High feather corticosterone indicates better coccidian infection resistance in greenfinches

Differential exposure or sensitivity to stressors can have substantial effects on the variation in immune responsiveness of animals. However, the questions about the causes and consequences of these processes have remained largely unclear, particularly as regards wild animals and their natural pathogens. Here we ask how a potential marker of stress responses, the feather corticosterone (CORT) content, reflects the resistance to an experimental infection with natural coccidian parasites in wild-caught captive greenfinches (Carduelis chloris). CORT content of tail feathers grown in captivity correlated positively with a behavioural measure of captivity-intolerance, i.e., the amount of damage accrued to tail feathers in captivity that results from flapping against cage bars. This finding is consistent with an idea that feather CORT reflects the amount of stress experienced during feather growth. Experimental infection with heterologous coccidian strains increased feather CORT levels. Birds with highest feather CORT levels appeared most resistant to new infection, assessed on the basis of parasite oocyst shedding at the peak phase of infection. Birds with highest feather CORT levels also cleared the infection faster than the birds with lower feather CORT levels. These findings provide the first evidence about positive covariation between feather CORT and resistance to a natural pathogen in a wild bird species. Assuming that feather CORT levels reflect circulating hormone titres, these findings suggest that parasite-mediated selection may contribute to maintenance of phenotypes with high corticosterone responsiveness to stress, despite potential negative behavioural consequences.

A comparison of the antibody responses between specific pathogen-free and commercial layers immunized with an influenza vaccine prepared from inactivated non-pathogenic H5N1 virus by single shot

It is known that antibody responses in chickens against invading organisms or antigens are considerably different among different lines. Thus, an avian influenza vaccine was prepared from inactivated whole particles of the virus of non-pathogenic strain A/duck/Hokkaido/Vac-1/04 (H5N1) using an oil adjuvant containing anhydromannitol-octadecenoate-ether and injected intramuscularly into each ten 10-week-old specific pathogen-free (SPF) white leghorn chickens and commercial layers of Julia and Boris-Brown to obtain comparative data for antibody responses until 6 weeks after vaccination. Despite significant partial differences of antibody titer between the chicken lines, this study clearly showed that the vaccine induced good and sufficient antibody response in both SPF chickens and commercial layers.

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.

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.

Immune competence of chicks from two lines divergently selected for antibody response to sheep red blood cells as affected by supplemental vitamin E

Effects of dietary vitamin E on responses to SRBC antigens and Escherichia coli infection were studied in chicks from White Leghorn lines selected for 24 generations for high (HAS) and low (LAS) antibody responses to SRBC. Chicks were fed corn-soybean diets consisting of either high (300 IU per kg feed) or low (10 IU per kg feed) concentrations of vitamin E from the day of hatch through the end of experiment. The LAS chicks were heavier than the HAS chicks at 14 d of age and thereafter; there was no difference in BW between vitamin E concentrations. At 37 d of age, chicks were inoculated via the brachial vein with 0.1 mL of 0.25% SRBC suspension. Antibody titers at 6 and 10 d after inoculation were higher in HAS than in LAS chicks. At 6 and 10 d after inoculation with SRBC, antibody responses were lower in LAS chicks fed the diet containing the higher vitamin E concentration than in those fed the diet containing the lower concentration of vitamin E. At 64 d of age, chicks were injected in the posterior thoracic air sac with 0.1 mL of 10(-2) or 10(-4) dilution of Escherichia coli and scored for pericardial and air sac lesions. The HAS chicks were more susceptible to E. coli infection than LAS chicks as measured by lesion scores and BW changes. Although dietary vitamin E had no effect on lesion scores in either line, BW loss at 24 h after E. coli inoculation was significantly reduced in HAS chicks fed the higher concentration of vitamin E. The dosage of E. coli had no effect on lesion scores and BW changes. These results suggest that genetic selection might have changed immune competence in relation to responses to dietary vitamin E, and the optimum dietary concentration of vitamin E depends on genotype, among other factors.

Kinetics of antibody responses in hens from chicken lines divergently selected for response to sheep red blood cells

Changes in antibody titers to SRBC were monitored for 180 d after inoculation in hens from two lines divergently selected for 24 generations for high (HAS) or low (LAS) antibody response to SRBC. The HAS hens not only had a higher peak of antibody response (12.9 vs 9.4), but also showed greater persistence in maintaining antibody levels than LAS hens. As a result, HAS hens exhibited higher antibody titers for the 180-d assay period than LAS hens. Antibodies to SRBC were detected in all day-old chicks hatched from HAS eggs collected 10 to 14 d after inoculation as well as 92 to 119 d after inoculation. Only a portion (20 to 75%) of progeny for LAS hens had detectable levels of antibody during the same periods. Among responders, antibody titers were higher for HAS than for LAS progeny. There was a positive correlation among antibody titers taken at different times after the inoculation with SRBC.

Immunoresponsiveness in chickens: association of antibody production and the B system of the major histocompatibility complex

Lines of White Leghorn chickens were selected for high or low antibody response to sheep erythrocytes for five generations. The base population from which the experiment started was composed of individuals all of which were heterozygous at the MHC haplotypes B13 and B21. Body weights, egg production traits, and genotypes at the B system were monitored for all individuals in each generation. By Generations 4 and 5 there was separation of the two replicate lines selected for high titer from the two replicate lines selected for low titer. Over the course of the experiment, higher antibody titers and lower BW were associated with B21 and lower antibody titers and higher BW were associated with B13, although these relationships did not occur in every instance. Conclusions were that the B system was associated with antibody response, but that the chickens did not depend entirely upon that association for protection against foreign proteins. Also, the importance of having replicate lines in a selection experiment was shown.

Antigen-specific T cell proliferation following coccidia infection

Coccidia antigen-specific T lymphocyte proliferation induced by Eimeria acervulina was measured in chickens congenic at the major histocompatibility complex and in two unrelated lines. Sporozoites and merozoites induced high proliferation of lymphocytes following primary infection, with similar changes seen for splenic or peripheral blood lymphocytes. Highest antigen-specific proliferation after both primary and secondary infection was seen in Line 15I5, which contributed the background genome to the congenic lines. In general, merozoites elicited higher proliferation responses than sporozoites. Analyses of differences between uninfected and infected chickens showed that, at some points in the infection cycle, proliferation of lymphocytes was greater and at other times less for infected than uninfected chickens.

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)