Nutritional modulation of immune function in broilers.

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

Influence of the Major Histocompatability Complex on Disease Resistance and Productivity

Various strains of infectious bronchitis virus (IBV) cause respiratory, kidney, enteric and reproductive illnesses in chickens, especially in newly hatched chicks. Assays have been developed to identify Gray strain IBV-specific cytotoxic T lymphocyte (CTL) responses using viral infected antigen presenting cells (APC) and using the Semliki Forest virus vector infected APC expressing individual viral polypeptides. It was shown that major histocompatibility complex restricted CTL are responsible for early control of IBV infection. The kinetics of viral load observed in the lungs and kidneys correlated with the level of IBV-specific CTL activity of effector cells prepared from spleens of infected chicks. Adoptive transfer of immune T cells to chicks prior to infection demonstrated that IBV primed CD8(+), alphabeta T lymphocytes could protect chicks from acute infection. CTL determinants in the viral particle can be mapped to the spike and nucleocapsid proteins but not to the membrane protein. The carboxyl terminus of the nucleocapsid protein houses an epitope(s) responsible for induction of CTL responses to IBV N protein. Inoculation of DNA plasmid expressing the carboxyl terminus of Gray strain N resulted in induction of CTL that cross-react with two distinct IBV strains. In addition, this potential DNA vaccine resulted in protection of chicks against acute infection.

Cytotoxic T lymphocytes are critical in the control of infectious bronchitis virus in poultry.

Recent progress on the cytokine regulation of intestinal immune responses to Eimeria

The fate of tumors induced by Rous sarcoma virus (RSV) was determined in anF
2 population segregating at three alloantigen loci. TheF
1 resulted from crossing tumor-resistant RPRL line 61 (B
2
B
2
D
3
D
3
I
2
I
2) with tumor-susceptible RPRL line 151 (B
5
B
5
D
4
D
4
I
8
I
8). Among theF
2 segregantsB
2
B
2,B
2
B
5, andB
5
B
5, the percentage of chicks dying of terminal tumors (by 70 days post-inoculation) was 5, 26, and 93, respectively (P≦0.01). NeitherD orI genotypes nor sex significantly affected tumor growth. In chickens with terminal tumors, the incidence of metastatic lesions was also significantly associated withB genotypes. Thus, the MHC chromosomal region in the chicken appears to exert a crucial role in determining the outcome of RSV-induced tumors.

TheB locus (MHC) in the chicken: Association with the fate of RSV-induced tumors

Chickens of Regional Poultry Research Laboratory (RPRL) inbred line 63 regress sarcomas induced by Bryan high-titer Rous sarcoma virus to a greater extent than chickens of line 72, although these lines are identical for the major histocompatibility complex (MHC, B complex). They differ, however, at two independent autosomal loci, Ly-4 and Th-1, which determine surface alloantigens of partly overlapping subsets of T lymphocytes. Association of genotypes at these loci with quantitative variation in ability to regress Rous sarcomas was tested in segregating progeny derived from crosses of lines 63 and 72. In the F4 generation chickens of the Ly-4 a /Ly-4 a , Th-1 a /Th-1 a genotype (symbolized aa/aa) had significantly higher regressor ability than any of the other three double homozygous genotypes. In F5, all nine genotypes formed by combinations of homozygotes and heterozygotes were tested, and higher regressor ability was shown by the aa/aa, ab/aa, and aa/ab genotypes. These results indicate that higher regression is associated with: (1) interaction between the line 63Ly-4 a and Th-1 a alleles in homozygous form; and (2) dominance x dominance interaction, in that the a allele at each locus is dominant for higher regression only within the homozygous aa genotype at the other locus.

Influence of Non-MHC T Lymphocyte Alloantigens on Regression of Rous sarcomas in the Chicken

The incidence of regression of Rous sarcoma virus (RSV)-induced tumors in a noninbred line of New Hampshire chickens was approximately six percent (Cotter et al. 1973, Collins et al. unpublished data). But in a mating of one sire with two dams from this line, the mean incidence of tumor regression (of 30 progeny developing tumors) was 50 percent (Collins et al. unpublished data). Thus, although essentially a progressor line, certain individuals transmitted genes favorable to tumor regression. More recently Collins and co-workers (1977) studied the fate of RSVinduced tumors in an F 2 population from a cross of RPRL inbred lines 61 and 151 which was segregating at three alloantigen loci(B, D and I). Among the F 2 segregants B:B 2, B:B 5, and BSB 5 the percentage of chickens dying of terminal tumors by 70 days post inoculation was 5, 26 and 93, respectively. Seventy-five percent of B:B 2 chickens completely or partially regressed their tumors in contrast to none of the BSB 5 animals. The D and I loci had no detectable effect on tumor regression. Schiermann and co-workers (1977) concluded that regression of RSV-induced tumors was a dominantly inherited trait controlled by a gene within, or closely linked to, the major histocompatibility complex (MHC). Thus, in the chicken the MHC, for which the B blood group system serves as a marker, has a gene(s) which dramatically affects the fate of RSV-induced tumors. The objective of this research was to determine the effect of genes in the immediate chromosomal region of the MHC on tumor regression in this line of New Hampshires. Chickens were produced in two hatches from a flock mating of a noninbred line of New Hampshires, U N H 105, known to be genetically susceptible to subgroup A RSV. Chicks were blood typed for B alloantigens at 4 weeks of age using reagents developed in stocks originating from inter se matings of crosses between White Leghorns and experimental birds of heavy breed origin. Three alleles, B 23, B 24 and B 26 had been previously established as existing in this line (Brilles, unpublished). Using appropriate reagents, the 131 chicks from the two hatches were classified into six genotypes-B23B 23, B24B 24, B26B 26, B23B24, B2SB 26, and B24B26. A highly purified pseudotype of Bryan high-titer Rous sarcoma virus designated BH RSV(RAV-1),

Kathy K. Clark

Papers

TheB locus (MHC) in the chicken: Association with the fate of RSV-induced tumors

Influence of Non-MHC T Lymphocyte Alloantigens on Regression of Rous sarcomas in the Chicken

B locus (MHC) effect upon regression of RSV-induced tumors in noninbred chickens

Host Age and Major Histocompatibility Genotype Influence on Rous Sarcoma Regression in Chickens