait locus associated with helminth burden in pigs.
authors.affiliation: Parasitology, Health, and Development, Department of Veterinary Disease Biology, University of Copenhagen, Dyrlægevej 100, DK-1870 Frederiksberg, Denmark. pesk@life.ku.dk
authors.forename: Per
authors.initials: P
authors.lastname: Skallerup
authors.forename: Peter
authors.initials: P
authors.lastname: Nejsum
authors.forename: Claus B
authors.initials: CB
authors.lastname: Jørgensen
authors.forename: Harald H H
authors.initials: HH
authors.lastname: Göring
authors.forename: Peter
authors.initials: P
authors.lastname: Karlskov-Mortensen
authors.forename: Alan L
authors.initials: AL
authors.lastname: Archibald
authors.forename: Merete
authors.initials: M
authors.lastname: Fredholm
authors.forename: Stig M
authors.initials: SM
authors.lastname: Thamsborg
mesh_terms: D000818:Animals; D001196:Ascariasis / Q000235:genetics / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D017165:Ascaris suum / Q000276:immunology* / Q000302:isolation & purification; D033481:Chromosomes, Mammalian; D060467:Disease Resistance; D005260:Female; D005787:Gene Frequency; D016678:Genome; D005838:Genotype; D008297:Male; D059208:Parasite Load; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D013552:Swine; D013553:Swine Diseases / Q000235:genetics* / Q000276:immunology* / Q000469:parasitology