Project description:Background: Avian infectious bronchitis (IB) is an acute and highly contagious disease of the upper-respiratory tract caused by infectious bronchitis virus (IBV). Understanding the molecular mechanisms involved in the interaction between innate and adaptive immune responses to IBV infection is a crucial element for further improvements in strategies to control IB. To this end, two chicken lines, selected for high and low serum concentration of mannose-binding lectin (MBL), a soluble pattern recognition receptor, were studied. In total, 32 birds from each line (designated L10H for high and L10L for low MBL serum concentration, respectively) were used. Sixteen birds from each line were infected with IBV at 3 weeks of age and sixteen birds were left uninfected. Eight uninfected and eight infected birds from each line were euthanized at 1 and 3 weeks post infection. RNA sequencing was performed on spleen samples from all 64 birds used in the experiment. Differential gene expression analysis was performed for four comparisons: L10L line versus L10H line for uninfected birds at weeks 1 and 3, respectively, and L10L line versus L10H line for infected birds at weeks 1 and 3, respectively. Functional analysis based on the differentially expressed genes was performed using Gene Ontology (GO) Immune System Process terms specific for Gallus gallus. Results: Comparing uninfected L10H and L10L birds, we identified 1698 and 1424 differentially expressed (DE) genes at weeks 1 and 3, respectively. For the IBV-infected birds, 1934 and 866 DE genes were identified between the two lines at weeks 1 and 3, respectively. In both cases DE genes had FDR-adjusted p-value <0.05. The two most enriched GO terms emerging from the comparison of uninfected birds between the two lines were “Lymphocyte activation involved in immune response” (GO:0002285) and “Somatic recombination of immunoglobulin genes involved in immune response” (GO:0002204) at weeks 1 and 3, respectively. When comparing IBV-infected birds between the two lines, the most enriched GO terms were “Alpha-beta T cell activation” (GO:0046631) and “Positive regulation of leukocyte activation” (GO:0002696) at weeks 1 and 3, respectively. Conclusion: Healthy birds from the two lines showed significant differences in expression profiles for subsets of both adaptive and innate immunity-related genes, whereas comparison of the IBV-infected birds from the two lines showed differences in expression of immunity-related genes involved in T cell activation and proliferation. The observed transcriptome differences between the two lines indicate that selection for MBL had a much wider effect than solely on serum MBL concentration, and in addition influenced the innate and adaptive immune responses. Future research will focus on identifying signatures of selection in order to further understand molecular pathways be responsible for differences between the two lines as well as for efficient IBV immune protection.
2016-01-25 | GSE73423 | GEO
Project description:Selection at immunity genes in insular birds populations
Project description:Even though feather pecking (FP) in laying hens has been extensively studied, a good solution to prevent chickens from this behavior under commercial circumstances has not been found. Selection against FP behavior is possible, but for a more effective selection across different populations, it is necessary to characterize the genetic mechanism associated with this behavior. In this study, we use a high FP selection line, which has been selected for 8 generations. We present evidence of the presence of a major dominant allele affecting the FP behavior by using an argument based on the presence of mixture in the distribution of the observed FP and by studying the evolution of the proportion of very high FP along the sequence of 8 generations. This hypothesis is further supported by the fact that the gene transcription profile of the birds performing high FP differs from the profile of the other birds performing FP (456 genes differentially expressed from a total of 14,077 investigated genes). Keywords: severe feather pecking , selection , modeling , inheritance pattern
Project description:Even though feather pecking (FP) in laying hens has been extensively studied, a good solution to prevent chickens from this behavior under commercial circumstances has not been found. Selection against FP behavior is possible, but for a more effective selection across different populations, it is necessary to characterize the genetic mechanism associated with this behavior. In this study, we use a high FP selection line, which has been selected for 8 generations. We present evidence of the presence of a major dominant allele affecting the FP behavior by using an argument based on the presence of mixture in the distribution of the observed FP and by studying the evolution of the proportion of very high FP along the sequence of 8 generations. This hypothesis is further supported by the fact that the gene transcription profile of the birds performing high FP differs from the profile of the other birds performing FP (456 genes differentially expressed from a total of 14,077 investigated genes). Keywords: severe feather pecking , selection , modeling , inheritance pattern From each selection line (high feather pecking line, low feather pecking line and control line) 60 animals were randomly selected. Within each line the birds were randomly assigned to a cage of 20. The cages were kept in a randomized block design. Number of samples analyzed in total: 179 (60 high feather pecking line, 60 low feather pecking line, 59 control line samples. Common reference design using total-RNA purified from brain from a single F1 cross between the high and low feather pecking line as reference.
Project description:Purpose: This study is to more comprehensively understand the genome-wide host response to avian pathogen E. coli (APEC). Methods: Four-week-old male broiler chickens were infected with APEC O1 or given saline as a control. Bursas were collected at 1 and 5 days post-infection (dpi). Infected birds were classified based upon lesions in liver, pericardium and air sacs as having mild or severe pathology, representing resistant and susceptible phenotypes, respectively. Twenty-two individual bursa RNA libraries were sequenced, each yielding an average of 27 million single-end, 100-bp reads. Results: There were 2469 novel genes in a total of 16,603 detected. Large numbers of significantly differentially expressed (DE) genes were enriched in susceptible versus resistant birds and in susceptible versus non-infected birds at 5 dpi, as well as in 5 dpi versus 1 dpi susceptible birds. The DE genes represented signal transduction, immune response, and cell growth and death pathways. Conclusions: These data provide considerable insight into potential mechanisms of resistance to ExPEC infection, thus paving the way to develop strategies for ExPEC prevention and treatment, as well as enhancing innate resistance by genetic selection in animals.
Project description:Innate immunity is expected to play a primary role in conferring resistance to novel infectious diseases, but few studies have attempted to examine its role in the evolution of resistance to emerging pathogens in wild vertebrate populations. Here we used experimental infections and cDNA microarrays to examine whether changes in the innate and/or acquired immune responses likely accompanied the emergence of resistance in house finches (Carpodacus mexicanus) in the eastern United States subject to a recent outbreak of conjunctivitis-causing bacterium (Mycoplasma gallisepticum- MG). Three days following experimental infection with MG, we observed differences in the splenic transcriptional responses between House Finches from eastern U.S. populations, with a 12-year history of MG exposure, versus western U.S. populations, with no history of exposure to MG. In particular, western birds down-regulated gene expression, while eastern finches showed no expression change relative to controls. Studies involving poultry have shown that MG can manipulate host immunity, and our observations suggest that pathogen manipulation occurred only in finches from the western populations, outside the range of MG. Fourteen days after infection, eastern finches, but not western finches, up-regulated genes associated with acquired immunity (cell-mediated immunity) relative to controls. These observations suggest population differences in the temporal course of the response to infection with MG, and imply that innate immune processes were targets of selection in response to MG in the eastern U.S. population. Birds were randomly selected to be kept either as controls or infected via ocular inoculation with 20 μl of culture containing 1 x 104 to 1 x 106 color changing units/ml of an early 2007 Auburn MG isolate. All infected birds were inoculated with precisely the same volume of the same culture. Control birds were sham infected using sterile SP4 medium (Whitcomb 1983). Infected birds were euthanized three days (N=6 from Arizona and N=11 from Alabama) and 14 days (N=11 from Arizona and N=12 from Alabama) after treatment. Control birds were euthanized 14 days after sham-inoculation; Control (N=11 birds from Arizona and 9 from Alabama) and infected birds were maintained under identical conditions, but in separate rooms of an aviary. Infected birds were euthanized three days (N=6 from Arizona and N=11 from Alabama) and 14 days (N=11 from Arizona and N=12 from Alabama) after treatment. Control birds were euthanized 14 days after sham-inoculation. We used a common reference design (Yang & Speed 2002), in which we pooled 2 to 6 spleens from birds from the same population in the same treatment to generate enough mRNA for microarray hybridizations and hybridized two pools for each treatment from each population.
Project description:Gene duplication, accompanied by modification of the expression and/or function of one of the duplicates under the action of positive selection, followed by further duplication to produce multigene families of toxins is a well-documented process in venomous animals. This evolutionary model has been less described in parasitoid wasps, which use maternal fluids, including venom, to protect their eggs from encapsulation by the host immune system. The leptopilina venom proteomic data were used to evidence that specific RhoGAPs formed a family of protein that are associated with vesicles that act as transport systems to deliver them in the immune cells of their drosophila larval host. We showed that the gene encoding the cellular RacGAP1 is at the origin of the virulent RhoGAP family formed by successive duplications that evolved under positive selection. Almost all of these RhoGAPs lost their GAP activity and GTPase binding ability due to mutations in key amino acids suggesting new function(s) and mechanism of action in host cells that remain to be elucidated.
Project description:Purpose: This study would be useful to characterize the molecular mechanisms of an effective anti-bacterial response of chicken immune system. Methods: meat-type chickens were either infected with APEC O1 or given saline as a control. Thymii were collected on 1 and 5 days post-infection (dpi). The infected birds were classified based upon necropsy findings as having mild or severe pathology, representing resistant and susceptible phenotypes, respectively. Data from RNA sequencing experiments were analyzed using the R package, edgR, to identify the significantly differentially expressed (DE) genes. GO and pathway analysis using the R package GOseq identified many immune-related pathways. Results: Thousands of genes were DE at 5 dpi in susceptible vs. non-infected birds and in susceptible vs. resistant birds, as well as in susceptible birds at 1 vs. 5 dpi. In the contrast of susceptible birds with resistant or non-challenged birds, many immune response and signal transduction pathways were strongly induced, whereas the TCR signaling pathway was deeply suppressed to affect T cell development, differentiation, proliferation, and maturation. The transcriptomes of resistant and non-challenged birds were similar. Conclusions: These results provide the first comprehensive assessment of global gene networks and biological functionalities of DE genes in thymus in response to APEC infection, thus providing novel insights into key molecular genetic mechanisms that differentiate host resistance from susceptibility in this primary lymphoid tissue. These findings are foundational to the development of strategies to enhance host resistance to APEC infection.