title: Allelic variation of ovine MHC class II DQA1 and DQA2 genes.
abstract: In the present study we characterize allelic variation of polymorphic OLA-DQA1 and OLA-DQA2 genes in sheep. To achieve this, PCR primers were designed to independently amplify the second exons of OLA-DQA1 and OLA-DQA2 genes. Single strand conformation polymorphism (SSCP) gel analyses reveals that there are at least 12 distinct OLA-DQA2 sequences, 10 of which have been characterized by sequencing. Six distinct OLA-DQA1 alleles have been sequenced in sheep and we can detect at least seven DQA1 alleles, including a null allele, by SSCP analysis. The second exon of the OLA-DQA2 gene is more polymorphic than the equivalent region of the OLA-DQA1 gene. Thirty-two per cent of nucleotide and 49% of amino acid sites showed variation at the DQA2 locus, compared to 20% of nucleotide and 33% of amino acid sites for DQA1. Phylogenetic analysis of DQA sequences from a number of species show that sheep DQA1 sequences group together and are more similar to bovine DQA1 sequences than to sheep DQA2 alleles. The majority of OLA-DQA2 sequences are on the same main branch of the phylogenetic tree as bovine DQA2 sequences. However, three sheep DQA2 sequences have a tendency to group with putative bovine DQA3 sequences rather than to other ovine DQA2 alleles. A variety of SSCP gel conditions were tried in order to develop a typing system for the OLA-DQA2 gene. We describe a set of PCR and SSCP conditions which distinguish between all known OLA-DQA2 alleles.
authors.affiliation: Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Parkville, Victoria, Australia.
authors.forename: K J
authors.initials: KJ
authors.lastname: Snibson
authors.forename: J F
authors.initials: JF
authors.lastname: Maddox
authors.forename: S A
authors.initials: SA
authors.lastname: Fabb
authors.forename: M R
authors.initials: MR
authors.lastname: Brandon
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D017931:DNA Primers / Q000235:genetics; D005091:Exons; D005802:Genes, MHC Class II; D014644:Genetic Variation; D005838:Genotype; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D018807:Polymorphism, Single-Stranded Conformational; D017386:Sequence Homology, Amino Acid; D012756:Sheep / Q000235:genetics* / Q000276:immunology*; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D000949:Histocompatibility Antigens Class II