BoLA-DIB: species distribution, linkage with DOB, and northern analysis

The bovine major histocompatibility complex differs from that of other species in that it has a second group of class II genes that are separated from the classical class I/class II complex by 15 to 20 centimorgans. Two class II bovine genes, BoLA-DYA and BoLA-DIB, seem to be unique based on sequence analysis. To investigate the occurrence of one of these genes, BoLA-DIB, in other species, a DIB 2nd domain exon probe was hybridized to Southern genomic blots containing DNA from representatives from a variety of mammalian families. The probe hybridized only with DNA from representatives of the Cervidae, Giraffidae and Bovidae families, indicating that significant sequence similarity to DIB may be confined to these families. Analysis of the linkage relationship between DIB and DOB in cattle half-sib families did not yield any recombinants among 39 informative offspring, indicating that DIB maps within the second group of class II bovine genes; DOB has previously been mapped to the second group of class II genes. A 1st domain exon probe from BoLA-DQB hybridized to RNA from either stimulated or unstimulated peripheral bovine lymphocytes, while 1st domain exon probes from BoLA-DIB and HLA-DOB gave no hybridization signals, indicating that transcription in peripheral lymphocytes of these genes is at least very minor compared to BoLA-DQB.