Allelic nomenclature for the duplicated MHC class II DQ genes in sheep
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The principal MHC class II molecules involved in the presentation of peptides to the antigen specific receptors on CD4+ T cells genes in sheep are derived from DR and DQ genes. Allelic nomenclature systems for the DRB1 and its partner DRA loci are available for Ovid’s; however, no official nomenclature is available for the DQ genes which creates ambiguity within the research community. Ovine MHC haplotypes include at least two pairs of DQA and DQB genes, termed DQA1, DQB1 and DQA2, DQB2 and both sets are polymorphic and both seem to be functional. In a number of haplotypes, the DQA1 locus appears to be absent (DQA1-null) and is replaced by a second locus termed DQA2-like. Here, we identify families of alleles based on sequence similarity and phylogenetic clustering which correspond to each of the DQA and DQB genes identified in previous genomic and transcript analyses of homozygous animals. Using such criteria to cluster sequences, we have named 82 full-length and partial cDNA transcripts derived from domestic sheep (Ovis aries) which correspond to alleles at the Ovar-DQA1, DQA2, DQA2-like, DQB1, DQB2 and DQB2-like genes and provide associated sequence resources available to the research community through the IPD-MHC Database. This sets the basis for naming and annotation of DQ genes within the ovine MHC and may be used as a template for DQ genes in other ruminant species which will ultimately support research in livestock infectious disease.
KeywordsSheep MHC class II DQ Nomenclature IPD-MHC
The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7, 2007-2013), Research Infrastructures action, under the grant agreement No. FP7-228394 (NADIR) and European Union’s Horizon 2020 research and innovation programme under grant agreement no. 731014 (VetBioNet). KB receives support from the Scottish Government’s strategic research programme. The IPD-MHC project receives funding from the Biotechnology and Biological Sciences Research Council (BBSRC) under grant (BB/M011488/1). Thesupport provided by Giuseppe Maccari in processing the sequence data into the IPD-MHC Database is gratefully acknowledged. The work of the IPD-MHC Databases is supported by the European Molecular Biology Laboratories, the International Society for Animal Genetics. (ISAG) and the Veterinary Immunology Committee (VIC) of the International Union of Immunological societies (IUIS).
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