Class I and class II major histocompatibility complex alleles are associated with faecal egg counts following natural, predominantly Ostertagia circumcincta infection.
During a previous investigation an association was found between major histocompatibility complex (MHC)-DRB1 alleles and faecal egg counts following natural infection predominantly involving Ostertagia circumcincta in a flock of Scottish Blackface sheep. To localise the disease-resistance locus we screened the same flock for an MHC class I microsatellite and a newly developed microsatellite for the DY locus located in the class IIb subregion. Some alleles at both additional loci were associated with resistance to infection. Least-squares analysis of variance indicated that in 6-month-old lambs, substitution of the most common alleles by the alleles associated with resistance would result in an 8- and a 218-fold reduction in faecal egg counts for MHC class I and DY, respectively. These results indicate that genes within the MHC genes play a large and significant role in the development of resistance to a widespread, important and natural parasite.
Department of Animal Breeding, Technical University Munich, Germany. buitkamp@pollux.edv.agrar.tu-muenchen.de
J
J
Buítkamp
P
P
Filmether
M J
MJ
Stear
J T
JT
Epplen
D000483:Alleles; D000818:Animals; D005243:Feces / Q000469:parasitology; D005260:Female; D005805:Genes, MHC Class I; D005802:Genes, MHC Class II; D006790:Host-Parasite Interactions; D008297:Male; D018895:Microsatellite Repeats; D010028:Ostertagia / Q000276:immunology*; D010029:Ostertagiasis / Q000276:immunology*; D010270:Parasite Egg Count; D012756:Sheep