Tests of association of lymphocyte alloantigen genotypes with resistance to viral oncogenesis in chickens. 1. Marek's disease in F7 progeny derived from 6(3) X 15(1) crosses

Immune effects of chicken non-MHC alloantigens

Alloantigen systems are a broad group of molecules found on various cell types, including erythrocytes and lymphocytes. These alloantigens, identified via specific polyclonal or monoclonal antibodies or molecular methods, have demonstrated effects on immune responses. Erythrocyte alloantigens include the A, B, C, D, E, H, I, J, K, L, N, P, and R systems. Highly polymorphic alloantigen B has been identified as the chicken major histocompatibility complex (MHC). The other twelve systems have a variable degree of polymorphism as well as impact on immune measurements or responses against pathogens. Selection for immune characters altered allele frequencies for particular alloantigen systems. Three lymphocyte alloantigens, Bu-1, Ly-4 and Th-1 have more limited polymorphism but still influence responses against viral pathogens, Rous sarcoma virus and Marek's disease. Together, these erythrocyte and lymphocyte systems contribute to the overall immunity. Identification of the specific alloantigen proteins remains crucial to understanding their immune contribution.

Marek's disease and major histocompatibility complex haplotypes in chickens selected for high or low antibody response

Sublines of chickens differing in genotypes at the major histocompatibility complex (MHC) were developed from lines selected for high (HA) and low (LA) antibody response to sheep erythrocytes. To evaluate the influence of MHC genotypes in diverse background genomes on resistance to Marek's disease, chicks with MHC genotypes B13B13, B13B21 and B21B21 from both background genomes were exposed naturally commencing at 1 day of age. Individuals which died up to 120 days of age were autopsied to determine cause of death. Mortality due to Marek's disease was greater for HA than LA chickens and greater for males than females. Interactions of MHC genotypes with background genome and with sex suggest a complex picture of the influence of MHC genotypes. A heterozygous advantage for resistance to Marek's disease was noted, as would be predicted by genetic theory concerning maintenance of polymorphism at the MHC.

A review of the development of chicken lines to resolve genes determining resistance to diseases

The resolution of genes that determine resistance to disease is described using chicken lines maintained at the Avian Disease and Oncology Laboratory (ADOL). This description includes a summary 1) of existing selected and inbred lines differing for resistance to viral-induced tumors, i.e., Marek's disease (MD) and lymphoid leukosis (LL), and of the use of inbred and line crosses to define relevant disease-resistant genes, e.g., TV, ALVE, B, R, LY4, TH1, BU1, and IGG1; 2) of the development of TVB*/ALVE congenic lines to establish the affects of endogenous virus (EV) expression on resistance to avian leukosis virus (ALV), and methods to detect ALVE expression; 3) of the development of B congenic lines to define the influence of the MHC on MD resistance and vaccinal immunity, for producing B antisera, and for evaluating DNA sequences of Class I and II genes; and 4) of the current development of 6C.7 recombinant congenic strains (RCS) to define the role of non-MHC genes influencing susceptibility to MD and LL tumors, immune competence, and epistatic effects of genes. The procedures of pedigree mating, to avoid or maintain inbreeding, and of blood-typing, to ensure genetic purity of the lines, are also described.

Nonmajor histocompatibility complex alloantigen effects on the fate of Rous sarcomas

Rous sarcoma virus-induced tumor outcome is controlled by the MHC (B). Additional data, using controlled segregation in families, has indicated non-MHC effects as well, but few studies have focused on blood groups other than the B complex. Segregating combinations of genes encoding erythrocyte (Ea) alloantigen systems A, C, D, E, H, I, P, and L in B2B5 and B5B5 MHC (B) backgrounds were examined for their effects on Rous sarcomas. Six-week-old chickens were inoculated in the wing-web with 30 pfu of Rous sarcoma virus (RSV). Tumors were scored six times over a 10-wk period. A tumor profile index (TPI) was assigned to each chicken based on the six tumor size scores. Response was evaluated using tumor size at each measurement period, TPI, and mortality. The genotypes of Ea systems A, C, D, E, H, I, and P had no significant effect on any parameter in either B complex population. The Ea-L system had an effect on Rous sarcomas in the B2B5 intermediate responders and B5B5 progressors. Tumor size, TPI, and mortality were all significantly lower in B2B5 L1L1 chickens than in B2B5 L1L2 chickens. Mortality was lower in the B5B5 L1L1 birds than in B5B5 L1L2 chickens. It appears that the Ea-L system, or one closely linked, is acting in a manner independent of the B complex in response to RSV challenge.

Genetic interaction between non-MHC T- and B-cell alloantigens in response to Rous sarcomas in chickens

Chickens of Regional Poultry Research Laboratory (RPRL) inbred line 6(3) regress sarcomas induced by Bryan high-titer Rous sarcoma virus to a greater extent than chickens of line RPRL 100, although these lines are identical for the major histocompatibility B complex. They differ, however, at three independent autosomal loci: Ly-4 and Th-1 determine the surface alloantigens of partly overlapping subsets of T lymphocytes, and Bu-1 determines a surface alloantigen of B lymphocytes. The association of genotypes at these loci with quantitative variation in their ability to regress Rous sarcomas was tested in segregating F4 generation progeny derived from crosses of lines 100 and 6(3). The Ly-4 and Bu-1 genotypes showed association with Rous sarcoma regression, but the Th-1 genotype did not. Chickens of the Ly-4a/Ly-4a, Bu-1b/Bu-1b and Ly-4b/Ly-4b, Bu-1a/Bu-1a genotypes had a significantly higher regressor ability than the other two double homozygous genotypes. These results indicate that higher regression is associated with (1) interaction between the Ly-4 and Bu-1 loci, and (2) complementation between either the line 6 Ly-4a allele and the line 100 Bu-1b allele, or the line 100 Ly-4b allele and the line 6 Bu-1a allele.