Antibody response to sheep red blood cells in major histocompatibility (B) complex aneuploid line of chickens

The effects of supplementation of Withania coagulans and α-tocopherol acetate in diets containing oxidised oil on growth performance, immune response and antioxidant indices in broiler chickens

This experiment was designed to study the effects of a hydroalcoholic fruit extract from Withania coagulans (WC) and α-tocopherol acetate (α-Toc) in diets containing oxidised oil on growth performance, immune response and antioxidant indices of broiler chickens. The experiment was arranged 2 × 3 × 2 factorial comprising the oxidised oil (0% and 2% diet), WC (0, 100 and 200 mg/kg diet) and α-Toc (0 and 200 mg/kg diet). A total of 600 1-day-old male broiler chickens of the Ross strain were randomly allocated to 12 treatments with 5 replicates of 10 birds each. On day 42, one bird from each replicate was sacrified to measure the lymphoid organ weights, intestinal morphometric characteristics, and malondialdehyde content in the thigh meat. Dietary inclusion of oxidised oil significantly reduced the body weight gain in birds receiving no dietary WC (p < 0.05). In contrast, dietary supplementation of WC at 100 mg/kg diet in birds fed with the diets lacking in WC and oxidised oil resulted in significant increase in body weight gain (p < 0.05). Dietary supplementation of WC significantly increased the total anti-sheep red blood cell titre (p < 0.01). The birds fed with the dietary oxidised oil revealed significantly higher values of malondialdehyde and lower glutathione peroxidase and superoxide dismutase activities (p < 0.05). Feeding diets containing WC resulted in a significant decrease in malondialdehyde content in thigh meat while conversely, increased the glutathione peroxidase and superoxide dismutase activities (p < 0.05). The findings indicated that the dietary inclusion of WC could be recommended as a potent alternative to synthetic compounds in order to improve broilers performance, immunity and meat quality under oxidative stress conditions.

Evaluation of neurobehavioral abnormalities and immunotoxicity in response to oral imidacloprid exposure in domestic chickens (Gallus gallus domesticus)

Domestic chickens (Gallus gallus domesticus) were exposed to imidacloprid by gavage once daily for 7 consecutive days at 0, 0.03, 0.34, 3.42, 10.25, and 15.5 mg/kg/day (n = 20 per group; 5 6-week-old males, 5 6-week-old females, 5 9-week-old males, and 5 9-week-old females). The severity and duration of neurobehavioral abnormalities were recorded. Components of the innate and adaptive immune system were assessed with 7 standard functional assays. Temporary neurobehavioral abnormalities were observed in a dose-dependent manner, including muscle tremors, ataxia, and depressed mentation. Based upon mean clinical severity scores, the no observed adverse effect level (NOAEL) was 3.42 mg/kg/day, and the lowest observed adverse effect level (LOAEL) was 10.25 mg/kg/day. The effective dose value for the presence of any neurobehavioral abnormalities in 50% of the test group (ED₅₀) was 4.62 ± 0.98 mg/kg/day. The ED₅₀ for an adjusted score that included both severity and duration of neurobehavioral abnormalities was 11.24 ± 9.33 mg/kg/day. These ED₅₀ values are equivalent to a 1 kg bird ingesting 29 or 70 imidacloprid treated soybean seeds respectively. Immunotoxicity was not documented, possible causes include the assays were insensitive, relevant immune functions were not examined, or imidacloprid is not immunotoxic at this dosing schedule in this species. Neurobehavioral abnormalities were a more sensitive indicator of the sublethal effects of imidacloprid than immunotoxicity.

Effects of dietary selenium and vitamin E on immune response and biological blood parameters of broilers reared under thermoneutral or heat stress conditions

A study was conducted using 360 broiler chickens to evaluate the effects of dietary vitamin E (0, 125 and 250 mg/kg), selenium (Se, 0, 0.5 and 1 mg/kg), or their different combinations on immune response and blood biological parameters of broilers raised under either thermoneutral (TN, 23.9 °C constant) or heat stress (HS, 23.9 to 37 °C cycling) conditions. Humoral immunity was assessed by intravenous injection of 7% sheep red blood cell (SRBC) followed by evaluation of serum for antibody titers in primary and secondary responses. Heterophil to lymphocyte (H/L) ratio also determined as an indicator of stress. Furthermore, at the end of the experiment, birds were bled for determination of some biological parameters. There was a significant reduction in body weight and feed intake, but the feed conversion ratio increased when the birds were exposed to HS (P<0.05). Body weight and feed intake were not influenced significantly by dietary vitamin E and Se (P>0.05), whereas feed conversion was improved significantly by 125 mg/kg vitamin E (P<0.05). The liver and lymphoid organ weights as well as IgM and IgG, antibody titers for primary and secondary antibody responses to SRBC were reduced significantly under HS (P<0.05). Heat stress also resulted in a significant increase in H/L ratio (P<0.05). Dietary vitamin E resulted in improvement of primary and secondary antibody responses both in TN and HS broilers (P<0.05). The HS birds also showed an improved antibody titer in secondary response with high concentration of Se (P<0.05). Vitamin E and Se had interactive effects on anti-SRBC titers; however, no consistent differences were found between dietary levels during the study. The H/L ratio decreased by feeding vitamin E at both levels either under HS or TN conditions (P < 0.05). The serum concentrations of glucose, triglycerides, total cholesterol, and LDL-cholesterol were increased but serum HDL-cholesterol decreased in HS broilers (P<0.05).

Effects of different levels of organic and inorganic chromium on growth performance and immunocompetence of broilers under heat stress

This experiment was carried out to investigate the effects of different levels of organic and inorganic chromium on the performance, immune function and some serum mineral concentrations of broilers under heat stress condition (23.9-37°C cycling). A total of 150 one-day-old broiler chicks according to a completely randomized design were assigned into five treatment groups. Each treatment consisted of three replicates and each replicate contained ten chicks. Chicks were fed on corn-soybean meal basal diets with added different concentrations of chromium (0, 600 and 1,200 μg kg(-1) chromium chloride or 600 and 1,200 μg/kg chromium L-methionine) from 1 to 49 days of age. Humoral immunity was assessed by intravenous injection of 7% sheep red blood cell (SRBC) followed by evaluation of serum for antibody titers in primary and secondary responses. Cell-mediated immunity was assessed by the cutaneous basophil hypersensitivity (CBH) test to phytohemagglutinin (PHA)-P at day 32 and PHA-M at day 48. Heterophil/lymphocyte (H/L) ratio was also measured as a reliable indicator of stress. The body mass, feed intake and conversion ratio were not influenced by dietary chromium (P > 0.05). Dietary supplementation of both organic and inorganic chromium significantly increased primary and secondary antibody responses (P < 0.01), and also improved H/L ratio (P < 0.05), CBH response (P < 0.01) as well as relative weights of thymus (P < 0.05) and spleen (P < 0.01). Both dietary organic and inorganic chromium caused an increase in serum concentrations of Cr and Zn (P < 0.01), but decreased the serum concentration of Cu (P < 0.01). These results suggest that supplemental chromium especially in organic form offers a good management practice to reduce heat stress-related depression in immunocompetence of broiler chicks.

Effects of different levels of vitamin E on growth performance and immune responses of broilers under heat stress

This experiment was undertaken to evaluate the effect of dietary vitamin E on growth performance and immune response of broilers under heat stress (HS). Birds raised in either a thermoneutral (23.9 degrees C constant) or HS (23.9 to 38 degrees C cycling) environment were fed a corn-soybean meal basal diet supplemented with vitamin E at 0, 100, or 200 mg/kg, respectively. Two hundred forty 1-d-old male broiler chicks were randomly assigned to 6 groups; each group had 4 replicates of 10 birds. Humoral immunity was assessed by i.v. injection of 7% SRBC followed by evaluation of serum for antibody titers in primary and secondary responses. Cell-mediated immunity was assessed by using a Sephadex stimulation method to recruit abdominal exudate cells (AEC) to evaluate macrophage phagocytic ability. Body weight and feed intake were not significantly influenced by dietary vitamin E (P>0.05), whereas feed conversion was significantly affected by vitamin E at 100 mg/kg (P<0.05). Heat stress significantly reduced BW, feed intake, and feed conversion (P<0.05). Numbers of AEC, percentage of macrophages in AEC, phagocytic macrophages, and internalized opsonized and unopsonized SRBC were increased by dietary vitamin E (P<0.05). Both primary and secondary antibody responses were significantly increased by dietary vitamin E when birds were exposed to HS (P<0.05). Lymphoid organ weights, antibody responses, incidence of macrophages in AEC, and phagocytic ability of macrophages were all significantly reduced under HS. These results indicated that HS severely reduced growth performance and immune response of broilers, whereas the immune response of broilers could be improved by dietary vitamin E supplementation under HS.

MHC class IIB gene sequences and expression in quails (Coturnix japonica) selected for high and low antibody responses

Two quail lines, H and L, which were developed for high (H) and low (L) antibody production against inactivated Newcastle disease virus antigen, were used to examine differences in the organization, structure and expression of the quail Mhc class IIB genes. Four Coja class IIB genes in the H line and ten Coja class IIB genes in the L line were identified by gene amplification using standard and long-range PCRs and sequencing of the amplified products. RFLP analysis, sequencing and gene mapping revealed that the H line was fixed for a single class IIB haplotype, which we have designated CojaII-02HL- CojaII-01HL. In contrast, evidence was found for two class IIB haplotypes segregating in the L line. Some individuals were found to be homozygous for haplotype CojaII-08L- CojaII-07L and others were found to be heterozygous CojaII-08L- CojaII-07L/ CojaII-02HL- CojaII-01HL. However, expression of CojaII-02HL- CojaII-01HL was not detected in the L line. SRBC immunization induced a measurable antibody response in the serum and a line-specific class IIB gene expression in the peripheral white blood cells. CojaII-01HL was expressed at the highest level in the H line and CojaII-07L in the L line. The expression of the class IIB mRNA reached the highest level at approximately 1 week after the primary antibody response and then declined exponentially. The antibody and class IIB gene expression data obtained in response to SRBC immunization provide further evidence that quails within the L line had reduced immunocompetence compared with those in the H line.

Effects of different levels of zinc on the performance and immunocompetence of broilers under heat stress

Male broilers were used to evaluate the effect of zinc on performance and immune competence during heat stress (HS). Broilers raised in either a thermoneutral (TN, 23.9 degrees C constant) or HS (23.9 to 35 degrees C cycling) environment were fed a low zinc diet (LZ; 34 mg/kg), an adequate zinc diet (AZ; 68 mg/kg), or a supplemental zinc diet (HZ; 181 mg/kg). Humoral immunity was assessed by intravenous injection of 7% SRBC followed by evaluation of serum for antibody titers in primary and secondary responses. Cell-mediated immunity was assessed using a Sephadex stimulation method to recruit abdominal exudate cells (AEC) to evaluate macrophage phagocytic ability. The HS birds consumed 12.5% less feed, gained 24.6% less weight, and had lower feed efficiency when compared to TN birds. Dietary zinc levels did not impact growth performance or plasma zinc concentration. Numbers of AEC, macrophages in AEC, phagocytic macrophages, and internalized opsonized and unopsonized SRBC were increased by HZ. Total, IgM, and IgG antibody titers for primary and secondary responses were significantly increased in birds receiving HZ under TN conditions. Tibia zinc concentration increased with increasing zinc levels but did not change with temperature. Lymphoid organ weights, primary and secondary antibody responses, incidences of macrophages in AEC, phagocytic ability of macrophages, and plasma zinc concentration were all significantly reduced by HS. These results indicate that the immune response of broilers can be influenced by the level of zinc in the diet and by environmental conditions.

Candidate gene promoter polymorphisms and antibody response kinetics in chickens: interferon-gamma, interleukin-2, and immunoglobulin light chain

An F2 population was produced from mating G0 highly inbred (>99%) males of two MHC-congenic Fayoumi lines with G-B1 Leghorn hens. The F2 population was essentially a full-sibship with the F1 sire line reflecting MHC effect. Adult F2 hens (n = 158) were injected twice with SRBC and whole fixed Brucella abortus (BA). Agglutinating antibody titer at 7 d after primary immunization and mean titer of the final three samples (Days 18, 32, and 63 after the second immunization) were used as parameters for primary and equilibrium phases, respectively. Secondary phase parameters of minimum (Ymin), maximum titers (Ymax) and time needed to achieve minimum (Tmin) and maximum (Tmax) titers were estimated from seven postsecondary titers with a nonlinear regression model. Three candidate genes, interferon-gamma (IFN-gamma), interleukin-2 (IL-2), and immunoglobulin G light chain (IgL) were studied. Primers for the promoter regions were designed from EMBL chicken genomic sequences. Polymorphisms between parental lines were detected by direct sequencing. Polymerase chain reaction-restriction fragment length polymorphism methods were then developed to directly detect the polymorphism. There were significant main effects (P < 0.05, general linear model analysis) of IFN-gamma polymorphism on Ymax of BA antibody and interaction of IFN-gamma by IgL on primary antibody response to SRBC and BA, and on Tmin and Ymin of antibody response to SRBC in F2 offspring of M5.1 grandsires. There were significant main effects of IFN-gamma polymorphism on Tmax of BA and interaction of IFN-gamma by IL-2 on Ymin to SRBC in F2 offspring of M15.2 grandsires. The results suggest that IFN-gamma genes play an important role in chicken primary and secondary antibody response to SRBC and BA antigens, and there exists interaction among genes for antibody production.

Genetic line and major histocompatibility complex effects on primary and secondary antibody responses to T-dependent and T-independent antigens

The effects of MHC and nonMHC (background) genetics on the kinetics of primary and secondary antibody responses to T-cell-dependent (SRBC) and T-cell-independent [Brucella abortus (BA)] antigens were investigated. Eight genetic groups were represented, with four homozygous MHC haplotypes [B1-IrGATlow (IrGAT = immune response to GAT locus); B1-IrGAThigh; B19-Ir-GATlow; B19-IrGAThigh] on two genetic backgrounds, the S1 and G lines. Birds were injected simultaneously with BA and SRBC at 4 and 7 wk of age, and blood samples were taken weekly from 4 to 10 wk of age for measurement of total agglutinating serum antibody levels. A quadratic equation and its first derivative were computed for each bird to approximate individual curve parameters: y max, the maximum titer; t max, the time required to achieve y max; and c coefficient, the rate of decline in the titer. Curve parameters of birds from different lines were analyzed separately by using the General Linear Model procedure. A second analysis that included line effect evaluated the nonMHC gene effects and their interactions with erythrocyte antigen B locus (Ea-B) or IrGAT. In the S1 line, there was an interaction (P < 0.05) between MHC haplotypes and sex for primary response to BA. In contrast, there were no significant main effects nor interactions in the G line background for primary and secondary responses to BA and SRBC. There was an effect (P < 0.05) of line background on y max for primary BA and for secondary SRBC responses. A positive correlation (P < 0.05) was found between the c coefficients of BA and SRBC secondary responses, suggesting that the rate of decline in the secondary response is similar between these T-dependent and T-independent responses. The overall results of this study indicate complex interactions between specific MHC alleles and the nonMHC background of the lines in which they are studied.

Major histocompatibility complex (MHC) related cDNA probes associated with antibody response in meat-type chickens

The major histocompatibility complex (MHC) region was examined as a set of candidate genes for association between DNA markers and antibody response. Intercross F2 families of chickens were generated from a cross between high (HC) and low (LC) Escherichia coli(i) antibody lines. Restriction fragment length polymorphism (RFLP) analysis was conducted by using three MHC-related cDNA probes: chicken MHC class IV (B-G), chicken MHC class I (B-F), and human MHC-linked Tap2. Association between RFLP bands and three antibody response traits (E. coli, sheep red blood cells and Newcastle disease virus) were determined by two methods: by statistically analyzing each band separately and also by analyzing all bands obtained from the three probes by using multiple regression analysis to account for the multiple comparisons. The MHC class IV probe was the highest in polymorphisms but had the lowest number of bands associated with antibody response. The MHC class I probe yielded 15 polymorphic bands of which four exhibited association with antibody response traits. The Tap2 probe yielded 20 different RFLP bands of which five were associated with antibody production. Some Tap2 bands were associated with multiple antibody response traits. The multiband analysis of the three probes' bands revealed more significant effects than the analysis of each band separately. This study illustrates the efficacy of using multiple MHC region probes as candidate markers for quantitative trait loci (QTLs) controlling antibody response in chickens.

Application of a nonlinear regression function to evaluate the kinetics of antibody response to vaccines in chicken lines divergently selected for multitrait immune response

To evaluate the kinetics of immune response to vaccines in chickens, antibody response curves were approximated to the observed antibody ratios by using a nonlinear regression function. New parameters, the curve maximum (ymax) and the time of the maximum (tmax), were calculated. The method was applied to analyze the kinetics of the serum antibody response to Mycoplasma gallisepticum (MG) and Pasteurella multocida (PM) vaccines in White Leghorn lines selected, in replicate, for 10 generations for high (High) and low (Low) multitrait immune response. Chicks were immunized at 6 wk of age with both vaccines. Serum antibody levels were analyzed before (0) and 1, 2, 3, 4, 5, 12, and 21 wk postvaccination (wpv). The High lines displayed a significantly higher response than Low to both MG and PM. The difference in ymax between High and Low lines was 3.25-fold for PM response and 1.5-fold for MG response. Low lines had a significantly (P < 0.05) later tmax than High lines to MG, but not to PM. There was a significant (P < 0.05) positive correlation between the antibody responses to MG and PM, in High lines for the antibody ratios 0, 3, and 21 wpv and in Low lines for 0, 12, and 21 wpv. The ymax and tmax of antibody responses to the two vaccines were not correlated. The results on the kinetic differences of the antibody responses to MG and PM suggest that the kinetics and persistence of antibody reaction have different genetic regulation in response to each vaccine.

Immune system dysfunction during exposure to poult enteritis and mortality syndrome agents

Poult Enteritis and Mortality Syndrome (PEMS) is a condition of yet undefined etiology. Affected flocks may exhibit 100% morbidity with mortality up to 50% or more between 2 to 4 wk of age. The current study reports the immune status of poults experimentally infected with PEMS agent(s) in various trials. When compared with the unchallenged controls, PEMS-infected poults had significant atrophy of the bursa (up to 2-fold), thymus (up to 11-fold), and spleen (up to 2-fold) (P < or = 0.05). When challenged with SRBC, PEMS-infected poults had 1 to 2 log2 lower anti-SRBC antibody titers than the controls (P < or = 0.05). Responsiveness to a mitogenic lectin, phytohemagglutinin-P, was reduced significantly in PEMS poults (P < or = 0.05). These data show that the immune system of the poults is compromised significantly during PEMS infection in terms of lymphoid organ integrity and humoral and cell-mediated immunity. These findings imply, therefore, that immune dysfunction may contribute to the mortality observed during PEMS outbreaks.