Divergent selection of chickens for antibody production to sheep erythrocytes: age effect in parental lines and their crosses

Age dependency of antibody response to sheep red blood cell (SRBC) antigen was measured in lines of chickens divergently selected for this trait and in reciprocal crosses between them. At 7 days of age, there were differences among populations for frequency of responders to SRBC antigen. This qualitative pattern persisted in the quantitative context of the antibody titers of those who responded, demonstrating genetic differences in both the event and subsequent levels of antibody. Although chickens from the high line had significantly higher titers than those from the low line and cross populations, all reached serological maturity by 14 days of age. From this age, high-line chickens had higher bursa and spleen weights and lower thymus weights relative to body weight than those from the low line: relative to body weight, spleen and bursa weights increased at a faster rate through 19 and 25 days of age, respectively, and then plateaued. In contrast, there was a progressive increase in thymus weight relative to body weight through 40 days of age.     

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 × 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.     

Effect of short-term exposure of chickens to corticosterone on resistance to challenge exposure with Escherichia coli and antibody response to sheep erythrocytes.

Chickens in a low-stress environment (heterophil/lymphocyte ratio 0.31) were given feed containing 30, 40, or 60 mg of corticosterone/kg of feed for 0.5 hour. Between 0.5 to 12 hours later, chickens were exposed to Escherichia coli via the air sac route. For each dose of corticosterone, there was an untreated control group that was exposed to E coli via the air sac route. The prevalence of pericarditis was reduced from 78 to 7% between 2 and 4 hours after exposure. Resistance was associated with heterophil/lymphocyte (H/L) ratios greater than 1.04. Peak H/L ratios correlated positively with amount of corticosterone in the feed. In one experiment, chickens were inoculated IV with sheep erythrocytes at various times after consumption of feed containing corticosterone. Suppression of antibody responsiveness was most pronounced 4 hours later. Antibody responsiveness correlated positively with lymphocyte numbers. Histologic examination of air sacs was made following euthanasia at various times after E coli exposure. Lesions observed in control chickens included: edema at 0.5 hour, beginning of heterophil infiltration at 1 hour, increased edema and heterophil infiltration at 2 hours, and severe edema and heterophil infiltration at 4 hours. Lesions were not observed in chickens that had been given feed containing 40 mg of corticosterone/kg of feed.     

Associations of interferon-gamma genotype and protein level with antibody response kinetics in chickens

Although previous studies have demonstrated an association between interferon-gamma (IFN-gamma) promoter genotype and antibody response kinetics in chickens, the protein levels that may mediate such a gene-trait association have not been determined. The objective of this study, therefore, was to determine the correlation of circulating IFN-gamma levels with both the IFN-gammaIFN-gamma promoter polymorphisms and antibody response in order to evaluate the potential role of IFN-gamma protein in mediating genetic control of antibody response in chickens. Antibody response after Salmonella enteritidis (SE) vaccination at day 10, antibody response to sheep red blood cells (SRBCs) and killed Brucella abortus after immunizations at 19 wk and 22 wk, and serum IFN-gamma protein level were measured in an F2 population derived from inbred lines. A single nucleotide polymorphism in the IFN-gamma promoter region was associated with IFN-gamma protein expression as measured by an enzyme-linked immunosorbent assay after both primary and secondary immunizations. Higher IFN-gamma protein level was correlated with higher antibody level to SE and with increased maximum level and decreased time to reach the maximum secondary antibody response to SRBCs. These results suggest that one of the mechanisms by which promoter polymorphism of IFN-gamma affects antibody production in chickens may involve the circulating level of IFN-gamma protein.     

Divergent selection for uterine capacity in rabbits. I. Genetic parameters and response to selection

A 10-generation divergent selection experiment for uterine capacity (UC) measured as litter size in unilaterally ovariectomized females was carried out in rabbits. A total of 2,996 observations on uterine capacity of does (up to four parities) was recorded. Laparoscopy was performed at d 12 of their second gestation, and ovulation rate (OR) and number of implanted embryos (IE) were recorded in 735 does. Prenatal survival (PS) was assessed as UC/OR, embryo survival (ES) as IE/OR, and fetal survival (FS) as UC/IE. Genetic parameters and genetic trends were inferred using Bayesian methods. Marginal posterior distributions of all unknowns were estimated by Gibbs sampling. Heritabilities of UC, OR, IE, ES, FS, and PS were 0.11, 0.32, 0.22, 0.04, 0.14, and 0.09, respectively. Genetic and phenotypic correlations between FS and ES were low, suggesting different biological mechanisms for the two periods of survival. After 10 generations of selection, the divergence was approximately 1.5 rabbits, or approximately 1% per generation. Approximately one-half of this response was obtained in the first two generations of selection, which may suggest the presence of a major gene segregating in the base population.     

Divergent selection for fleece weight in French Angora rabbits: Non-genetic effects, genetic parameters and response to selection

In order to explore genetic variability of wool production and other quantitative traits, an 8-cohort divergent selection experiment for total fleece weight (TFW) was carried out in French Angora rabbits. Studies were made on the wool production of 669 female rabbits born between 1994 and 2001 and having produced wool from the third to 12th harvests. The aim of the selection experiment was to obtain two divergent lines (low and high) on total fleece weight. The studied traits included total fleece weight, weight of the two qualities of wool (WAJ1 and WAW1), homogeneity (HOM), live body weight at ages of 4 (LW4), 8 (LW8), 12 (LW12), 16 (LW16), and 20 (LW20) weeks and then 9 weeks before each harvest (9LW). A preliminary analysis of non-genetic factors was done with the GLM procedure. The genetic parameters and genetic trends were analysed using a BLUP animal model. Heritability estimates for TFW, WAJ1, WAW1, HOM, LW4, LW8, LW12, LW16, LW20 and 9LW were 0.38, 0.30, 0.10, 0.06, 0.30, 0.09, 0.14, 0.32, 0.39 and 0.45, respectively. Genetic and phenotypic correlations between TFW and WAJ1 were high (0.98 ± 0.01 and 0.89 ± 0.01, respectively). There was a low genetic correlation between TFW and 9LW (0.26 ± 0.12). After eight cohorts of selection, the divergence between the lines was approximately three genetic standard deviations. Selection for total fleece weight had a generally beneficial effect on fleece quality.     

Variations in sheep serum conglutinating and haemolytic activity for sheep erythrocytes sensitized by rabbit antibody

Based on conglutinating and haemolytic reactions with sheep erythrocytes (E) sensitized by rabbit antibody (A), three types of sheep sera were encountered. Type 1 sera do not conglutinate or haemolyse sheep E-rabbit A. Type 2 sera failed to conglutinate, but are haemolytically active. Type 3 sera have both activities. Serum from one type 1 sheep still failed to conglutinate 5 days after venepuncture but was now haemolytically active (i.e., type 2). Some sheep that initially had type 2 sera had, five days after an intraperitoneal injection of yeast cells, sera with conglutinating activity (type 3 sera). Type 1, 2 and 3 sera all had haemolytic activity with human E-sheep A indicator cells.Pooled type 3 sera have the highest conglutinating titres with sheep E-rabbit A after 10 min incubation at 39 °C. At this stage, the haemolytic titres were very low. From 10 min, the conglutinating titres decreased whereas the haemolytic titres gradually increased until 80 min. Optimal conglutinating activity required less rabbit A to sensitize sheep E than did haemolytic activity.     

Genetic architecture of antibody responses of chickens to sheep red blood cells

SUMMARY: Two lines of White Leghorn chickens selected divergently for high (HH) or low (LL) antibody response 5 days after an injection with 0.1 ml of 0.25% suspension of sheep red blood cell (SRBC) antigen were used to produce parental, reciprocal F(1) , F(2) and backcross progeny. At 36 days of age males and females of the various progeny types were injected with SRBC suspension and antibody titres measured at 5 and 12 days later. Progeny of the high antibody line had higher titres at both 5 and 12 days after inoculation with SRBC than those of the low line. Reciprocal effects for SRBC titres were important only for female progeny suggesting sex-linked effects of the Z chromosome. Titres for F(1) progeny were intermediate and different from the parental lines at both 5 and 12 days after inoculation. Antibody titres 5 days after inoculation exhibited heterosis which emanated from the homogametic sex. Although maternal effects generally had no influence on antibody titres, maternal heterosis in the selected trait was due to sex-linkage. Recombination effects were negligible for both traits. ZUSAMMENFASSUNG: Genetische Architekture der Antik?rperreaktion von Hühnern auf Schaferythrozyten Zwei Wei?e Leghorn-Linien, gegens?tzlich selektiert auf starke (HH) oder niedrige (LL) Antik?rperreaktion 5 Tage nach Injektion von 0,1 ml einer 0,25% Schaferythrozytensuspension (SRBC), wurden zur Erzeugung von parentalen, reziproken F(1) , F(2) und Rückkreuzungsnachkommen herangezogen. In Alter von 36 Tagen wurde den Tieren eine SRBC Suspension injiziert und Antik?rpertiter 5 und 12 Tage sp?ter bestimmt. Nachkommen der HH Linie hatten an beiden Tagen h?here Titer als LL Nachkommen. Reziproke Effekte für SRBC Titer waren nur bei weiblichen Nachkommen wichtig, bedingt wohl durch geschlechtsgekoppelte Z-Chromosom Einflüsse. Die Titer der F(1) Nachkommen waren zwischen denen der Elternlinien. Antik?rpertiter 5 Tage nach Injektion zeigten Heterosis, die im homogametischen Geschlecht auftrat. Obwohl im allgemeinen maternale Wirkungen keinen Einflu? zeigten, war maternale Heterosis beim selektierten Merkmal auf Geschlechtskopplung zurückzuführen. Rekombinations-wirkungen waren vernachl?ssigbar.     

Genetic-environmental interactions and antibody response in chickens to two antigens

Chickens from lines selected for either a high (HA) or low (LA) antibody response to sheep erythrocytes were either socialized, ignored, or stressed before being injected with two different erythrocyte antigens. Correlation between the antibody responses to the two antigens and the difference between the titers of the HA and LA lines was greatest when the chickens were socialized in an optimum-stress environment. The antibody responses of individual chickens to the two antigens was influenced by their heterophil/lymphocyte ratios.     

Divergent selection for immune responsiveness in chickens: estimation of realized heritability with an animal model.

With the aim of improving general disease resistance, chickens were divergently selected for their antibody titers 5 d after immunization with sheep red blood cells for nine generations. Selected and control lines differed significantly for primary and secondary responses after three generations. Heritability of the antibody titer was estimated by REML fitting an animal model using a derivative-free algorithm. The heritability estimate using data on all lines simultaneously was .31. Realized heritability of the antibody titer in the selected lines was estimated by using either the phenotypic cumulative response as the deviation from the control line or the mean breeding values obtained with an animal model. Values from the two methods were consistent, giving a realized heritability of .21 and .25 in the high and low lines, respectively. The genetic trend was not linear and the response to selection tended to accelerate over generations.     

The effect of Bacillus natto in feed on the sheep red blood cell antibody response in chickens

Chickens fed 10(6) or 10(7) of Bacillus natto strain BN/g of diet from hatching through 15 or 30 days of age showed an increase in ability to produce hemagglutinating antibody titer as determined by intravenous injection of sheep red blood cells, whereas no increase in antibody production ability was observed in the chickens fed 10(7) of BN/g of diet from hatching through 10 days of age.     

The antibody response of sheep to vaccination against Johne's disease

Extract

Vaccination has been promoted for the control of Johne's disease in sheep. At present vaccination is used especially in merino flocks.     

Serum and abomasal antibody response of sheep to infections with Haemonchus contortus

Serum and abomasal IgA, IgG and IgM antibody response against adult worm, L3 and egg antigens of Haemonchus contortus was monitored by the ELISA technique after one or two infections with this nematode. Following the first infection, antibody levels in serum did not change materially. After administration of a challenge dose of infective larvae, antibodies of the three immunoglobulin classes in infected animals rose slightly, but this rise appeared later than the fall in the faecal egg counts. In contrast, in abomasal mucosa, IgA anti-larval antibody levels, which did not increase materially after the primary infection, rose rapidly after a transient inhibition when sheep were challenged. A close temporal relationship was observed between the rise in local anti-worm IgA antibodies and the self-cure reaction, but antibody levels fell rapidly after worm diminution. The local antibody response was thus considered to be related to immunity of sheep to H. contortus.