title: A genome scan for QTL affecting resistance to Haemonchus contortus in sheep.
abstract: Gastrointestinal nematodes are one of the main health issues in sheep breeding. To identify loci affecting the resistance to Haemonchus contortus, a genome scan was carried out using 1,275 Romane × Martinik Black Belly backcross lambs. The entire population was challenged with Haemonchus contortus in 2 consecutive experimental infections, and fecal egg counts (FEC) and packed cell volumes were measured. A subgroup of 332 lambs with extreme FEC was necropsied to determine the total worm burden, length of female worms, sex ratio in the worm population, abomasal pH, and serum and mucosal G immunoglobulins (IgG) responses. Pepsinogen concentration was measured in another subset of 229 lambs. For QTL detection, 160 microsatellite markers were used as well as the Illumina OvineSNP50 BeadChip that provided 42,469 SNP markers after quality control. Linkage, association, and joint linkage and association analyses were performed with the QTLMAP software. Linkage disequilibrium (LD) was estimated within each pure breed, and association analyses were carried out either considering or not the breed origin of the haplotypes. Four QTL regions on sheep chromosomes (OAR)5, 12, 13, and 21 were identified as key players among many other QTL with small to moderate effects. A QTL on OAR21 affecting pepsinogen concentration exactly matched the pepsinogen (PGA5) locus. A 10-Mbp region affecting FEC after the 1st and 2nd infections was found on OAR12. The SNP markers outperformed microsatellites in the linkage analysis. Taking advantage of the LD helped to refine the locations of the QTL mapped on OAR5 and 13.
authors: INRA, UR631, Station d'Amélioration Génétique des Animaux, BP 27, F-31326, Castanet-Tolosan, France. Guillaume.Salle@tours.inra.fr
authors: G
authors: G
authors: Sallé
authors: P
authors: P
authors: Jacquiet
authors: L
authors: L
authors: Gruner
authors: J
authors: J
authors: Cortet
authors: C
authors: C
authors: Sauvé
authors: F
authors: F
authors: Prévot
authors: C
authors: C
authors: Grisez
authors: J P
authors: JP
authors: Bergeaud
authors: L
authors: L
authors: Schibler
authors: A
authors: A
authors: Tircazes
authors: D
authors: D
authors: François
authors: C
authors: C
authors: Pery
authors: F
authors: F
authors: Bouvier
authors: J C
authors: JC
authors: Thouly
authors: J C
authors: JC
authors: Brunel
authors: A
authors: A
authors: Legarra
authors: J M
authors: JM
authors: Elsen
authors: J
authors: J
authors: Bouix
authors: R
authors: R
authors: Rupp
authors: C R
authors: CR
authors: Moreno
mesh_terms: D000818:Animals; D001774:Blood Chemical Analysis / Q000662:veterinary; D001947:Breeding; D003433:Crosses, Genetic; D060467:Disease Resistance; D005260:Female; D005602:France; D005819:Genetic Markers; D060005:Genotyping Techniques / Q000662:veterinary; D006188:Haemonchiasis / Q000235:genetics / Q000276:immunology / Q000469:parasitology / Q000662:veterinary*; D006189:Haemonchus / Q000302:isolation & purification; D006400:Hematocrit / Q000662:veterinary; D008297:Male; D018895:Microsatellite Repeats; D020411:Oligonucleotide Array Sequence Analysis / Q000662:veterinary; D010270:Parasite Egg Count / Q000662:veterinary; D059208:Parasite Load / Q000662:veterinary; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D012756:Sheep; D012757:Sheep Diseases / Q000235:genetics* / Q000276:immunology* / Q000469:parasitology
chemical_list: D005819:Genetic Markers