Diet and immunological memory of lines of White Leghorn chickens divergently selected for antibody response to sheep red blood cells

CD99 and the Chicken Alloantigen D Blood System

The chicken D blood system is one of 13 alloantigen systems found on chicken red blood cells. Classical recombinant studies located the D blood system on chicken chromosome 1, but the candidate gene was unknown. Multiple resources were utilized to identify the chicken D system candidate gene, including genome sequence information from both research and elite egg production lines for which D system alloantigen alleles were reported, and DNA from both pedigree and non-pedigree samples with known D alleles. Genome-wide association analyses using a 600 K or a 54 K SNP chip plus DNA from independent samples identified a strong peak on chicken chromosome 1 at 125-131 Mb (GRCg6a). Cell surface expression and the presence of exonic non-synonymous SNP were used to identify the candidate gene. The chicken CD99 gene showed the co-segregation of SNP-defined haplotypes and serologically defined D blood system alleles. The CD99 protein mediates multiple cellular processes including leukocyte migration, T-cell adhesion, and transmembrane protein transport, affecting peripheral immune responses. The corresponding human gene is found syntenic to the pseudoautosomal region 1 of human X and Y chromosomes. Phylogenetic analyses show that CD99 has a paralog, XG, that arose by duplication in the last common ancestor of the amniotes.

Assessment of trade-offs between feed efficiency, growth-related traits, and immune activity in experimental lines of layer chickens

Background

In all organisms, life-history traits are constrained by trade-offs, which may represent physiological limitations or be related to energy resource management. To detect trade-offs within a population, one promising approach is the use of artificial selection, because intensive selection on one trait can induce unplanned changes in others. In chickens, the breeding industry has achieved remarkable genetic progress in production and feed efficiency over the last 60 years. However, this may have been accomplished at the expense of other important biological functions, such as immunity. In the present study, we used three experimental lines of layer chicken—two that have been divergently selected for feed efficiency and one that has been selected for increased antibody response to inactivated Newcastle disease virus (ND3)—to explore the impact of improved feed efficiency on animals’ immunocompetence and, vice versa, the impact of improved antibody response on animals’ growth and feed efficiency.

Results

There were detectable differences between the low (R+) and high (R−) feed-efficiency lines with respect to vaccine-specific antibody responses and counts of monocytes, heterophils, and/or T cell population. The ND3 line presented reduced body weight and feed intake compared to the control line. ND3 chickens also demonstrated an improved antibody response against a set of commercial viral vaccines, but lower blood leucocyte counts.

Conclusions

This study demonstrates the value of using experimental chicken lines that are divergently selected for RFI or for a high antibody production, to investigate the modulation of immune parameters in relation to growth and feed efficiency. Our results provide further evidence that long-term selection for the improvement of one trait may have consequences on other important biological functions. Hence, strategies to ensure optimal trade-offs among competing functions will ultimately be required in multi-trait selection programs in livestock.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12711-021-00636-z.

Phenotypic responses of chickens to long-term selection for high or low antibody titers to sheep red blood cells

A long-term bidirectional selection experiment was conducted to study antibody response to SRBC. Lines, high antibody selection (HAS) and low antibody selection (LAS), originating from the same White Leghorn base population had undergone 37 generations of selection for either high or low antibody response 5 d after a single intravenous injection of 0.1 mL of a 0.25% suspension of SRBC antigen. Subpopulations, where selection was relaxed, were maintained as contemporaries with the selected lines from generations 16 to 24 [high antibody relaxed (HAR) and low antibody relaxed (LAR)] and 24 to 37. Body weights were obtained at 4, 24, and 38 wk of age and at the onset of lay (BW at first egg). Also measured were age in days to first egg, percentages of hen-day ovulations and normal egg production, and percentages of normal and defective eggs from total ovulation (PNE and PDE). Selection lead to a large divergence in antibody titers between the selected lines, with a plateau reached in line LAS. Line HAS and HAR females displayed higher antibody titers, lower BW4, and matured at older ages than those from LAS and LAR (P < 0.05). Correlations between BW at 4 wk and antibody titers were different between the selected lines, being positive in line LAS and negative in line HAS. Quadratic regression models fit well with antibody titers, BW4, and PNE, with limiting values for these traits calculated based on regression curves. For line HAS, plots showed that an increased tendency of antibody titers was followed by decreased BW4 and increased PNE. For line LAS, however, antibody titers and BW4 decreased in parallel while PNE increased. It appears that at the phenotypic level there was a resource balance between immune response, growth, and reproductive traits, which during long-term selection, individuals altered their dynamic of resource allocations to satisfy certain needs.

Effect of selection for resistance and susceptibility to viral diseases on concentrations of dopamine and immunological parameters in six-week-old chickens

White Leghorn chickens were inbred respectively from their parent lines, which were diversely selected for resistance (line 6(3)) or susceptibility (lines 7(2) and 15I(5)) to Marek's disease and lymphoid leukosis. The differences in disease resistance may have been due to differential regulation of immune and neuroendocrine homeostasis. At 5 wk of age, chickens from the same line were randomly assigned to cages at 4 birds per cage. Blood samples were collected from the chickens at 6 wk of age (n = 10/line). Subsets of T lymphocytes (CD4+ and CD8+) and B cells were measured using flow cytometry. Concentrations of plasma IgG and dopamine were quantified with ELISA and HPLC assay, respectively. Line 6(3) chickens had a higher percentage of CD8+ cells but not CD4+ cells than the chickens of the lines 7(2) and 15I(5) (P < 0.01). In contrast, both lines 7(2) and 15I(5) had a greater percentage of B cells (P < 0.01). The concentrations of plasma IgG and dopamine were also regulated differently among the lines; both were in an order of 7(2) > 15I(5) > 6(3) (P < 0.05 and P < 0.01, respectively). These results suggested that genetic selection for disease resistance also directly or indirectly modified the corresponding genetic components that govern the immune and neuroendocrine systems. The genetic lines of chickens may be used as animal models for investigation of the cellular mechanisms of genetic-environmental interactions on disease resistance.

Memory antibody responses of broiler and leghorn chickens as influenced by dietary vitamin E and route of sheep red blood cell administration

Influences of dietary levels of vitamin E fed to hens and their progeny, and routes of SRBC inoculation on antibody responses of diverse populations of chickens were studied. Populations were a commercial broiler sire line (C), 2 commercial broiler dam lines (A and B), and Leghorn lines selected for high (H) or low (L) antibody response to SRBC. Dams from lines A and B were fed diets supplemented with either 10 or 300 IU/kg of vitamin E, whereas dams from lines H and L received only the diet with 10 IU of vitamin E/kg. Progeny from matings of C males with A and B females as well as H and L females mated to males from their respective lines were hatched on the same day and fed diets supplemented with either 10 or 300 IU/kg of vitamin E. Breeders were the same age and eggs were incubated in the same machine. Chicks were inoculated on d 14 intravenously with 0.1 mL of a 0.5% suspension of SRBC or intramuscularly with 0.1 mL of a 25% suspension of SRBC. Antibody response was measured 6 and 14 d later. Chicks received a booster i.m. inoculation of 0.1 mL of 25% SRBC on d 28. Titers were again measured 6 and 14 d later. Level of vitamin E fed to dams did not affect progeny BW or plasma vitamin E levels. Although titers were higher following i.v. than i.m. inoculation, the degree of difference varied among stocks. Dietary vitamin E level interacted with inoculation route with a greater response to the higher than lower level of vitamin E for i.v., but there was no difference for i.m. There were stock x level of vitamin E and stock x route of inoculation interactions for secondary responses to SRBC inoculation. Stock rankings after the first inoculation were not predictive of the rankings after the second inoculation. The 30-fold increase in dietary level of vitamin E resulted in >12-fold differences in plasma levels of vitamin E. Overall, there was a stock-dependent influence of dietary vitamin E on growth and humoral antibody response.

A comparison of the immune response of a 2001 commercial broiler with a 1957 randombred broiler strain when fed representative 1957 and 2001 broiler diets

Immunocompetence of the 2001 Ross 308 broiler strain and the 1957 Athens Canadian Randombred Control (ACRBC) strain was compared when they were given diets representative of those that were being used in 1957 and 2001. Antibody response against SRBC, in vivo lymphoproliferation against Phytohemagglutinin-P (PHA-P), and inflammatory and phagocytic responses of the macrophages were measured. The Ross 308 strain on the 2001 diet had higher BW at 24 d of age (P = 0.0001), whereas the ACRBC had greater lymphoid organ weights (except thymus) relative to BW (P < or = 0.003). The ACRBC strain showed greater antibody responses against SRBC than the 2001 Ross 308 birds for much of the trial (P < or = 0.0362). However, the Ross 308 broilers had greater PHA-P-induced toe-web swelling response (P < or = 0.0129). Inflammatory exudate cell numbers were higher in the Ross 308 broilers than in the ACRBC birds (P = 0.0261). The percentage of macrophages that phagocytized SRBC was comparable between the two strains, but the number of SRBC phagocytized by individual macrophages was higher (P = 0.0122) in the Ross 308 broiler than in the ACRBC chickens. Nitrite production by macrophages following lipopolysacharide stimulation was comparable between the two strains. Interactions of diet, strain, and sex were inconsistent among all parameters tested. In conclusion, the current study suggested that genetic selection for improved broiler performance has resulted in a decrease in the adaptive arm of the immune response but an increase in the cell-mediated and inflammatory responses.

Effect of genetic selection for group productivity and longevity on immunological and hematological parameters of chickens

A line of White Leghorn chickens was selected for high group productivity and longevity resulting in improved survival and feather score as well as reduced cannibalism and flightiness. Improvements in survival might have also been due to improved immunity. The present study was designed to test the hypothesis that selection for high (HGPS) and low (LGPS) group productivity and survivability also altered immune and hematological parameters. The LGPS line was an intense reverse selected line of the HGPS line at the eighth generation of development. Hens were randomly assigned to individual cages at 17 wk of age. Blood samples were collected from the hens at 21 wk of age. Subsets of T lymphocytes (CD4+, CD8+, and gammadelta cells) were measured using flow cytometry. Concentrations of plasma IgG were quantified with western blot analysis and immunoprecipitation assay. Hematological parameters were collected from blood smears. The HGPS hens had significantly higher percentages of blood lymphocytes and CD4+:CD8+ ratios of circulating T cells (P < 0.01) and tended to have more, but not significantly, gammadelta T cells (P = 0.07) than the LGPS hens. In contrast, the LGPS hens exhibited eosinophilia and heterophilia and greater heterophil:lymphocyte ratios (P < 0.01). The concentrations of plasma IgG were also significantly higher in the LGPS hens (P < 0.01). These results suggest that genetic selection for group productivity and longevity also alters the immunological and hematological systems of hens. The line difference in regulation of T cells, leukocytes, and production of IgG may suggest that different genes or modes of gene action are involved.

Effect of route of inoculation on humoral immune response of White Leghorn chickens selected for high or low antibody response to sheep red blood cells

Effects of route of SRBC inoculation and antigen dosage on primary and secondary antibody response of White Leghorn lines selected for high (HA) or low (LA) 5-d antibody response to a single i.v. inoculation with 0.1 mL of a 0.25% suspension of SRBC were studied in two trials. In the first trial, chicks from parents of generation S24 of each line were randomly assigned to one of four treatments. At 35 d of age, they were inoculated into the brachial vein with 0.1 mL of 0.25% suspension of SRBC or into the breast muscle with 0.1 mL of 0.25, 2.50, or 25.00% SRBC. Plasma SRBC antibody was measured 3, 6, 10, and 20 d later. In the second trial, chicks from parents of generation S25 of each line were randomly assigned to treatment groups. At 28 d of age they were inoculated with 0.1 mL of 0.25% SRBC into the brachial vein, 0.1 mL of 25.00% SRBC into the thigh (T-L) or breast muscle (B-L), or 0.5 mL of 25.00% SRBC into the thigh (T-H) or breast muscle (B-H). Twenty-one days later, chicks (except five per group) were given a booster inoculation of 0.1 mL of 25.00% SRBC into the thigh muscle. Six and 10 d after each inoculation, plasma SRBC antibody, IgG, and IgM titers were measured. The SRBC antibody titers after primary i.v. inoculation with SRBC were always higher for HA than LA chicks. When inoculations were i.m., differences between lines varied with dosage. Low dosages inoculated into the breast failed to induce line differences consistently, whereas at higher dosages, titers were greater for HA than LA chicks regardless of inoculation site. For Line LA, inoculation into the thigh elicited higher titers than inoculations into the breast. Antibody titers to the booster inoculation of SRBC were similar for the lines.

Immunomodulatory effects of indomethacin and prostaglandin E2 on primary and secondary antibody response in growing layer hens

Effects of prostaglandin E2 (PGE2) and indomethacin, an inhibitor of PGE2 oxygenase, on primary and secondary antibody (Ab) responses to Mycobacterium butyricum protein or keyhole limpet hemocyanin (KLH) were studied in growing layer hens. Immunizations at 35 and 70 d of age were accompanied by immunomodulating treatments with PGE2, indomethacin, or PBS. In addition, we studied effects of various doses of indomethacin and PGE2 on mitogen-induced T-cell proliferation in vitro. Secondary Ab responses to KLH were enhanced by administration of indomethacin at secondary immunization and, to a lesser extent, by PGE2 administration at secondary immunization. Primary Ab responses to M. butyricum tended to decrease by administration of either PGE2 or indomethacin. Secondary Ab responses to M. butyricum were affected by administration of both PGE2 and indomethacin at primary immunization. Prostaglandin E2 increased phytohemagglutinin (PHA)-induced lymphocyte proliferation. Indomethacin decreased Concanavalin A (ConA)- and PHA-induced lymphocyte proliferation. The net effect of indomethacin on the Ab response could not be explained by inhibition of PGE2 oxygenase only. Our data rather suggest an inhibition by indomethacin of other immunosuppressing factors derived from arachidonic acid. We concluded that polyunsaturated fatty acid-derived products might especially affect secondary antibody responsiveness. This finding may depend on inhibition or enhancement of T-cell responsiveness. Consequently, immunomodulation by dietary polyunsaturated fatty acids may have profound effects at secondary rather than at primary exposure to pathogens.

Antibody responses to different dosages of sheep red blood cells in lines of chickens selected for high and low antibody response to sheep red blood cells

Temporal patterns of SRBC antibody response after primary and secondary inoculations were measured in White Leghorn males from lines selected 24 generations for high (HA) or low (LA) 5-d antibody titers to an i.v. inoculation with 0.1 mL of a 0.25% suspension of SRBC. Primary i.v. inoculations were administered at 50 d of age as 0.1 mL of either 0.025 or 0.25% suspension of SRBC. Antibody levels of SRBC were measured 3, 5, 7, 9, 11, 13, and 20 d after inoculation. Also, IgG levels were measured on samples obtained 3, 7, 13, and 20 d after inoculation. At 70 d of age, half of the cockerels in each line-dosage subclass were given a booster inoculation of 0.1 mL of 0.25% SRBC. The SRBC antibody was measured 3, 6, 9, and 13 d later in chicks both receiving and not receiving the second inoculation. Patterns of antibody response to SRBC dosage differed according to line, resulting in interactions of line by dosage by day. Concentrations of IgG were greater for Line HA than for LA at 7 and 11 d after inoculation with SRBC but not at 3 and 20 d. Antibody responses to the booster inoculation differed between lines with a dosage effect present for LA but not for HA chicks. The greater anamnestic response observed in LA than in HA chicks is explained in the context of the resource allocation paradigm.