B-G cDNA clones have multiple small repeats and hybridize to both chicken MHC regions

Abstract

We used rabbit antisera to the chicken MHC erythrocyte molecule B-G and to the class I alpha chain (B-F) to screen lambda gt11 cDNA expression libraries made with RNA selected by oligo-dT from bone marrow cells of anemic B19 homozygous chickens. Eight clones were found to encode B-G molecules which hybridize with sequences in the chicken MHC as defined by congenic strains; the fusion proteins react with multiple immune but not preimmune sera, they select antibodies from the antisera to B-G, which then react with distinct erythrocyte B-G protein patterns, and they elicit antibodies from mice which in turn react with authentic B-G proteins. None of the clones represent a complete message, some--if not all--bear introns, and none of them match with any sequences presently stored in the data banks. The following new information did, however, emerge. At least two homologous transcripts are present in this homozygous chicken, thereby formally proving the existence of an expressed multigene family. The 3' ends (3'UT) are simple sequences with 80% nucleotide identity between clones, while the 5' ends (either coding or noncoding) are composed of multiple short repeats which are far less similar. These repeats could explain the bewildering variation in size of B-G proteins within and between haplotypes. Southern blots of genomic chicken DNA gave complex patterns for most probes, with many bands in common using different probes, but few bands in common between haplotypes. The sequences detected are all present in the MHC, based on the congenic lines CB and CC. Most of these sequences map into the B-G region, but some map into the B-F/B-L region as defined by the haplotypes B15, B21, and their apparently reciprocal recombinants B21r3 and B15r1.

Rapid Detection of BF Haplotypes by a Semi‐nested Polymerase Chain Reaction, which Causes Resistance/Susceptibility to Marek’s Disease in Chicken

“…In the first round of amplification of BF genes, a 195-bp product and a 162-bp product from all tissues of the A 5 and B 21 homozygous Xiayan chickens were obtained, while only a 195-bp product from all tissues of the A 11 , C 23 , D 8 and D 12 homozygous Xiayan chickens was obtained. The nucleotide sequences of these amplified products representing mRNA transcripts of BF genes from the 195-bp product of the D 12 (GenBank accession numbers: EU746446) and the 162-bp product of the A 5 (GenBank accession numbers: EU746447) Xiayan chickens were listed in Fig.…”

“…PBL of the susceptible homozygous Xiayan chickens A 5 and B 21 and the resistant homozygous Xiayan chickens A 11 , C 23 , D 8 and D 12 were sampled on day 21 post-MD infection [18]. Liver, spleen and heart were sampled on the day of killing [18].…”

“…BF is equivalents of the mammalian MHC class I [12]. All cell types in the chicken express BF, and they are thought to play a central role in MHC-restricted antigen presentation to cytotoxic T cells [13,14].…”

Different Evolutionary Histories of the Two Classical Class I Genes BF1 and BF2 Illustrate Drift and Selection within the Stable MHC Haplotypes of Chickens

“…Genomic DNA from seven inbred lines of chickens with defined MHC type (line 6 1 (B2), line C-B4 (B4), line C-B12 (B12), line WL (B14), line 15I 5 (B15), line P2a (B19), line N (B21)) were digested with EcoRV and NotI, and Southern blots were performed as described, washing with 0.2ϫ SSC (30,31). The 550-bp DMB2 probe was produced by cutting a DMB2 genomic clone (derived from line 6 1 DNA by PCR, Ref.…”

Histocompatible Chicken Inbred Lines: Homogeneities in the Major Histocompatibility Complex Antigens of the GSP, GSN/1, PNP/DO and BM-C Inbred Lines Assessed by Hemagglutination, Mixed Lymphocyte Reaction and Skin Transplantation

“…The B-G region is closely linked to the B-L/B-F region that encodes erythrocytespecific antigens and has no equivalent in mammals [10]. The B-G region is at least as polymorphic as the other regions, but its function remains unknown [12]. The B-L/ B-F regions have all the attributes of the MHC, which are comparable to those of mammals and determines rapid allograft rejection, strong mixed lymphocyte reaction (MLR) and cellular cooperation in the immune response [26,38,39].…”