title: Identification and phylogenetic analysis of 15 MHC class II DRB1 beta1 expressed alleles in a ewe-lamb flock.
abstract: Ovar-DRB1 is part of the major histocompatibility complex (MHC) class II of sheep and functions by presenting extracellular-derived peptides to the immune system. Although there are over 100 different Ovar-DRB1 DNA sequences reported in GenBank, only two Ovar-DRB1 mRNA sequences have been reported. As a first step in understanding MHC Class II function as it relates to disease progression in sheep, Ovar-DRB1 transcripts encoding the peptide-binding site or the first domain (beta1) of Ovar-DRB1 in a 32-ewe-lamb flock were identified and characterized by using reverse transcriptase-polymerase chain reaction, cloning, sequencing, and phylogenetic analysis. Fourteen new Ovar-DRB1 beta1 cDNA sequences out of a total of 15 Ovar-DRB1 beta1 cDNA sequences in a ewe-lamb flock of 32 sheep were identified. One Ovar-DRB1 beta1 cDNA sequence was 100% identical to M93432, one of the two Ovar-DRB1 mRNA sequences reported in GenBank. Twelve out of 15 Ovar-DRB1 beta1 cDNA sequences were 100% identical to the corresponding previously reported Ovar-DRB1 genomic DNA sequences, indicating that these Ovar-DRB1 genomic DNA sequences are also transcribed. One of three of the remaining Ovar-DRB1 beta1 cDNA sequences, DRB1*07012, had a synonymous substitution resulting in an identical deduced amino acid sequence to DRB1*0701. Two of the remaining three Ovar-DRB1 beta1 cDNA sequences had nucleotide differences and subsequent deduced amino acid sequence differences when compared to known Ovar-DRB1 beta1 genomic DNA sequences, and therefore, DRB1*0206 and DRB1*0353 represent new Ovar-DRB1 beta1 expressed alleles. Phylogenetic analysis of the 15 Ovar-DRB1 beta1 cDNA sequences revealed that DRB1*0206 had a strong phylogenetic relationship to DRB1*0203, and DRB1*0353 had a strong phylogenetic relationship to DRB1*0303.
authors.affiliation: Animal Disease Research Unit, USDA-ARS, 3003 ADBF, Washington State University, Pullman, 99164-6630, USA. lherman@vetmed.wsu.edu
authors.forename: Lynn M
authors.initials: LM
authors.lastname: Herrmann
authors.forename: Wendy C
authors.initials: WC
authors.lastname: Brown
authors.forename: Greg S
authors.initials: GS
authors.lastname: Lewis
authors.forename: Donald P
authors.initials: DP
authors.lastname: Knowles
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D016384:Consensus Sequence; D005091:Exons; D005802:Genes, MHC Class II; D014644:Genetic Variation; D006684:HLA-DR Antigens / Q000737:chemistry / Q000235:genetics*; D059811:HLA-DRB1 Chains; D008969:Molecular Sequence Data; D010802:Phylogeny; D011110:Polymorphism, Genetic; D012689:Sequence Homology, Nucleic Acid; D012756:Sheep / Q000235:genetics*
chemical_list: D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains