Genetic aspects of antibody responses in chickens to different classes of antigens

Genetic Variation in Natural and Induced Antibody Responses in Layer Chickens

Selection of livestock for disease resistance is challenging due to the difficulty in obtaining reliable phenotypes. Antibodies are immunological molecules that provide direct and indirect defenses against infection and link the activities of both the innate and adaptive compartments of the immune system. As a result, antibodies have been used as a trait in selection for immune defense. The goal of this study was to identify genomic regions associated with natural and induced antibodies in chickens using low-pass sequencing. Enzyme-linked immunosorbent assays were used to quantify innate (natural) antibodies binding KLH, OVA, and PHA and induced (adaptive) antibodies binding IBD, IBV, NDV, and REO. We collected plasma from four White Leghorn (WL), two White Plymouth Rock (WPR), and two Rhode Island Red (RIR) lines. Samples numbers ranged between 198 and 785 per breed. GWAS was performed within breed on data pre-adjusted for Line-Hatch-Sex effects using GCTA. A threshold of p = 10-6 was used to select genes for downstream annotation and enrichment analysis with SNPEff and Panther. Significant enrichment was found for the defense/immunity protein, immunoglobulin receptor superfamily, and the antimicrobial response protein in RIR; and the immunoglobulin receptor superfamily, defense/immunity protein, and protein modifying enzyme in WL. However, none were present in WPR, but some of the selected SNP were annotated in immune pathways. This study provides new insights regarding the genetics of the antibody response in layer chickens.

Protective effect of Enterococcus faecium J96, a potential probiotic strain, on chicks infected with Salmonella Pullorum

Enterococcus faecium J96 was isolated from a healthy free-range chicken and it inhibited Salmonella Pullorum, in vitro, due to its lactic acid and bacteriocin production. In vivo assays were carried out with 30-h-old broiler chicks. The lactic acid bacteria (approximately 1 x 10(9) cells per chick) were orally administered as preventive and as therapeutic treatments. In the first case they were given to the chicks twice a day for 3 consecutive days. In the second case the lactic bacteria were administered in the same way after a 24-h challenge by Salmonella Pullorum (in both instances the salmonella dose was 1 x 10(5) cells per chick). Cecal contents, liver, and spleens were analyzed and liver and spleen fragments were also fixed in formaldehyde (pH 7.00) in order to determine salmonella translocation. The chickens that were preventively treated with E. faecium J96 survived the Salmonella Pullorum challenge. Those that were infected on the first day and then inoculated with lactic bacteria died 4 days later. Salmonellae were isolated from their livers and spleens. From these results we may conclude that E. faecium J96 can protect newly hatched chicks from Salmonella Pullorum infection but cannot act as a good therapeutic agent.

Antibody response to sheep erythrocytes in Indian native vis-à-vis imported breeds of chickens

1. A total of 433 birds (7 weeks old) of both sexes belonging to Indian native breeds, including, Aseel, Kadakanath, Naked Neck and Frizzle fowl along with the imported breeds Dahlem Red, White Leghorn, Synthetic dam line broiler (SDL) and Naked Neck broiler were utilised to test the primary antibody response to sheep erythrocytes by haemagglutination test. The effect of genotype (breed), sex and their interactions on antibody response were also studied. 2. The results revealed the presence of natural antibodies in all groups under study. 3. All groups except broilers showed the highest HA titre on day 5 post immunisation, which gradually declined until the end of the experiment (19th day post immunisation). In broilers, the peak HA titre was observed on day 12. 4. Dahlem Red showed the highest response throughout. The lowest antibody response was recorded for broilers except on day 19 post immunisation when it exceeded the White Leghorn value. 5. Amongst the native Indian breeds, the Naked neck had the highest titre on day 5 post immunisation but the Aseel titre was highest on days 12 and 19. 6. Males tended to have higher titres than females in Aseel, Kadakanath, Naked Neck, White Leghorn and Naked Neck broilers whereas Frizzle, Dahlem Red and SDL broilers showed the converse. 7. Statistical analysis revealed significant variation in HA response among the various genetic groups on different days post immunisation. The apparent differences between sexes were not significant. However, interactions between breed and sex were significant on day 5 and 19 post immunisation.

Genetic studies on primary antibody response to sheep erythrocytes in guinea fowl

1. The primary antibody response to sheep erythrocytes was determined by haemagglutination test in guinea fowl. The effects of various genetic and non-genetic factors on immune response to sheep RBCs in guinea fowl were also estimated. 2. The immune response to sheep RBCs was normally distributed in guinea fowl with mean titre at 1.534 +/- 0.014. 3. In guinea fowl, effects on titre values of sire and variety (feather colour) were significant whereas sex and sex x variety interaction effects were non-significant. 4. The estimate of heritability for immune response to sheep RBCs in guinea fowl was 0.35 +/- 0.17.

Immune and physiological responses of turkeys with green-liver osteomyelitis complex

A study of field turkeys was undertaken in order to determine the involvement of relative immunological differences in the etiology of turkey osteomyelitis complex (TOC). Lame and normal turkeys were sampled from commercial flocks just prior to processing in two separate trials. After testing for functions of both humoral and cellular immunity, the turkeys were necropsied and examined for lesions of TOC. There were significantly higher relative spleen and over weights and significantly lower body weights and relative bursal weights in birds with TOC. The birds with TOC had lower response to phytohemagglutinin-P in both in vivo and in vitro tests as well as lower circulating lymphocyte counts and higher monocyte, heterophil, and total white blood cell counts. There was a significantly higher antibody response to sheep red blood cells in turkeys with TOC, whereas antibody response to Salmonella pullorum antigen was not different. There were no significant differences in the percentages of mononuclear cells or heterophils able to phagocytize bacteria or latex particles, or kill bacteria; however, the heterophils from turkeys with TOC lesions did phagocytize significantly fewer latex particles per cell than did those of the healthy turkeys. Total serum protein, uric acid, and blood urea nitrogen levels were higher in birds with TOC, whereas hemoglobin, iron, alkaline phosphatase, and gamma-glutamyl-transferase levels were lower. Although many of the differences in birds with TOC could be caused by the normal host reaction to infection, further study may reveal innate differences that contribute to susceptibility to TOC.

Gordon Memorial Lecture. Stress, strains and resistance

1. Stress describes the bird's defence mechanisms and a stressor is the situation that elicits the defence response. 2. As the environment can be viewed as a composite of interacting stressors, the bird's success in coping with its environment depends on the severity of the stressors and the physiological ability to respond properly and thus maintain homeostasis. 3. The neural, endocrine and more recently immune systems are considered to be integrators of the stress response. Although stress responses may be necessary for survival in wild bird populations, they are often detrimental to efficient growth, skeletal integrity and disease resistance in domesticated fowl. 4. Stress responses are modified by the genetic components.

Genetic analysis of antibody responses of turkeys to Newcastle disease virus and Pasteurella multocida vaccines

Heritability (h2) of 16-wk BW and primary and secondary antibody responses and genetic and phenotypic correlations among these traits were estimated for 931 male and female turkeys vaccinated with Newcastle disease virus (NDV) and Pasteurella multocida. Turkeys from a line selected for 22 or 23 generations for increased 16-wk BW were vaccinated at 6 and 12 wk of age with blood samples collected 3 wk postvaccination. Antibody titers were determined using an ELISA method and transformed to log(e) for analysis. Heritability estimates for primary and secondary antibody responses to NDV were .380 +/- .070 (SE) and .296 +/- .063, respectively. For primary and secondary antibody responses to P. multocida, h2 estimates were .458 +/- .075 and .333 +/- .066, respectively. Heritability estimate for 16-wk BW was .404 +/- .071. The genetic correlation between primary and secondary antibody responses to NDV was .491 +/- .150. There was no genetic correlation between primary and secondary antibody responses to P. multocida. Although the genetic correlation between primary antibody responses to NDV and P. multocida was .292 +/- .159, the genetic correlation between secondary responses to the two antigens did not differ from zero. There were no genetic correlations between antibody responses and 16-wk BW. Similar results were observed for phenotypic correlations. Based on heritability and genetic correlation estimates, it would be possible to improve antibody responses to either NDV or P. multocida singularly; however, to improve antibody responses to both antigens, selection would have to be applied for each antigen.

Evaluation of resistance of four strains of commercial laying hens to experimental infection with Salmonella enteritidis phage type eight

Four different strains of White Leghorn hens were orally infected with 1 x 10(8) cfu of Salmonella enteritidis phage Type 8 per bird. The birds were monitored for 10 wk postinfection for colonization of internal organs, fecal shedding of S. enteritidis, and the production of S. enteritidis-contaminated eggs. There was no difference among the four hen strains in regards to the probability of S. enteritidis isolation from liver and spleen, ovary, and cecal tissue within the first 30 d postinfection. However, during the first 14 d postinfection, S. enteritidis organisms were isolated in significantly higher rates from eggs and fecal samples of Strain A than from samples obtained from the other three hen strains. Results suggest that there may be inherent differences between strains of laying hens with regard to their response to infection with S. enteritidis.

Evaluation of the humoral immune response to different antigens in Arkansas Regressor and Progressor chickens

Arkansas Regressor and Progressor chickens were re-evaluated for their immune response to different antigens. Chickens received i.v. injection of either SRBC (10 birds per line) or Salmonella pullorum (SP; 10 birds per line) at 7 wk of age, and sera were collected at 6, 13, and 20 d postimmunization. A third group of birds (10 birds per line) received and i.m. injection of GAT emulsion at 7 and 12 wk of age, and sera were collected at 10 and 14 wk of age. There were significant differences between the two lines in their humoral immunity to SRBC, SP, and GAT. Such results suggest genetic control of humoral immunity to these antigens in these lines. It is unknown whether humoral immunity to these antigens is correlated to regression of tumors induced by Rous sarcoma virus.

Antibody responses to combinations of antigens in white Leghorn chickens of different background genomes and major histocompatibility complex genotypes

Antibody responses in chickens to SRBC, Newcastle disease (NDV), and Brucella abortus (BA) were compared when given singly or in combination. Chickens used in the present experiment originated from a cross and then backcrossing of White Leghorn populations that had been selected for high (HA) or low (LA) antibody response to SRBC antigens. The populations used in the current study were segregating for MHC haplotypes B13 and B21. The experiment had a 2 x 3 x 6 factorial arrangement of treatments (two background genomes: HA and LA; three MHC haplotypes: B13B13, B13B21, and B21B21; and six antigen treatments: SRBC, NDV, or BA only, SRBC plus NDV, SRBC plus BA, and NDV plus BA). Antigens were administered either i.v. (SRBC) or i.m. (NDV and BA) when chicks were 42 days of age. Blood was obtained 27 days later (69 days of age) for antibody determinations. A significant background genome by MHC haplotype interaction for BA antibodies was due to relatively high titers in Line HA chickens of MHC genotypes B13B13 and B13B21. Background genome by MHC genotype interactions were not significant for SRBC or NDV antibodies. Antibody titers to SRBC were higher in background genome HA than LA, and similar among MHC genotypes. Antibodies to NDV were lower in chickens of MHC genotype B21B21, but there were no differences due to background genome. For each of the three antigens, antibody responses were highest when administered singly rather than in combination. Antibody titers were lower for SRBC when given with BA, and for BA titers when given with NDV.(ABSTRACT TRUNCATED AT 250 WORDS)

Progeny performance when dams and chicks are fed supplemental zinc

Three consecutive trials involving approximately 700 to 800 broilers (0 to 28 days) were conducted to examine effects on growth and immunity of chicks after supplementing dams with inorganic Zn versus organic Zn. Offspring from hens fed a basal diet (72 mg Zn/kg) or diets with 152 mg Zn/kg supplemented with ZnO or organic Zn-Met were randomized across four battery brooders. Chicks were fed a starter diet without supplemental Zn containing 100 mg Zn/kg or diets supplemented with 40 mg/kg Zn from ZnO and DL-Met or Zn-Met containing 140 mg Zn/kg. No differences among treatments (P greater than .05) were found in feed conversion or average BW. Supplemental Zn-Met in hen diet increased (P less than .06) cellular immune response in progeny. Embryonic bone weights were higher (P less than .05) in progeny when dams were fed Zn-Met. Zinc as Zn-Met in diets of dams and progeny enhanced primary antibody titers to Salmonella pullorum antigen.

Research note: effects of age and immunization interval on the anamnestic response to T-cell-dependent and T-cell-independent antigens in chickens

Measurement of a humoral anamnestic response is a common procedure used to evaluate immunological competence. The purposes of the present study were to determine the optimum time period between primary and secondary immunizations needed to obtain the maximum antibody titer and to determine whether this interval differs with the age of the chicken or with the type of inducing antigen. The anamnestic responses of birds of two ages to a T-cell-dependent antigen (SRBC) and to a T-cell-independent antigen (Brucella abortus, BA) were evaluated. Birds of 4 wk or 6 mo of age were injected i.v. with either BA or SRBC, and a secondary injection was given 2, 4, 6, or 8 wk later. Agglutination titers for total and mercaptoethanol (ME)-resistant antibodies were determined from serum samples collected at 3, 6, and 9 days postsecondary immunization. Generally, titers were highest at 6 days postsecondary immunization. For both antigens, the chick total antibody levels at Day 6 postsecondary immunization were higher at 4-, 6-, and 8-wk immunization intervals than at 2-wk intervals; adult titers were independent of immunization interval. There was an interaction between age of birds and type of antigen.

Estimates of quantitative genetic parameters of immunological traits in the chicken

Three in vivo assays were used to measure the immunocompetence of chickens in two generations of a selection experiment. The obtained data were used to estimate the variance components for sire and dam for antibody production to Pasteurella multocida and Mycoplasma gallisepticum vaccines, for T-cell-mediated immunity evaluated by a phytohemagglutinin wing web assay, and for clearance of foreign particles from the circulatory system. Heritabilities of and genetic correlations among these immunological traits were calculated from the sire variance components. Heritability estimates of the immunological traits based on the sire component of variance ranged from .06 to .53, and genetic correlations among immunological traits were generally negative.

Antibody response to Newcastle disease virus and Pasteurella multocida of two strains of turkeys

The primary and secondary response to Newcastle disease virus (NCDV) and Pasteurella multocida (PM) of two turkey lines were studied following vaccinations with either NCDV or PM alone, or in combination. The two turkey strains were 1) a randombred control line (RBC1) and 2) a subline (E) of Line RBC1 selected 27 generations for increased egg production. This study consisted of five trials. Each trial represented a separate hatch. In Trial 1, poults of each line were subcutaneously vaccinated with a 1-mL dilution of B1 type LaSota strain NCDV vaccine. In Trial 2, poults of each line were wing-web vaccinated with the M-9 strain of PM Heddleston Type 3 x 4 cross at 6 and 10 wk of age. In Trial 3, poults of each line were subcutaneously vaccinated on the back of the neck with 1 mL of inactivated NCDV at 6 and 10 wk of age. In Trial 4, .5 mL of a PM bacterin containing Types 1, 3, and 4 in an oil emulsion was used to subcutaneously vaccinate poults of each line at 6 and 10 wk of age. In Trial 5, poults of each line were simultaneously vaccinated with inactivated NCDV (subcutaneously) and a PM bacterin (intramuscularly) at 6 and 10 wk of age. Line RBC1 had significantly (P less than .01) higher maternal antibodies to Newcastle disease at 3 wk of age than those of Line E. The RBC1 line generally had significantly higher levels of antibodies than Line E in response to vaccination for both NCDV and PM when administered singularly or in combination.

Genetic analysis of immunocompetence measures in a White Leghorn chicken line

Immunocompetence of the Iowa State University S1 White Leghorn chicken line was studied. This line was divided into eight sublines based upon erythrocyte antigen B (Ea-B) allele (B1B1 or B19B19), antibody response to glutamic acid60-alanine30-tyrosine10 (GAT) (high or low), and response to Rous sarcoma virus-induced tumors (progression or regression). Antibody responses to Pasteurella multocida (PM), Mycoplasma gallisepticum (MG), and infectious bursal disease virus vaccines were evaluated by enzyme-linked immunosorbent assay. Phagocytic activity and T cell-mediated response were measured by carbon clearance and phytohemagglutinin (PHA) injection assays, respectively. Significant haplotype (subline) differences and sire family differences were observed in all three measurements. Significant sex differences were observed in phagocytic activity and T cell-mediated responses. Haplotypes with high antibody responses to GAT had significantly higher antibody titers to PM and MG vaccines than haplotypes with low antibody responses. Significant positive correlations were observed between antibody levels to the two vaccines. A significant negative correlation was seen between phagocytic activity and T cell-mediated response of females. The data suggest that the total immunocompetence profile of an individual must be considered to select for optimum immune responsiveness.

Genetic associations of body weight and immune response with the major histocompatibility complex in White Leghorn chicks

Survival, body weight, and humoral immune response to sheep red blood cells (SRBC) were measured in 256 chicks of the Iowa State University S1 Leghorn line. The chicks were produced from breeders selected for serological Ea-B blood type (B1 or B19), high or low humoral immune response to the amino acid polymer, glutamic acid-alanine-tyrosine (Ir-GAT), and response to Rous sarcoma virus-induced (RSV) tumors (progression or regression). Chicks were hatched from sublines representing all eight triple homozygous genotypes. Survival was significantly (P less than .01) associated with Ir-GAT, but not with Ea-B or RSV response. Body weight was affected by Ea-B, Ir-GAT, and the interaction between Ea-B and Ir-GAT, but not by interaction with RSV response. The SRBC antibody titer was affected by the interaction of Ea-B and Ir-GAT. The SRBC antibody titer was also lowest in the B19 low group. There were positive significant correlations (.21 to .31) between SRBC antibody titer and body weights at all ages except hatch in the Ir-GAT low group, but there were no significant correlations between SRBC antibody titer and body weights in the Ir-GAT high group. In this population of White Leghorn chicks, the heritabilities of body weight ranged from .43 to .27 for weights at 2 to 6 wk of age, and the heritability of SRBC antibody titer at 4 wk was .34 +/- .25.

Immunocompetences and Marek's disease resistance in three pairs of chicken lines selected for different immunological characters

Three pairs of chicken lines selected for high (H) and low (L) graft vs. host reaction (GVHR) competences, serum immunoglobulin G (IgG) levels, and antibody responses to Leucocytozoon caulleryi were examined for their immunocompetences and Marek's disease (MD) resistance. The GVHR-H and GVHR-L lines were further divided into two sublines according to their major histocompatibility B genotype. Immune responses to sheep erythrocytes (SRBC), bovine serum albumin (BSA), and a lipopolysaccharide (LPS) were compared between the high and low lines of each pair of selected lines. Significant differences were found in responses to SRBC and LPS in IgG-selected lines and in response to BSA in Leucocytozoon-selected lines. In all three instances antibody titers of the H line were higher than those of the L line. The GVHR competence expressed by the splenomegaly index (SI) was also significantly different between the H and L lines of all three selected-line pairs. The SI values in the GVHR-selected and IgG-selected lines were higher in the H line than in the L line, whereas those in the Leucocytozoon-selected lines were lower in the H line. Differences in MD incidence and in MD mortality were found between the GVHR-selected B11B11 subline and the IgG-selected lines. In both instances the L line was more resistant to MD than the H line.