Major Histocompatibility Complex class IIB polymorphism in an ancient Spanish breed

Abstract

Genes from the Major Histocompatibility Complex class II region are involved in the presentation of antigens. Therefore, they have the key role in regulating the immune response and in the resistance to infections. We investigated the Major Histocompatibility Complex class IIB genes, DRB and DQB, in Churra sheep, one of the most important indigenous breeds of Spain. These genes are among the most polymorphic in the mammalian genome. Furthermore, often different numbers of class IIB genes per haplotype exist, complicating the genotyping and sequencing of these genes. Especially the DQB region is only partially characterized in sheep and the repertoire of DRB and DQB alleles in Churra sheep, an ancient breed, is unknown. Here, we sequenced the class IIB genes for 15 rams that are the pedigree heads of a selection Nucleus herd. In total, we found 12 DRB and 25 DQB alleles. From these, 3 and 15 were new, respectively. Fourteen haplotypes carrying one or two DQB alleles could be deduced and the evolutionary relationship of these was investigated by phylogenetic trees. Based on the sequences of these most common class II alleles, a more efficient genotyping system for larger numbers of Churra sheep will be developed.

A novel technique for retrospective genetic analysis of the response to vaccination or infection using cell-free DNA from archived sheep serum and plasma

“…It is worth noting that homozygosity at the DRB1 locus does not mean that the animal is always homozygous across the MHC class II region. The ovine MHC class II region includes a range of polymorphic DQ loci [38] and a number of studies have identified diversity at the duplicated DQA and DQB loci linked with identical DRB1 alleles [4].…”

“…To demonstrate the utility of the method, we sought to determine whether genomic DNA could be obtained from archived plasma samples, and tested if alleles of the Ovar-MHC class II locus could be amplified from these samples. We focussed on the DRB1 locus which is the most highly polymorphic MHC class II locus of domestic sheep (Ovis aries) [4,5]. The MHC class II genes encode dimeric cell surface glycoproteins that present peptides to the adaptive immune system for recognition by CD4+ T cell receptors [6,7].…”

“…The MHC class II genes encode dimeric cell surface glycoproteins that present peptides to the adaptive immune system for recognition by CD4+ T cell receptors [6,7]. MHC class II diversity plays an important role in determining the type and intensity of the immune response to foreign antigens within a population [4].…”

Immunogenomics of gastrointestinal nematode infection in ruminants – breeding for resistance to produce food sustainably and safely

“…This region was highlighted is a meta‐analysis of 3 diverse sheep breeds (Scottish Blackface, Sarda × Lacaune and Martinik Black‐Belly × Romane) using RHM methodologies with a 100‐SNP window . The most studied gene of the MHC complex is DRB1 . Conversely, the highly polymorphic nature of this region (over 80 known alleles) and the significant role that it plays in the spectrum of immune‐mediated genetic disease are likely to make it difficult to identify SNPs that will be useful for selecting for GIN resistance without affecting susceptibility to other traits .…”

“…105 The most studied gene of the MHC complex is DRB1. 61,79,107,121 Conversely, the highly polymorphic nature of this region (over 80 known alleles) and the significant role that it plays in the spectrum of immune-mediated genetic disease are likely to make it difficult to identify SNPs that will be useful for selecting for GIN resistance without affecting susceptibility to other traits. 114 Many studies have yielded an association between this chromosomal region and parasite resistance traits, but several more have not.…”