Karel Hála

A three-locus model for the chicken major histocompatibility complex

The major histocompatibility complexes (B complexes) of chickens of various origins have been studied by serological and biochemical methods. TwoB complexes are of particular interest:BR1, a recombinant haplotype derived from theB complexes of the inbred CB and CC strains, andBG-B1, theB haplotype of the G-B1 strain. TheBR1 haplotype differs detectably from theBCB haplotype only at a locus controlling the synthesis of an antigen, B-G, which (in peripheral blood) is present only on red cells. Anti-B-G sera precipitate, from125I-labeled red cell lysates, two chains of apparent molecular weights 42,000 and 31,000 (measured under reducing conditions); the smaller is perhaps derived by proteolysis from the larger. TheBG-B1 haplotype differs detectably from theBCC haplotype only at a locus controlling the synthesis of an antigen whose tissue distribution and biochemical and biological properties are identical to those of B-G. The chicken major histocompatibility complex therefore contains at least three loci—those controlling synthesis of the B-G, and of the previously defined B and B-L antigens.

The MHC haplotypes of the chicken.

The major histocompatibility complex (MHC) of Gallus gallus is the B complex of which three classes of cell-membrane antigens have been clearly defined by serological, histogenetic, and biochemical methods. Two of these classes are homologous to classes I and II of mammals (B-F and B-L, respectively), while the third (B-G) is a differentiation antigen of the erythroid cell-line; the mammalian homologue of this class is still undefined. The B haplotypes comprise at least one gene of each class that displays linkage disequilibrium of a remarkable strength. The present work is the first systematic comparison by serological and histogenetic methods of the allelic products (allomorphs) of 15 haplotypes, including all of the 11 that were accepted as “standard” B haplotypes at the recent international Workshop on the chicken MHC in Innsbruck, Austria. The analysis has revealed many similarities, but only four pairs of probable identities: G2 and G12, F4 and F13, L4 and L13, L12 and L19. It appears therefore that the B-G locus is comparable in its degree of polymorphism to the class I (B-F) locus. The “standard” haplotypes are almost all of White Leghorn derivation, and preliminary typings of other breeds of chickens, and of wild chickens, indicate the existence of a much wider spectrum of allomorphs.

Probable crossing-over in theB blood group system of chickens

Erythrocytes of two chickens from among 1,206 hybrids obtained from a (CB x CC)F1xWB cross reacted with antisera against B antigens of all three lines involved in the cross. The possibility that the two birds had not originated from these crosses was excluded. The irregularity observed in cock 744 is accounted for by assuming a recombinant chromosome, BR1, transmitting part of the B1 and part of the B2 antigenic specificities. Inheritance of B antigens is assumed to be effected by alleles of at least two loci,B-F andB-G. We found that the alleles of theB-F locus determined the serologically defined (SD) and histocompatibility (H) antigens, and the alleles of theB-G locus determined only the SD antigens. The irregularity in theB system of cock 2,349 has not yet been satisfactorily explained.

The structure of the Major Histocompatibility Complex of the Chicken

The major histocompatibility complex (MHC) of the chicken, which had been described as a blood group system (Briles et al. 1950), shortly after its discovery attracted attention of the investigators that the genotype of this genetic system may influence viability, hatchability and a number of economically important traits (Gilmour I960, Briles 1964). When its importance for skin graft survival (Schierman and Nordskog 1961), graft-versus-host reaction (GVHR, Jaffe and McDermid 1962) and mixed lymphocyte reaction (MLR, Miggiano et al. 1974)was found, studies on the structure of the respective region of the chromosome were initiated (Schierman and McBride 1969, Hala et al. 1975).

Immune Response Genes in Chickens: The Multifarious Responsiveness to (T, G)-A--L

Immune response in chickens to the multichain copolymer (T,G)-A--L 2030 is analysed. Previous work has shown that responsiveness is not linked to the B-complex. Three different antibody specificities could be distinguished. From the data it is proposed that the response to the backbone of (T,G)-A--L (poly-DL-alanine) influences the responses to the side chain determinants (primarily the (T,G)-determinant). Thus the anti-(T,G) response in chickens is determined by at least two different loci, the B-complex, and another, as yet unidentified locus which determines the response to the poly-DL-alanine determinant. A third antibody specificity is directed against G-A--L and is only detectable in chickens which are high responders to poly-DL-alanine.

A spontaneous chicken chimaera

Among hybrids of the inbred lines, a chicken was found to be chimaeric in red blood cells and skin cells and to produce 3 types of sperm cells. This bird could have originated either from the fusion of 2 blastoderms or from the fertilization and fusion of the oocyte and the 2nd polar body.