Lines Of White Leghorn Chickens Research Articles

Growth of White Leghorn Chicken Immune Organs after Long-Term Divergent Selection for High or Low Antibody Response to Sheep Red Blood Cells.

Long-term divergent selection from a common founder population for a single trait-antibody response to sheep erythrocytes 5 days post-injection-has resulted in two distinct lines of White Leghorn chickens with a well-documented difference in antibody titers: high (HAS)- and low (LAS)-antibody selected lines. Subpopulations-high (HAR)- and low (LAR)-antibody relaxed-were developed from generation 24 of the selected lines to relax selection. The objective of the current experiment was to determine if this long-term selection and relaxation of selection impacted the growth of two organs important to chicken immunity: the spleen and the bursa of Fabricius. Spleens and bursae were obtained from ten chickens per line at nine timepoints (E18, D0, D6, D13, D20, D35, D49, D63, and D91) throughout their rapid growth phase and presented as a percent of body weight. Significance was set at p ≤ 0.05. For the spleen, all lines consistently increased in size relative to body weight to D49, followed by a consistent decline. All lines had a similar growth pattern, but HAS spleens grew faster than LAS spleens. For the bursa, LAS was smaller than the other three lines as an embryo and also smaller than HAS through D63. In the selected lines, bursa weight peaked at D35, whereas the relaxed lines peaked at D49. By D91, there was no difference between lines. Artificial and natural selection, represented by the long-term selected and relaxed antibody lines, resulted in differences in the growth patterns and relative weights of the spleen and bursa of Fabricius.

Differences in the microbiome of the small intestine of Leghorn lines divergently selected for antibody titer to sheep erythrocytes suggest roles for commensals in host humoral response.

For forty generations, two lines of White Leghorn chickens have been selected for high (HAS) or low (LAS) antibody response to a low dose injection of sheep red blood cells (SRBCs). Their gut is home to billons of microorganisms and the largest number of immune cells in the body; therefore, the objective of this experiment was to gain understanding of the ways the microbiome may influence the differential antibody response observed in these lines. We achieved this by characterizing the small intestinal microbiome of HAS and LAS chickens, determining their functional microbiome profiles, and by using machine learning to identify microbes which best differentiate HAS from LAS and associating the abundance of those microbes with host gene expression. Microbiome sequencing revealed greater diversity in LAS but statistically higher abundance of several strains, particularly those of Lactobacillus, in HAS. Enrichment of microbial metabolites implicated in immune response such as lactic acid, short chain fatty acids, amino acids, and vitamins were different between HAS and LAS. The abundance of several microbial strains corresponds to enriched host gene expression pathways related to immune response. These data provide a compelling argument that the microbiome is both likely affected by host divergent genetic selection and that it exerts influence on host antibody response by various mechanisms.

Combining supervised machine learning with statistics reveals differential gene expression patterns related to energy metabolism in the jejuna of chickens divergently selected for antibody response to sheep red blood cells

Since the 1970s, 2 lines of White Leghorn chickens, HAS and LAS, have been continuously divergently selected for 5-day postinjection antibody titer to injection with sheep red blood cells (SRBC). Antibody response is a complex genetic trait and characterizing differences in gene expression could facilitate better understanding of physiological changes due to selection and antigen exposure. At 41 d of age, randomly selected HAS and LAS chickens, which had been coraised from hatch, were either injected with SRBC (HASI and LASI) or kept as the noninjected cohort (HASN and LASN). Five days later, all were euthanized, and samples collected from the jejunum for RNA isolation and sequencing. Resulting gene expression data were analyzed combining traditional statistics with machine learning to obtain signature gene lists for functional analysis. Differences in ATP production and cellular processes were observed in the jejunum between lines and following SRBC injection. HASN vs. LASN exhibited upregulation of ATP production, immune cell motility, and inflammation. LASI exhibits upregulation of ATP production and protein synthesis vs. LASN, reflective of what was observed in HASN vs. LASN. In contrast, no corresponding upregulation of ATP production was observed in HASI vs. HASN, and most other cellular processes appear inhibited. Without exposure to SRBC, gene expression in the jejunum indicates HAS generates more ATP than LAS, suggesting HAS maintains a "primed" system; and gene expression of HASI vs. HASN further suggests this basal ATP production is sufficient for robust antibody responses. Conversely, LASI vs. LASN jejunal gene expression implies a physiological need for increased ATP production with only minimal correlating antibody production. The results of this experiment provide insight into energetic resource needs and allocations in the jejunum in response to genetic selection and antigen exposure in HAS and LAS which may help explain phenotypic differences observed in antibody response.

MicroRNAs with non-additive expression in the ovary of hybrid hens target genes enriched in key reproductive pathways that may influence heterosis for egg laying traits.

Heterosis has been extensively exploited in chicken breeding to improve laying traits in commercial hybrid stock. However, the molecular mechanisms underlying it remains elusive. This study characterizes the miRNAome in the pre-hierarchical follicles of purebred and hybrid laying hens, and investigate the functions of miRNAs with non-additive expression in the pre-hierarchical follicles as they modulate heterosis for egg number and clutch size. To achieve that aim, White Leghorn and Rhode Island Red chicken lines were reciprocally crossed to generate hybrids. The crossbreds demonstrated heterosis for egg number and clutch size, and pre-hierarchical follicles from 4 birds of each genotype were collected at 53 weeks of age. Mode of miRNA expression was characterized after miRNA sequencing. A total of 50 miRNAs including 30 novel ones, were found to exhibit non-additive expression. Dominance was the predominant mode of expression exhibited by majority of the miRNAs. Functional analysis of target genes of the known miRNAs with non-additive expression revealed Gene Ontology terms related to regulation of transcription, metabolic processes and gene expression. KEGG and REACTOME pathways including hedgehog, cellular senescence, wnt, TGF-β, progesterone-mediated oocyte maturation, oocyte meiosis, GnRH signaling, signal transduction and generic transcription, which can be linked to primordial follicle activation, growth and ovulation, were significantly enriched by target genes of miRNAs with non-additive expression. Majority of the genes enriched in these biological pathways were targeted by gga-miR-19a, gga-miR-19b, gga-miR-375, gga-miR-135a, and gga-miR-7 and 7b, thus, revealing their synergistic roles in enhancing processes that could influence heterosis for egg number and clutch size in hybrid hens.

Interaction of Salmonella Gallinarum and Salmonella Enteritidis with peripheral leucocytes of hens with different laying performance

Salmonella enterica ssp. enterica serovars Enteritidis (SE) and Gallinarum (SG) cause different diseases in chickens. However, both are able to reach the blood stream where heterophils and monocytes are potentially able to phagocytose and kill the pathogens. Using an ex vivo chicken whole blood infection model, we compared the complex interactions of the differentially host-adapted SE and SG with immune cells in blood samples of two White Leghorn chicken lines showing different laying performance (WLA: high producer; R11: low producer). In order to examine the dynamic interaction between peripheral blood leucocytes and the Salmonella serovars, we performed flow cytometric analyses and survival assays measuring (i) leucocyte numbers, (ii) pathogen association with immune cells, (iii) Salmonella viability and (iv) immune gene transcription in infected whole blood over a four-hour co-culture period. Inoculation of blood from the two chicken lines with Salmonella led primarily to an interaction of the bacteria with monocytes, followed by heterophils and thrombocytes. We found higher proportions of monocytes associated with SE than with SG. In blood samples of high producing chickens, a decrease in the numbers of both heterophils and Salmonella was observed. The Salmonella challenge induced transcription of interleukin-8 (IL-8) which was more pronounced in SG- than SE-inoculated blood of R11. In conclusion, the stronger interaction of monocytes with SE than SG and the better survivability of Salmonella in blood of low-producer chickens shows that the host–pathogen interaction and the strength of the immune defence depend on both the Salmonella serovar and the chicken line.

Cloning, characterisation and expression of the SERPINB14 gene, and association of promoter polymorphisms with egg quality traits in layer chicken

ABSTRACT 1. Ovalbumin (SERPINB14) is the most abundant protein present in egg white contributing about 54% of the total egg protein. In this study, the objectives were to clone and characterise the coding sequence of the SERPINB14 gene, to explore its expression profile, identify polymorphisms in the promoter of the gene and explore any association with egg quality traits in White Leghorn chickens. 2. SNPs and mRNA expression of SERPINB14 in White Leghorn chicken lines were detected by PCR-single strand conformation polymorphism (SSCP) along with sequencing and qPCR. The open reading frame (ORF) was cloned in an expression plasmid vector and sequenced. 3. The ORF of this gene was 1161 bp encoding a peptide of 386 amino acids. There were three SNPs observed in the coding region of the gene, one of which was of the mis-sense type, having c562G>A transition which resulted in substitution of alanine to threonine at position 188 in the protein sequence. In both the lines, an increase in expression of the gene was observed after onset of egg production with peak expression at the 40th week of age compared to before onset of lay. The SERPINB14 gene was expressed in the magnum, but not in ovary and infundibulum, tissues of each White Leghorn line. The promoter region of the gene showed SNPs with three haplotypes; H1, H2, and H3. The haplo groups were associated with the egg weight and age at sexual maturity in the IWI line and Haugh unit and albumin index in the IWK line. 4. It was concluded that the ORF of SERPINB14 gene in White Leghorn chicken lines is polymorphic. The promoter region of the gene is also polymorphic and has significant (P < 0.05) association with Haugh unit and egg weight in IWK and IWI chicken lines, respectively.

Kinetics of the Cellular and Transcriptomic Response to Eimeria maxima in Relatively Resistant and Susceptible Chicken Lines.

Eimeria maxima is a common cause of coccidiosis in chickens, a disease that has a huge economic impact on poultry production. Knowledge of immunity to E. maxima and the specific mechanisms that contribute to differing levels of resistance observed between chicken breeds and between congenic lines derived from a single breed of chickens is required. This study aimed to define differences in the kinetics of the immune response of two inbred lines of White Leghorn chickens that exhibit differential resistance (line C.B12) or susceptibility (line 15I) to infection by E. maxima. Line C.B12 and 15I chickens were infected with E. maxima and transcriptome analysis of jejunal tissue was performed at 2, 4, 6 and 8 days post-infection (dpi). RNA-Seq analysis revealed differences in the rapidity and magnitude of cytokine transcription responses post-infection between the two lines. In particular, IFN-γ and IL-10 transcript expression increased in the jejunum earlier in line C.B12 (at 4 dpi) compared to line 15I (at 6 dpi). Line C.B12 chickens exhibited increases of IFNG and IL10 mRNA in the jejunum at 4 dpi, whereas in line 15I transcription was delayed but increased to a greater extent. RT-qPCR and ELISAs confirmed the results of the transcriptomic study. Higher serum IL-10 correlated strongly with higher E. maxima replication in line 15I compared to line C.B12 chickens. Overall, the findings suggest early induction of the IFN-γ and IL-10 responses, as well as immune-related genes including IL21 at 4 dpi identified by RNA-Seq, may be key to resistance to E. maxima.

High-throughput sequencing reveals differing immune responses in the intestinal mucosa of two inbred lines afflicted with necrotic enteritis

We investigated the necrotic enteritis (NE)-induced transcripts of immune-related genes in the intestinal mucosa of two highly inbred White Leghorn chicken lines, line 6.3 and line 7.2, which share the same MHC haplotype and show different levels of NE susceptibility using high-throughput RNA sequencing (RNA-Seq) technology. NE was induced by the previously described co-infection model using Eimeria maxima and Clostridium perfringens. The RNA-Seq generated over 38 million sequence reads for Marek's disease (MD)-resistant line 6.3 and over 40 million reads for the MD-susceptible line 7.2. Alignment of these sequences with the Gallus gallus genome database revealed the expression of over 29,900 gene transcripts induced by NE in these two lines, among which 7,841 genes were significantly upregulated and 2,919 genes were downregulated in line 6.3 chickens and 6,043 genes were significantly upregulated and 2,764 genes were downregulated in NE-induced line 7.2 compared with their uninfected controls. Analysis of 560 differentially expressed genes (DEGs) using the gene ontology database revealed annotations for 246 biological processes, 215 molecular functions, and 81 cellular components. Among the 53 cytokines and 96 cytokine receptors, 15 cytokines and 29 cytokine receptors were highly expressed in line 6.3, whereas the expression of 15 cytokines and 15 cytokine receptors was higher in line 7.2 than in line 6.3 (fold change≥2, p<0.01). In a hierarchical cluster analysis of novel mRNAs, the novel mRNA transcriptome showed higher expression in line 6.3 than in line 7.2, which is consistent with the expression profile of immune-related target genes.In qRT-PCR and RNA-Seq analysis, all the genes examined showed similar responses to NE (correlation coefficient R=0.85–0.89, p<0.01) in both lines 6.3 and 7.2. This study is the first report describing NE-induced DEGs and novel transcriptomes using RNA-seq data from two inbred chicken lines showing different levels of NE susceptibility. These findings provide important insights into our current knowledge of host-pathogen interaction and the nature of host genes that can serve as NE resistance markers for molecular breeding.

Quantitative trait loci segregating in crosses between New Hampshire and White Leghorn chicken lines: IV. Growth performance.

Reciprocal crosses between the inbred lines New Hampshire (NHI) and White Leghorn (WL77) comprising 579 F2 individuals were used to map QTL for body weight and composition. Here, we examine the growth performance until 20 weeks of age. Linkage analysis provided evidence for highly significant QTL on GGA1, 2, 4, 10 and 27 which had specific effects on early or late growth. The highest QTL effects, accounting for 4.6-25.6% of the phenotypic F2 variance, were found on the distal region of GGA4 between 142 and 170 cM (F ≥ 13.68). The NHI QTL allele increased body mass by 141.86 g at 20 weeks. Using body weight as a covariate in the analysis of body composition traits provided evidence for genes in the GGA4 QTL region affecting fat mass independently of body mass. The QTL effect size differed between sexes and depended on the direction of cross. TBC1D1, CCKAR and PPARGC1A are functional candidate genes in the QTL peak region. Our study confirmed the importance of the distal GGA4 region for chicken growth performance. The strong effect of the GGA4 QTL makes fine mapping and gene discovery feasible.

Genomic Regions associated with Necrotic Enteritis Resistance in Fayoumi and White Leghorn Chickens

In this study, we used two breeds of chicken to identify genomic regions corresponding to necrotic enteritis (NE) resistance. We scanned the genomes of a resistant and susceptible line of Fayoumi and White Leghorn chickens (20 birds/line) using a chicken 60 K Illumina SNP panel. A total of 235 loci with divergently fixed alleles were identified across the genome in both breeds; particularly, several clusters of multiple loci with fixed alleles were found in five narrow regions. Moreover, consensus 15-SNP haplotypes that were shared by the resistant lines of both breeds were identified on chromosomes 3, 7 and 9. Genes responsible for NE resistance were identified in chicken lines selected for resistance and susceptibility. Annotation of the regions spanning clustered divergently fixed regions revealed a set of interesting candidate genes such as phosphoinositide-3-kinase, regulatory subunit 5, p101 (PIK3R5) and inositol 1,4,5-trisphosphate receptor 1 (ITPR1), which participate in immune response. Consensus haplotypes were found in regions containing possibly relevant genes, such as myostatin and myosin, which play important roles in muscle development. Thus, genome scans of divergent selection in multiple chicken lines and breeds can be used to identify genomic regions associated with NE resistance.

Modulation of microRNAs in two genetically disparate chicken lines showing different necrotic enteritis disease susceptibility

MicroRNAs (miRNA) play a critical role in post-transcriptional regulation by influencing the 3′-UTR of target genes. Using two inbred White Leghorn chicken lines, line 6.3 and line 7.2 showing Marek's disease-resistant and -susceptible phenotypes, respectively, we used small RNA high-throughput sequencing (HTS) to investigate whether miRNAs are differently expressed in these two chicken lines after inducing necrotic enteritis (NE). The 12 miRNAs, selected from the most down-regulated or up-regulated miRNAs following NE induction, were confirmed by their expressions in real-time PCR. Among these miRNAs, miR-215, miR-217, miR-194, miR-200a, miR-200b, miR-216a, miR-216b, and miR-429 were highly expressed in intestine derived from line 7.2, whereas, miR-1782 and miR-499 were down-regulated. In spleen, miR-34b and miR-1684 were the most up-regulated miRNAs in line 6.3. Notably, five out of six target genes, CXCR5, BCL2, GJA1, TCF12, and TAB3 were differentially expressed between line 6.3 and line 7.2, and showed suppression in the MD-susceptible chicken line. Their expression levels were conversely correlated with those of miRNA obtained from both HTS and quantitative real-time PCR.These results suggest that some miRNAs are differentially altered in response to NE and they modulate the expression of their target genes in the two inbred lines. Collectively, HTS analysis of intestinal miRNAs from NE-afflicted inbred chickens showing different disease phenotypes led to the identification of host immunity genes regulated by miRNA. Future studies of the function of these miRNAs and their target genes in the host will lead to enhanced understanding of molecular mechanisms controlling host-pathogen interaction in NE.

Quantitative trait loci segregating in crosses between New Hampshire and White Leghorn chicken lines: III. Fat deposition and intramuscular fat content

In this study, a genome scan was performed to detect genomic loci that affect fat deposition in white adipose tissues and muscles in 278 F (2) males of reciprocal crosses between the genetically and phenotypically extreme inbred chicken lines New Hampshire (NHI) and White Leghorn (WL77). Genome-wide highly significant quantitative trait loci (QTL) influencing fat deposition in white adipose tissues were found on GGA2 and 4. The peak QTL positions for different visceral and subcutaneous white adipose tissues were located between 41.4 and 112.4 Mb on GGA2 and between 76.2 and 78.7 Mb on GGA4, which explained 4.2-10.4% and 4.3-11.6% respectively of the phenotypic F (2) variances. Contrary to our expectations, the QTL allele descending from the lean line WL77 on GGA4 led to increased fat deposition. We suggest a transgressive action of the obesity allele only if it is not in the genetic background of the line WL77. Additional highly significant loci for subcutaneous adipose tissue mass were identified on GGA12 and 15. For intramuscular fat content, a suggestive QTL was located on GGA14. The analysed crosses provide a valuable resource for further fine mapping of fatness genes and subsequent gene discovery.

Polymorphism at exon 1 of pit-1 gene and its association with immunocompetence traits in layer chicken

A study was designed to explore genetic variability of partial promoter and exon 1 of pit-1 gene and its effect on immune competence traits in White Leghorn chicken. Single stranded conformation polymorphism technique followed by sequencing was employed to detect polymorphism of the gene. Three genotypes (AA, AB and BB) were observed in White Leghorn chicken where two alleles (A and B) were found. AB genotype and A allele were predominant in the population. Different demographic parameters estimated in the White Leghorn chicken lines indicated the presence of genetic divergence among the lines. The pit-1 mRNA expression varied among the genotypes where genotype BB expressed higher than genotype AA and AB. The genotypes as well as alleles showed significant effect (P < 0.05) on sheep RBC titre in White Leghorn chicken.

Quantitative trait loci segregating in crosses between New Hampshire and White Leghorn chicken lines: I. egg production traits

A genome scan was performed to detect chromosomal regions that affect egg production traits in reciprocal crosses between two genetically and phenotypically extreme chicken lines: the partially inbred line New Hampshire (NHI) and the inbred line White Leghorn (WL77). The NHI line had been selected for high growth and WL77 for low egg weight before inbreeding. The result showed a highly significant region on chromosome 4 with multiple QTL for egg production traits between 19.2 and 82.1 Mb. This QTL region explained 4.3 and 16.1% of the phenotypic variance for number of eggs and egg weight in the F(2) population, respectively. The egg weight QTL effects are dependent on the direction of the cross. In addition, genome-wide suggestive QTL for egg weight were found on chromosomes 1, 5, and 9, and for number of eggs on chromosomes 5 and 7. A genome-wide significant QTL affecting age at first egg was mapped on chromosome 1. The difference between the parental lines and the highly significant QTL effects on chromosome 4 will further support fine mapping and candidate gene identification for egg production traits in chicken.

Association Between Candidate Genes of Innate Immunity, Gallinacin Genes and Resistance to Marek’s Disease in Chicken

Gallinacins are antimicrobial peptides that play a significant role in innate immunity in chicken. The aim of this study was to determine the relationship between gallinacin genes and resistance to Marek's disease and to predict whether the amino acids substitutions lead to produce new phenotypes. We used in current study two inbred White Leghorn Lines 6 and 7. We examined gallinacins genes (3-5 and 10) by sequenced a 2.29 kb in two directions from two inbred lines (6 and 7). A total of 10 SNPs were identified within the sequenced regions. This equates to an SNP rate of 4.36 SNPs/kb, nearly to the previously reported 5 SNPs/kb across the entire chicken genome. The current study showed that the gallinacin genes are polymorphic because there are many (SNPs) in both inbred lines of White Leghorn chickens and some of these SNPs are nonsynonymous and others are synonymous. We are concluded that a new chromosomal region with effects on the response to Marek's disease in chickens was characterized in this study. Within this region, the SNPs in the gallinacin candidate genes could potentially be used in a marker assisted selection program to enhance the response to Marek's disease. Analysis of the gallinacin genes in the protective pathways of disease resistance has also opened the possibilities for therapeutic strategies using endogenous antimicrobial peptides.

Genetic Distance Between Divergent White Leghorn Chicken Lines After Three Generations of Selection for Humoral Response to Sheep Erythrocytes

Gupta, T., Kumar, S., Prasad, Y. and Kataria, M.C. 2010. Genetic distance between divergent white Leghorn chicken lines after three generations of selection for humoral response to sheep erythrocytes. J. Appl. Anim. Res., 38: 265–269. Divergent selection based on humoral immune response to sheep erythrocytes was practised in IWG line of white Leghorn chicken for 3 generations. Genomic DNA was isolated from 35 birds of high immune response (HSRBC) and 35 from low immune response (LSRBC) lines and genetic distance between divergent lines was estimated by RAPD-PCR employing 23 random primers. Molecular sizes of the amplicons ranged from 255–2900 bp. Band sharing frequencies (BSF) ranged from 0.40 to 1.00 in HSRBC line and 0.45 to 0.94 in LSRBC line, whereas the between line BSF ranged from 0.52 to 0.90 with different primers. The genetic distance between the divergent lines (pooled over primers) was estimated as 0.07±0.00. Divergent selection for humoral immune response created genetic distance, although low. Study demonstrates effectiveness of the approach to develop suitable germplasm for identifying genetic mechanism behind high or low generalized humoral immune response of birds.

Assessment of Genetic Relatedness of Crossbred Chicken Populations Using Microsatellite Markers

To measure genetic relatedness between populations, for breeding purposes, we analyzed 170 birds from six crossbred populations of three pure lines of White Leghorn chickens, using 14 microsatellite markers. All the microsatellites were polymorphic, with 2-6 alleles. The mean number of alleles per locus was 3.21. The effective number of alleles varied from 1.14 to 3.94. The observed heterozygosity varied from 0.133 to 1.00, with a mean of 0.748. The F (IS) values were mostly negative, with an average of -0.345. The mean F (ST) value was 0.056. The Nm values ranged from 1.91 to 42.17. The highest genetic identity was observed between IWI x IWK and IWK x IWI. The relation between any two groups of crosses was more than 85%. The results suggest that the crossbred populations were very closely related.

Major Histocompatibility Complex and Background Genes in Chickens Influence Susceptibility to High Pathogenicity Avian Influenza Virus

The chicken's major histocompatibility complex (MHC) haplotype has profound influence on the resistance or susceptibility to certain pathogens. For example, the B21 MHC haplotype confers resistance to Marek's disease (MD). However, non-MHC genes are also important in disease resistance. For example, lines 6 and 7 both express the B2 MHC haplotype, but differ in non-MHC genes. Line 6, but not line 7, is highly resistant to tumors induced by the Marek's disease herpesviruses and avian leukosis retroviruses. Recently, survival in the field by Thai indigenous chickens to H5N1 high-pathogenicity avian influenza (HPAI) outbreaks was attributed to the B21 MHC haplotype, whereas the B13 MHC haplotype was associated with high mortality in the field. To determine the influence of the MHC haplotype on HPAI resistance, a series of MHC congenic white leghorn chicken lines (B2, B12, B13, B19, and B21) and lines with different background genes but with the same B2 MHC haplotype (Line 63 and 7(1)) were intranasally challenged with low dose (10 mean chicken lethal doses) of reverse-genetics-derived rg-A/chicken/Indonesia/7/2003 (H5N1) HPAI virus. None of the lines were completely resistant to lethal effects of the challenge, as evidenced by mortality rates ranging from 40% to 100%. The B21 line had mortality of 40% and 70%, and the B13 line had mortality of 60% and 100% in two separate trials. In addition, the mean death times varied greatly between groups, ranging from 3.7 to 6.9 days, suggesting differences in pathogenesis. The data show that the MHC has some influence on resistance to AI, but less than previously proposed, and non-MHC background genes may have a bigger influence on resistance than the MHC.

Circulating Corticosterone Reaction to Restraint and Adrenocorticotropin Hormone Administration in White Leghorns Selected for Immune Response Traits

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).

PCR-RFLP analysis of IL-2Rγ and IL-15Rα genes in Specialized Layer Chicken Lines

Singh, A.P., Kumar, S. and Gupta, T. 2008. PCR-RFLP analysis of IL-2Rγ and IL-15Rα genes in specialized layer chicken lines. J. Appl. Anim. Res., 33: 29–31. DNA polymorphism of IL-2Rγ and IL-15Rα was studied in 70 birds belonging to third generation of specialized White Leghorn chicken lines, divergently selected for humoral immune response to sheep erythrocytes by PCR-RFLP technique using specific primers. Amplification revealed product of 600bp for IL-2Rγ and 246bp for IL-15Rα genes. These amplicons digested with Hph I and Alu I revealed similar and monomorphic patterns in specialized layer chicken lines. It may be inferred that although specific primers amplified the target gene sequence but the PCR-RFLP pattern varied under different genetic backgrounds.