The major and a minor class II beta-chain (B-LB ) gene flank the Tapasin gene in the B-F /B-L region of the chicken major histocompatibility complex.
We have identified the major histocompatibility complex class II beta-chain (B-LB) genes present in the B-F/B-L region of the B complex of nine well-characterized lines of chickens and have cleared up much of the confusion concerning numbers and location of B-LB genes in this region. By amplifying DNA sequences between adjacent genes, we found two B-LB genes that lie on either side of Tapasin. The dominantly expressed 'major' B-LB gene in all haplotypes lies between Tapasin and RING-3, and belongs to the B-LBII family of class II beta-chain genes. The poorly expressed 'minor' B-LB gene in all haplotypes lies between B-lec1 and Tapasin, and belongs either to the B-LBII family or to the previously unmapped B-LBVI family of class II beta-chain genes. The data suggest that the B-LBII and B-LBVI genes are two lineages of B-LB genes and we propose that they all be termed B-LB genes. The location of a third B-LB gene in the B12 haplotype (and possibly other haplotypes as well) has yet to be determined. The structural organization and expression of the class II beta-chain genes in the B-F/B-L region is similar to that of chicken class I (B-F) genes, one functional result of which is differential resistance to disease and response to vaccines.
Jacob
J P
JP
Institute of Animal Health, Compton, Berkshire, RG20 7NN, UK.
Milne
S
S
Beck
S
S
Kaufman
J
J
D000818:Animals; D017849:Animals, Inbred Strains; D017920:Antiporters / Q000235:genetics*; D001483:Base Sequence; D002645:Chickens / Q000235:genetics* / Q000276:immunology; D005091:Exons / Q000235:genetics; D018628:Gene Dosage; D005799:Genes, Dominant / Q000276:immunology; D005802:Genes, MHC Class II / Q000235:genetics*; D008040:Genetic Linkage; D015235:HLA-B Antigens / Q000235:genetics*; D006239:Haplotypes / Q000235:genetics; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D007136:Immunoglobulins / Q000235:genetics*; D007438:Introns / Q000235:genetics; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D020161:Physical Chromosome Mapping; D011110:Polymorphism, Genetic / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid
D017920:Antiporters; D015235:HLA-B Antigens; C088036:HLA-B67 antigen; D000949:Histocompatibility Antigens Class II; C041136:Ia-like antigens, avian; D007136:Immunoglobulins; D026901:Membrane Transport Proteins; C107762:tapasin