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Abstract: Crossbreeding parameters of immune response traits were estimated from a set of well characterized crossbred populations derived from three chicken lines selected over 12 generations for three different general immune response traits and their F1, F2 and backcrosses. The three traits investigated were the selection criteria from each of the lines, i.e. antibody response to the Newcastle disease virus vaccine 3 weeks after vaccination (ND3), cell-mediated immune response (response to phytohemagglutinin, PHA) and phagocytic activity measured as carbon clearance (CC). Crossbreeding parameters included direct and maternal additive line effects, direct and maternal heterosis as well as direct epistatic recombination loss. They were estimated as linear combinations of genetic group effects estimated using animal model methodology. Significant line differences were obtained for ND3 and, to a lesser extent, CC. They were mainly due to direct effects, maternal effects being significant for none of the 3 traits. Significantly negative direct heterosis effects were also observed for ND3 and CC, but not for PHA. Maternal heterosis effects were not estimated for CC. They were non significant for PHA, and negative and significant (−0.78±0.24⁎⁎) for ND3. The significant favourable recombination gain estimated for ND3 (3.21±0.88⁎⁎⁎) indicates that epistatic interactions could be important for this trait. The present work shows that it was worthwhile to complete second generation crosses to be able to assess to what extent immunity gained by selection is maintained in advanced crossbred generations, and to compare the transmission of immune traits implicated in different aspects of immunity. [Copyright &y& Elsevier]

Corticosterone plasma concentration was measured in a random-bred control line and in 3 White Leghorn chicken lines previously selected over 9 generations for 3 different in vivo immune responses: high antibody response to Newcastle disease virus vaccine 3 wk after vaccination (ND3), high cell-mediated immune response (response to phytohemagglutinin, PHA), and high phagocytic activity measured as carbon clearance (CC). The objective of the study was to estimate if selection on immune response had an effect on the response to stress assessed by measures of corticosterone concentration before and after physical stress or adrenocorticotropin hormone injection and if the effect was dependent on the immune response trait that had been selected for, by joint analyses of immune responses and concentrations. The mean values of plasma corticosterone measures did not differ between lines, indicating that selection for different high immune responses had little effect on response to stress. Within line, however, significant negative correlations (-0.46 ⩽ r ⩽ -0.39) were found between cell-mediated immunity and corticosterone plasma concentrations in 3 of the 4 lines. Moreover, in the line selected for high antibody titers (ND3-L), corticosterone levels were positively correlated to ND3 (r = 0.41 and 0.47) and negatively correlated to CC (r = -0.48). [ABSTRACT FROM AUTHOR]

Planned crosses were designed to produce an F2 and 2 backcross populations from 2 lines of White Leghorn chickens previously selected over 10 generations for 2 different in vivo immune responses. The selection criteria applied on the 2 grandparental lines were as follows: high antibody response to Newcastle disease virus vaccine 3 wk after vaccination (ND3) and high cell-mediated immune response [response to phytohemagglutinin]. Furthermore a control line was kept by random breeding. The objective of the study was to estimate if the 2 selection criteria applied on the pure lines had changed the level of and type of immune (humoral) response to a new antigen, keyhole limpet hemocyanin (KLH), in the various second-generation progeny groups. In addition, correlations between parameters of acquired and innate immunity were tested. Primary total (IgT) and isotype-specific (IgG and IgM) antibody response to KLH 1 wk after immunization and levels of natural antibodies (NAB) binding to Salmonella enteriditis-derived lipopolysaccharide (LPS) were measured. Although no differences were present between IgM and IgG antibodies to KLH and the phytohemagglutinin skin-swelling response, significant differences were present between all the progeny groups for IgT to KLH and ND3 and NAB binding to LPS. The mean values for lgT to ND3 and KLH were significantly different between the crosses using the selected lines compared with the control line, indicating a contribution of the previous selection. In addition, a sex effect was found for IgM to KLH and NAB to LPS, for which females had a higher response than males in both cases. No interaction between progeny type and sex was found. Furthermore, significant positive correlations were found between NAB to LPS and specific antibody titers to KLH. Finally, the results of the present study demonstrated an interaction between innate and acquired irnmunity under this strategy of selection and crossbreeding and confirmed the effect of selection on general immune response to a new antigen in second-generation crosses. [ABSTRACT FROM AUTHOR]

Natural antibodies (NA) create a crucial barrier at the initial steps of the innate humoral immune response. The main role of NA in the defense system is to bind the pathogens at early stages of infection. Different pathogens are recognized by the presence of highly conserved antigen determinant [e.g., lipopolysaccharide (LPS) in gram-negative bacteria or lipoteichoic acid (LTA) in gram-positive bacteria]. In chickens, a different genetic background of NA binds LPS and LTA antigens, encoded by different QTL. The main objective of this work was to confirm known QTL associated with LPS and LTA NA. For this purpose a chicken reference population was created by crossing 2 breeds: a commercial layer, White Leghorn, and a Polish indigenous chicken, Green-Legged Partridgelike. The chromosomal regions analyzed harbored to GGA3, GGA5, GGA6, GGA8, GGA9, GGA10, GGA14, GGA15, GGA18, and GGAZ. The data collected consisted of the NA titers binding LPS and LTA (determined by ELISA at 12 wk of age) as well as the genotypes (30 short tandem repeat markers; average of 3 markers/chromosome, collected for generations F0, F1, and F2). The analyses were performed with 3 statistical models (paternal and maternal half-sib, line cross, and linkage analysis and linkage disequilibrium) implemented in GridQTL software (http://www.gridqtl.org.uk/). The QTL study of humoral innate immune response traits resulted in the confirmation of 3 QTL associated with NA titers binding LPS (located on GGA9, GGA18, and GGAZ) and 2 QTL associated with NA titers binding LTA (located on GGA5 and GGA14). A set of candidate genes within the regions of the validated QTL has been proposed. [ABSTRACT FROM AUTHOR]

A QTL involved in the primary antibody response toward keyhole limpet hemocyanin (KLH) was detected on chicken chromosome 14 in the experimental population, which was created by crossing commercial White Leghorn and a Polish native chicken breed (green-legged partridgelike). The current QTL location is a validation of previous experiments pointing to the same genomic location for the QTL linked to a primary antibody response to KLH. An experimental population was typed with microsatellite markers distributed over the chicken chromosome 14. Titers of antibodies binding KLH were measured for all individuals by ELI- SA. Statistical models applied in the Grid QTL Web-based software were used to analyze the data: a half-sib model, a line-cross model, and combined analysis in a linkage disequilibrium and linkage analysis model. Candidate genes that have been proposed were genotyped with SNP located in genes exons. Statistical analyses of single SNP associations were performed pointing out 2 SNP of an axis inhibitor protein (AXIN1) gene as significantly associated with the trait of an interest. [ABSTRACT FROM AUTHOR]