Evidence for at least three transcribed BoLA class I loci

Abstract

Serological data identify a single major histocompatibility complex (MHC) class I locus in cattle. Molecular data, however, demonstrate the presence of at least two cattle MHC (BoLA) class I loci. To investigate the number of transcribed BoLA class I genes, we amplified cattle cDNA by using a single MHC class I-specific primer that hybridized to a conserved region of exon 4 and a non-specific 3' primer. Six BoLA class I cDNAs have been cloned and sequenced from a Bos taurus bull heterozygous for BoLA class I serological antigens, demonstrating the presence of a minimum of three loci. Sequence comparisons suggested that one of these cDNAs may be an unexpressed allele or the product of a nonclassical locus.

HLA-B alleles of the Cayapa of Ecuador: new B39 and B15 alleles

“…Amplifications were carried out using a Perkin Elmer model 9600 thermocycler. PCR products were cloned into pSP65 (Melton et al 1984;Promega, Madison, WI) and sequenced with Sequenase (US Biochemicals, Cleveland, OH) using a slight modification of the manufacturer's method (Sanger et al 1977;Garber et al 1994). At least three copies of each allele were sequenced.…”

cDNA sequence of cattle MHC class I genes transcribed in serologically defined haplotypes A18 and A31

“…Since 1988, eleven BoLA class I nucleotide sequences have been published (Ennis et al 1988;Brown et al 1989;Bensaid et al 1991;Garber et al 1994;Sawhney et al 1995). Despite this, it still remains unclear how many classical class I loci are present in the cattle genome, whether the number and nature of genes transcribed is consistent between haplotypes and breeds, and whether the products of the different genes carry out exactly the same function.…”

“…Our aim in this study was to carry out a detailed analysis of well-defined class I haplotypes, using cDNA cloning, sequence analysis, and transfection/expression studies in order to identify the genes coding for the ubiquitously expressed, antigen presenting class I molecules. Alternative approaches have been described, for example polymerase chain reaction amplification of class I sequences from cDNA (Garber et al 1994), and identification of expressed genomic clones (Sawhney et al 1995) but neither of these methods provides information regarding the level of transcription of individual genes.…”

“…HD1 is almost identical to BSX in the alpha 1 domain, having only two amino acid differences (positions 35 and 49), although there are a Fig. 2 Predicted amino acid sequences of seven cattle class I cDNAs -BSX and Bslb are included for comparison (Garber et al 1994).…”

“…HD1, HD15, and HD7 are all on the A31 haplotype, demonstrating that they are the products of three loci (Ellis and co-workers, unpublished data)• Previous attempts to assign BoLA class I sequences to defined loci have failed (Garber et al 1994), partly due to the lack of locus-specific characteristics. Phylogenetic analysis on small numbers of sequences (Garber et al 1994), and earlier studies of partial sequences (Ellis et al 1992), showed that variations in TM length may give an indication of locus of origin.…”